CHAPTER 1 - INTRODUCTION TO COGNITIVE PSYCHOLOGY



CHAPTER 1 - INTRODUCTION TO COGNITIVE PSYCHOLOGY

COGNITIVE PSYCHOLOGY DEFINED

• Cognitive psychology - A study of how people perceive, learn, remember and think about information

• Dialectic - A developmental process where ideas evolve over time through a pattern of transformation:

~ A thesis is proposed - Thesis = statement of belief

~ An antithesis emerges

~ A synthesis integrates the two viewpoints

• A synthesis that advances our understanding - Serves as a new thesis

• Culture - Influences many cognitive processes, including intelligence

Assumptions in Cognitive Psychology

• The mind is an information processing system. (A computer metaphor is used to describe its operation)

Both ~ Process, store and retrieve symbols

~ Have large, but not unlimited memory capacity

~ “machines” operating on information

~ 2 levels, “software & hardware”

• Internal mental activities exist and can be studied systematically using a scientific approach without having to rely on overtly subjective and introspective methods

(→ A methodological assumption that implies the mind can be studied scientifically)

PHILOSOPHICAL ANTECEDENTS OF PSYCHOLOGY: RATIONALISM VS EMPIRICISM

• Earliest roots of psychology - 2 Approaches to understanding the human mind:

→ Philosophy & physiology

• Rationalism - Plato

~ Route to knowledge is through thinking & logical analysis

- True nature of reality doesn’t lie in observable phenomena, but in abstract forms underlying the phenomena

- No need for experiments

- NB in theory development

- Rene Descartes

~ Cogito ergo sum (I think, therefore I am)

~ Can’t rely on one’s senses because they can be deceptive

• Empiricism - Aristotle

- We acquire knowledge through empirical evidence (experience & observation)

- John Locke : Tabula Rasa

~ Born without knowledge, humans must seek it through observation

• Immanuel Kant - Synthesised the views of Descartes and Locke

PSYCHOLOGICAL ANTECEDENTS OF COGNITIVE PSYCHOLOGY

Early dialectics in the psychology of cognition

Structuralism: Understanding the structure of the mind

• Wilhelm Wundt

• Understand the structure of the mind by analysing the perceptions into constituent components

(affection/attention/memory/sensation)

• Deconstruct the mind into elementary components & see how they work together to create the mind

Introspection

* A method of structuralist research

* Deliberate looking inward at pieces of information passing through the mind

Functionalism: Understanding the process of the mind

• Focussing on the processes of thought, rather than its contents

• Seeks to understand what people do & why they do it

• Key to understanding lies in how the mind works, rather than its structural contents and elements

• used whichever means worked best, leads to:

Pragmatism

* Knowledge is validated by its usefulness

* William James - Leader in guiding Functionalism to Pragmatism

* John Dewey - Pragmatic approach to thinking and schooling

Associationism: An integrative synthesis

• Examines how elements in the mind become associated to result in a kind of learning

• Associations may result from:

Contiguity - Associating things occurring at the same time

Similarity - Associating things with similar features/properties

Contrasts - Associating polarities

• Ebbinghaus - Applied associanist principles systematically

- Random word lists (zax, mer, daf etc) noting how long it took him to memorise words

- Found rehearsal aids memory & fixes associations more firmly

• Thorndike - “satisfaction” key to forming associations

- “Law of effect” = A stimulus will produce a certain response over time

if an organism is rewarded for that response

• Predecessors of behaviourism.

Behaviourism

• Focuses only on relation between observable behaviour and environmental stimulii

• Tries to make physical what others call “mental”

• An extreme version of associationism

• Pavlov - Studied involuntary learning

- Involuntary learning linked the technician who fed the dogs with food in the dog’s minds

- Classical conditioning ~ Requires contingency (the effect is contingent on the presentation of the stimulus)

Proponents of Behaviourism

• John Watson - “Father” if radical behaviourism

- Psychologists should only focus on observable behaviour

- Thinking = Nothing more than subvocalized speech

• B.F. Skinner - All behaviour can be explained as reaction to the environment

- Rejected mental mechanisms

- Operant conditioning:

~ Strengthening/weakening of behaviour depending on presence/absence of reinforcement/punishment

Criticisms of Behaviourism

• Behaviourism couldn’t account for complex mental activities (eg language learning & problem solving)

• Psychologists wanted to understand not only behaviour, but what went on in the head

• Often easier to use behaviourist techniques to study animals than humans

Behaviourists daring to peek into the black box

• Mind = A black box best understood in terms of input & output

(Internal processes cannot be described because they are not observable)

• Tolman - Critic of radical behaviourism

- Understanding behaviour requires taking account of purpose and plan for the behaviour

- All behaviour is directed towards a goal

- Forefather to modern cognitive psychology

• Bandura - Learning can be social, resulting from observing the rewards/punishments given to others

- Social learning = learning through observation

Gestalt Psychology: The whole is more than the sum of it’s parts

• We best understand psychological phenomena if we view them as organised, structured wholes

- We cannot understand phenomena by breaking it down into smaller parts

• Highly critical of behaviourism

• Eg, to understand problem solving - Study insight rather than subvocal processing

EMERGENCE OF COGNITIVE PSYCHOLOGY

• Cognitivism - Belief that much of human behaviour can be understood in terms of how people think

- Rejects notion that mental processes shouldn’t be studied because they are unobservable/

Early role of psychobiology

• Lashley - Challenged Behaviourist view that brain is a passive organ, only responding to environmental contingencies

- Considered the brain an active organiser of behaviour

- Sought to understand how macro-organisation of the brain made possible complex, planned activities

• Hebb - Cell assemblies as basis for learning in the brain

- Cell assemblies = coordinated neural structures that develop through frequent stimulation

~ Develop over time as ability of one neuron to fire the next increases

• Noam Chomsky - Attacked Skinner’s proposition that language can be acquired through environmental contingencies

- Stressed biological basis & creative potential of language

- Defied behaviourist idea that we can learn language through reinforcement

as we can produce an infinite variety of sentences with ease

Add a dash of technology: Engineering, Computation and Applied cognitive psychology

• Artificial Intelligence (AI) - Attempts to construct systems that show intelligent information processing

• George Miller - Discovered people can remember about 7 pieces of information

- “Channel capacity” = hoe many items of a specific type an individual can remember

• Jerry Fordor - Modularity of mind

→ Mind has distinct modules/special purpose systems to deal with certain kinds of information

- Implies that processes used in one domain operate independently of those in other domains

- Modular approaches are useful in studying some phenomena (eg language learning)

less useful in studying intelligence, which draws on many areas of the brain

• Gall - Phrenologist (bumps on the head) Also had the idea of the mind as modular

COGNITION AND INTELLIGENCE

What is intelligence?

• Intelligence involves:

~ The capacity to learn from experience

~ The ability to adapt to the surrounding environment

• Metacognition - Understanding and control of one’s own thinking processes

• NB - Cultural differences in definition of intelligence

Three cognitive models of intelligence

Carrol: Three-Stratum model of intelligence

• Intelligence = A hierarchy of cognitive abilities comprising three strata

Stratum 1 → Many narrow, specific abilities (Spelling ability, speed of reasoning)

Stratum 2 → Various broad abilities ( Fluid intelligence, crystallized intelligence, short term memory etc)

Stratum 3 → A single general intelligence (g)

• Fluid ability = Speed & accuracy of abstract reasoning, esp for novel problems

• Crystallized ability = Accumulated knowledge and vocabulary

• This is the most widely accepted of the measurement-based models of intelligence

Gardner: Theory of multiple intelligences

• Intelligence - Multiple independent constructs, not just a single, unitary construct

• 8 Distinct intelligences, relatively independent

Linguistic Body-kinesthetic

Logical-mathematical Interpersonal

Spatial Intrapersonal

Musical Naturalist

• Modular view of the mind - Intelligences emanate from distinct portions of the brain

Sternberg: The Triarchic theory of intelligence

• Emphasises extent to which various aspects of intelligence work together

• Three aspects of intelligence:

1. Creative abilities - used to generate novel ideas

2. Analytical abilities - Ascertain whether ideas are good ones

3. Practical abilities - Used to implement ideas & persuade others of their value

• Cognition - At the centre of intelligence

• Components - Metacomponents ~ Higher order executive processes

~ Used to plan, monitor & evaluate problem solving

- Performance components ~ Lower order processes for implementing commands of metacomponents

- Knowledge-acquisition components ~ Processes used for learning how to solve the problem

RESEARCH METHODS USED IN COGNITIVE PSYCHOLOGY

Distinctive research methods

Experiments on human behaviour

• Controlled experiments - Usually in a laboratory setting

• Independent variable - The aspects that are manipulated

• Dependent variable - This varies depending on the independent variable

- The outcomes

• Control variables - Irrelevant variables that are held constant

• Confounding variables - An irrelevant variable that has been left uncontrolled

• Representative samples & random assignment

• Subtraction method - Estimating the time a cognitive process takes by subtracting

the amount of time it takes without the process, from the amount it takes with the process

Psychobiological research

• Studying the relationship between cognitive performance and cerebral events and structures

• Techniques fall in 3 categories:

1. Postmortem studying of the brain

2. Studying images of an individual known to have a particular defect

3. Obtaining info about cerebral processes during the normal performance of a cognitive activity

• In vivo studies - While the subject is still alive

Self-reports, case-studies and Naturalistic observation

• To obtain richly textured information about how individuals think in a broad range od contexts:

1. Self-reports (Own account of cognitive processes)

2. Case studies (In-depth studies of individuals)

3. Naturalistic observation

• Useful for formulation of hypotheses

• Generate descriptions of rare events we have no other way to measure

• Verbal protocol - Voicing all thoughts aloud during a cognitive process

• Case studies & naturalistic observations - High degree of ecological validity

Computer simulations and AI

• Computer simulations - researchers program computers to imitate a human function or process

Putting it all together

• Cognitive science - A cross-disciplinary field that uses ideas & methods from cognitive psychology, psychobiology,

AI, philosophy, linguistics & anthropology

- Use these ideas and methods to understand how humans acquire & use knowledge

5 “Key ideas” in cognitive psychology

1. Empirical data and theories are both important - Data can only be understood in the context of theory,

and theory is empty without data.

2. Cognition is generally adaptive, but not always - Heuristics that make us more efficient also lead to mistakes

3. Cognitive processes interact with each other and with noncognitive processes

4. Cognition needs to be studied through a variety of scientific methods

5. All basic research in cognitive psychology may lead to applications,

& all applied research may lead to basic understandings

7 Underlying issues that play a role in cognitive psychology

1. Nature vs nurture

2. Rationalism vs empiricism

3. Structure vs process

4. Domain generality vs domain specificity

5. Validity of causal inferences vs ecological validity

6. Applied vs basic research

7. Biological vs behavioural methods

CHAPTER 2 - PERCEPTION

FROM SENSATION TO REPRESENTATION

• Perception - Not just seeing what is projected onto the retina

- Processing stimuli, giving it meaning and interpreting it

Some basic concepts of perception

• James Gibson - Provided a useful framework for studying perception:

* Distal Object - (far) The object in the external world

* Informational medium - The medium in which a pattern is created by the distal object,

eg sound waves, reflected light, chemical molecules, tactile information

* Proximal stimulation - (near) The physical stimulation by the informational medium

* Perceptual object - What you see/hear/smell etc

→ Perception - when a perceptual object is created in the perceiver that reflects the properties of the external world

• The process is part of a continuum

- No clear line between perception & cognition/sensation & perception

- Different processes answer different questions

• Fundamental question - “How do we achieve perceptual stability in the face of utter instability

at the level of sensory receptors?”

• Sensory adaptation - Receptor cells react to constant stimulation by ceasing to fire until there is a change in stimulus

- We stop detecting the presence of the stimulus

- Stabilized images ~ Follow eye movements & do not move across the retina

~ Seem to disappear

- Ensures that sensory information is changing constantly (eye makes small movements)

• Ganzfeld - An unstructured visual field

- The eye stops perceiving it after a few minutes because they adapt to the stimulus

THUS - Stimulus variation - An essential attribute of perception

Seeing things that aren’t there, or are they?

• Mental precept - A mental representation of the stimulus that is perceived

- Without this the perceptions cannot be meaningfully grasped

• Perceptual illusions - Seeing what isn’t there, or not seeing what is

- Suggests that what we sense is not necessarily what we perceive.

→ Our minds manipulate sensory information to create mental representations

How does our visual system work?

• Light - Precondition for vision

- Electromagnetic radiation that can be described in terms of wavelength

- Visible wavelengths ~ Only a small range (380 - 750 nanometres)

- Follows the following pathway:

* Cornea - Protective covering of the eye, a clear dome

* Pupil - Opening in the centre of the iris

* Crystalline lens

* Vitreous humor - Gel-like substance that comprises most of the ye

* Retina - Where electromagnetic light energy is transduced into electrochemical impulses

- About as thin as a page, but has 3 layers of neuronal tissue:

1. Ganglion cells - Their axons constitute the optic nerve

2. Three types of interneuron cells make up this middle layer;

♦ Amacrine cells & horizontal cells - Make single lateral/horizontal connections among adjacent areas

of the retina in the middle layer

♦ Bipolar cells - Make dual connections forward & outward to the ganglion cells

- And backward & inward connections to third layer of retinal cells

3. Photoreceptors - Comprise the 3rd layer of the retina, converting light energy into electrochemical energy

- 2 Kinds: Rods and cones

- Photopigments - Chemical substances in the rods & cones that react to light

~ Rods - About 120 million, Long & thin, More highly concentrated in the periphery of retina

- Responsible for night vision & sensitive to light & dark stimuli

~ Cones - About 8 million, short & thick, More highly concentrated in the foveal region than the periphery

• Fovea - Small, thin region of retina, the size of a head of a pin

- Vision is most acute here

• Optic nerve - Formed by the axons of the ganglion cells

• Optic chiasma - Where the optic nerves of the eyes meet at the base of the brain

- Ganglion cells from the inner/nasal part of retina cross over here to extend to the opposite brain hemisphere

(Ganglion cells from temporal area go to same side hemisphere)

• After optic chiasma - 90% of ganglion cells go to Thalamus (lateral geniculate nucleus)

→ From there information goes to primary visual cortex (in occipital lobe)

• So neurochemical impulses follow the path:

Bipolar cells → Ganglion cells → thalamus → visual cortex

• Lens of eye inverts the image - Brain receives an upside-down image

Pathways to perceive the what and the where

• Visual pathway - Path of visual information, from entering perceptual system to being fully processed

- 2 -Neural pathways process different aspects of the same stimuli

- Information from primary visual cortex in occipital lobe is forwarded through 2 fasciculi (fibre bundles)

- Both arise from same early visual areas

The what/where Hypothesis:

• Best supported by research on monkeys -Parietal lobe lesions - Know what something is, but not where

- Temporal lobe lesions - Know where something is, but not what it is

Dorsal Pathway Ventral Pathway

* Ascends towards the parietal lobe * Descends towards the temporal lobe

* Where pathway - Processes location & motion info * What pathway - Processes colour, shape and identity

The what/how hypothesis:

• Pathways refer to what things are & how they function

• Spatial information re location is always present in visual information processing

• Best supported by evidence of processing deficits - Some deficits impair ability to identify objects, others impair ability to

reach for objects.

Dorsal Pathway Ventral pathway

* How pathway * What Pathway

* Controls movement in relation to objects * Responsible for identification of objects

APPROACHES TO PERCEPTION: HOW DO WE MAKE SENSE OF WHAT WE SEE?

•Bottom-up Theories - Perception starts with stimuli

- Data-driven/stimulus-driven theories

Main theories: Direct perception: Gibson’s Theory, Template theories, Top-Down, Bottom-Up Theories.

Recognition-by-components theory

• Top-down theories - Perception is driven by high-level cognitive processes, existing knowledge & prior expectations

then works their way down to considering sensory data

- Expectations are important

Main - Constructive perception theory

• Both types of theories deal with different aspects of the same phenomenon

→ A complete theory of perception will encompass both approaches

Bottom-up theories: Direct perception

• Gibson - Questioned associationism

- Gibson’s Theory of Direct Perception

• Information in our sensory receptors (Including sensory context) = All we need to perceive anything

• Also called ecological perception - Environment supplies us with all we need for perception

- Refers also to Gibson’s concern with perception in the everyday world, not in a lab

• No need for higher cognitive processes to mediate between sensory experiences & perceptions

• Real world - Contains sufficient contextual information for perceptual judgements

• This contextual info is used directly - We are biologically tuned to respond to it

• Texture gradients - Cues for depth and distance

• Contextual information - Might not be readily controlled in a laboratory setting , but is likely available in real world

• Ecological restraints also apply to internal representations formed from perceptions

• Elanor Gibson - research in infant perception

- Infants, who lack prior knowledge and experience, develop many aspects of perceptual awareness

• Direct perception - Play a role in recognising emotion in faces (we don’t expect the emotion and then see it in the face)

Neuroscience and Direct Perception

• Neuroscience indicate direct perception is involved in person perception

• 20 - 100milliseconds after a visual stimulus, mirror neurons start firing

• Mirror neurons - Active when acting, or when seeing someone else acting

• We may understand expressions, emotions and movements of someone we observe before we even have time to

think about it.

• Separate neural pathways - (what pathways) For form, colour & texture

Template theories

• Templates = Detailed models for patterns we may potentially recognise

- We recognise a pattern by comparing it with our templates

& choosing the template that matches what we observe

• Template matching used in - Fingerprinting, barcode scanning, chess masters having templates of game strategies

• Chunk-based theories - Expertise is attained by acquiring chunks of knowledge in the long-term memory

that can later be assessed for fast recognition

• In other instances of template-matching - Only an exact match will do

In perception - It is impossible to have an exact template of all possible instances of an object

• Template theories - Fail to explain certain instances of the perception of letters

Neuroscience and template theories

• There seems to be a difference between perception of letters & of digits

• Area near left fusiform gyrus - Activates more when presented with letters than with digits

(May play minor role in processing digits)

Feature-matching theories

• Alternative explanation of pattern and form perception

• We attempt to match features of a pattern to features stored in memory - not the whole pattern to a template

Pandemonium model: (see p60 for examples)

• Oliver Selfridge

• Metaphorical “demons” with specific duties receive and analyse the features of a stimulus

• Image demons - Receive retinal image and pass it on to feature demons

Feature demons - Each demon calls out if there is a match between the stimulus & the given feature

Cognitive demons - Shout out patterns stored in memory that conform to the features noticed by feature demons

Decision demon - Listens to the pandemonium and decides what has been seen, based on which cognitive demon shouts most

frequently (ie has the most matching features)

• Other feature models have been proposed - Most distinguish between different kinds of features

• Global precedence effect - When local features are close together

- Local features take longer to identify if they differ from the global feature

- The global feature is identified just as quickly regardless of what the local features are

• Local precedence effect - When local features are spaced far apart

- Global feature take longer to identify if it differs from the local features

- the local features are identified at the same rate, regardless of the global feature

Neuroscience and Feature-Matching theories

• Researchers use single-cell recording techniques with animals

• Measure responses of individual neurons to visual stimuli in the visual cortex

• Then mapped those neurons to corresponding stimuli for particular locations in the visual field

→ Shows the visual cortex contain neurons that respond to only a particular kind of stimulus (eg a horizontal line)

& only if that stimulus falls onto a specific region of the retina

THUS - each cortical neuron can be mapped to a specific receptive field on the retina

Disproportionately large amount of the visual cortex is devoted to neurons mapped to the receptive fields in the

foveal region of the retina - the area of most acute vision.

• Most cells in the cortex:

- Don’t respond simply to spots of light

- Respond to “specifically oriented line segments”

- Show a hierarchical structure in the degree of complexity of the stimuli to which they respond

(in line with ideas behind Pandemonium model)

→ Outputs of cells are combined - Create higher-order detectors that can detect increasingly complex features

Lowest level - Cells respond to lines

Higher level - Respond to corners and edges, then shapes, etc

• Gnostic units - Neurons that can recognise a complex object : “grandmother cells”

• As the stimulus proceeds through the visual system to higher levels of the cortex:

~ Size of the receptor field increases

~ Complexity of the stimulus required to prompt a response also increases

• Hubel & Wiesel - Believed there are 2 kinds of visual cortex neurons, simple cells & complex cells

- Differ in complexity of the information about stimuli they processed

- Proved to be over simplified

* Cells can serve multiple functions

* Cells operate partially in parallel:

- Spatial information about location is processed simultaneously with info about the contours of the object

- Complex judgements re what is perceived are made early in information processing

• Other investigators found - Feature detectors that respond to corners, angles, stars, triangles

• In some areas of the cortex - Sophisticated complex cells fire only in response to very specific shapes , regardless of the size of the stimulus

-As the stimulus decreasingly resembles the optimal shape,the cells are decreasingly likely to fire.

Recognition-by-components theories

• Explains our ability to perceive 3D objects with the help of simple geometric shapes

• Geons - Simple geometric 3D shapes (Geometrical ions)

- eg bricks, cylinders, wedges, cones & their curved axis counterparts

• Irving Biederman - Recognition by components (RBC) theory

• We recognise objects by - Observing the edges & decomposing them into geons

• Geons - Can also be recomposed into alternative arrangements

- Simple & viewpoint-invariant

• Cells in inferior temporal complex - React more strongly to changes in geons than to changes in other geometrical

properties (eg change in size or diameter of a cylinder)

• Explains how we may recognise general instances of objects

• Cannot explain how we distinguish one object from another similar one (one face from another)

• Aspects of the theory that need further work:

- How the relations between parts of an object can be described

- How to account for the effect of prior expectation & environmental context

(this last is an issue with all bottom-up theories)

Neuroscience and recognition-by-Components theory

• To confirm the theory - Neurons react to properties of an object that stay the same, regardless of the angle of view

→ Some neurons are sensitive to only viewpoint-invariant properties

BUT - Many are not

THUS - it is currently unclear whether this theory is correct

(see top down theory on next page)

How do bottom-up and top-down theories go together?

• Theories seem to contradict each other

• Constructivists - Prior knowledge NB

- Information in sensory receptors is simple and ambiguous

Direct-perception - Completeness of info in receptors

- Little need for complex information processing

• Perceptual processes - More complex, esp when sensory stimuli appear only briefly or is degraded.

• We use a combination of sensory info & past knowledge for perception

• 1st stage of visual pathway - Only that which is in the retinal image of an object

→ Soon colour, orientation motion, depth, spatial frequency & temporal frequency is represented

→ Later-stage representations emphasize viewer’s interest/ attention - dependent on attentional focus

• Vision for different things take different forms:

- Visual control of actions ~ Mediated by cortical pathways different from those for visual control of perception

- When we just look at an object, we process the info differently than when we intend to pick up the object

• In general we perceive objects holistically, but if we plan to act on them we perceive them more analytically

Current theories - explain some, but not all the phenomena we encounter in the study of form and pattern perception

Comprehensive theory - Still forthcoming, would need to account for all context effects eg configural-superiority effect

Top-down theories

Constructive perception

• Perceiver constructs a cognitive understanding (perception) of a stimulus

• Concepts and cognitive processes influence what is perceived

• Sensory information - Used as the foundation for the structure, but other sources of information is also used to build the perception

• Also called intelligent perception - Stresses role of higher-order thinking & learning in perception

• Perception is reciprocal with the world we experience:

- It both affects, and is affected by the world as we experience it

• Interesting feature of the theory - It links intelligence to fairly basic processes of perception

- Perception comprises a sophisticated set of processes that interact with & are guided by intelligence

- What you perceive is shaped by what you know & think

• Perceptual constancy - A car seems to stay the same size even if the image gets bigger as it approaches

• Colour constancy - Colours seem to stay the same even if lighting changes

→ Suggests high-level constructive processes are at work during perception

• During perception we form & test hypotheses regarding precepts:

~ What we sense (sensory data)

~ What we know (knowledge stored in memory)

~ What we can infer (using high-level cognitive processes)

• We usually make correct attributions regarding our visual sensations - Due to unconscious inference

→ Process by which we unconsciously assimilate information from a number of sources to create perception

• Successful constructive perception requires - Intelligence & thought in combining sensory information

with knowledge gained from experience

• Context effects = The influence of the surrounding environment on perception

- Not explained by bottom-up approaches

(experiment - Show people a context, eg a kitchen, then a list of objects

Objects appropriate to the context are recognised more rapidly)

• Configural-superiority effect - A context effect where objects in a configuration are easier to perceive than in isolation

even if they are more complex in a configuration

• Object-superiority effect - A target line that forms part of a drawing of a 3D object is identified more accurately

than a target that forms part of a disconnected 2D pattern

→ Parallels findings in the study of letter & word recognition:

• Word-superiority effect - People recognise a letter more easily if it is part of a string that makes sense

• Intelligence is an integral part of perceptual processing

• Extreme top-down position

- Would underestimate the importance of sensory data

- Prone to inaccuracies (expecting a friend and seeing a stranger, we’d think the stranger was the friend)

- Would form hypotheses and expectations that inadequately evaluate sensory data

• Extreme bottom-up position

- Would not allow for any influence of past experience or knowledge

PERCEPTION OF OBJECTS AND FORMS

Viewer-centred vs Object-centred perception

• Viewer-centred representation - Individual stores the way an object looks to them

- What matters is the appearance of the object to the viewer

- Shape of the object changes depending on the angle

- A number of views are stored, and we have to rotate an object in our minds till it fits a stored image to

recognise it.

• Object-centred representation - Individual stores a representation of the object, independent of appearance

- Shape of the object stays stable across different orientations

- Stability is achieved by establishing major & minor axes for the object

→ these serve as basis for defining further properties

• Reconciliation of these 2 viewpoints:

- Recognition of objects occur on a continuum: viewpoint-centred to object-centred cognitive mechanisms

- Eg a pic of a car that’s inverted: Object-centred mechanisms recognise it as a car

Viewpoint-centred mechanisms recognise it as inverted

• Landmark - Centred representation - Info is characterised by its relation to a well-known/prominent item

• In the lab people switch between the three strategies

• There are differences in brain activation between the strategies

The perception of groups - Gestalt laws (see p72 for examples)

• Grouping similar things - Brings order and coherence to perception

- Reduces the number of things to be processed

- We can decide which things belong together/to the same group

→ We organise objects in a visual array into coherent groups

Gestalt approach to form perception:

• Useful to understand how we perceive groups of objects/parts of objects to form integral wholes

• Kurt Koffka, Wolfgang Kohler, Max Wertheimer. Germany, early 20th century

• Based on notion - The whole differs from the sum of its parts

• Law of Pragnanz - We tend to perceive any given visual array in a way that most simply organises the different

elements into a stable and coherent form

- So we don’t experience a jumble of unintelligible forms

• People use gestalt principles even when confronted with novel stimuli

• Gestalt principles of form perception - Simple, yet characterise much of our perceptual organisation

- Appear to apply only to humans and not to other primates.

* Figure - ground : Some objects/figures in a visual field seem prominent while other aspects recede into the background

* Proximity - When we see an assortment of objects, we tend to see those close together as forming a group

* Similarity - We tend to group objects on the basis of similarity

* Continuity - We tend to perceive smoothly flowing/continuous forms rather than disrupted/discontinuous ones

* Closure - We tend to perceptually complete objects that are not closed/complete

* Symmetry - We tend to perceive objects as forming mirror images around their centre

Recognising patterns & faces

Two different pattern recognition systems

• 2 Systems for recognising patterns: (Martha Farah)

• Feature analysis system - Recognising part of objects and assembling them into distinctive wholes

- Seeing someone vaguely familiar & analysing the features to recognise a friend from years ago

• Configurational system - Specialises in recognising larger configurations

- Not well equipped to analyse parts of objects or their construction

- Most relevant to the recognition of faces (might not even notice specific changes)

• Face recognition - In part in the fusiform gyrus of the temporal lobe

(responds intensely when we look at faces, but not when we look at other objects)

- Infants track pics of faces more rapidly than pics of other complex objects

→ is special, and different from recognition of other objects

* experiment - People were shown whole faces and parts of faces, whole houses and parts of houses

→ They recognised the parts of houses as fast as the whole houses

They took longer to recognise parts of faces than whole faces

This indicates that face recognition is esp dependent on the configurational system

~ Example of the configurational effect - If you stare at a distorted face, and then at a normal one,

the normal one seems distorted in the opposite direction.

• Cognitive processing of faces & emotion - Can interact

- Happy faces are rated as more familiar than neutral/negative ones

- The amygdala processes some negative emotions automatically

→ esp if you are not distracted or if you are an anxious person

• “Face positivity” effect - Older people show a preference for looking at happy faces & away from sad /angry ones

The neuroscience of recognising patterns and faces

• Emotion - Increases activation in the fusiform gyrus when processing faces

(People shown faces show increased activation if they have to identify the emotion of the face)

• Autistics - Impaired emotional recognition

- Less active fusiform gyrus than nonautistic population

• Contrasting view - Fusiform gyrus not specialized for face perception

- Areas of the brain are not all-or-none in what they perceive, but are differentially activated

in degrees, according to what is perceived

• Expert individuation hypothesis - Another theory for the role of the fusiform gyrus

- Fusiform gyrus is activated when one examines an item with which one has visual expertise

• Prosopagnosia - The inability to recognise faces (can still recognise emotion)

- Implies damage to the configurational system

- Esp influenced by lesions to the right fusiform gyrus

(esp bilateral lesions that include the right temporal lobe)

THE ENVIRONMENT HELPS YOU SEE

Perceptual constancies

• Perceptual constancy - When our perception of an object remains the same

even when our proximal sensation of the distal object changes.

- An approaching car doesn’t seem to get bigger, even though it does on the retina

- Perception remains constant although the proximal sensation changes

• Size constancy - Perception that size remains constant despite changes in n the size of the proximal stimulus

Muller-Lyer illusion - An example of size constancy

- 2 Line segments that are the same length appear to be of different lengths. (see p79)

• Shape constancy - Perception that an object maintains the same shape despite changes in the proximal stimulus

Depth perception

Depth cues

• Help us perceive 3D space even though proximal stimuli on the retina comprises only a 2D image

• Monocular depth cues

- Can be represented in 2 dimensions & perceived with just one eye

- Texture gradients, relative size, interposition, linear perspective, aerial perspective,

location in the picture plane, motion parallax (requires movement) (p83 for table)

• Binocular depth cues

- Based on sensory information in 3 dimensions, from both eyes

- Uses relative positioning of the eyes

- Binocular disparity : 2 eyes send increasingly disparate images to the brain as objects approach

Brain interprets the degree of disparity as an indication of distance

- Binocular convergence: 2 eyes increasingly turn inwards as objects approach

For objects viewed at relatively close locations

• Strabismic eyes - Not aligned properly. 8% of people can still have depth perception

- Sensitive area in retina other than fovea captures part of the space that should have been captured

- Usually goes along with partial inhibition of signals from the fovea

- IF the fovea stays sensitive, a double image results that can be fused to generate stereoscopic vision

• Depth perception - Can depend on more than just distance/depth at which an object is located:

* Perceived distance - Influenced by effort required to walk to the location of the target

* Target seems farther when wearing a heavy backpack

* THUS there can be an interaction between the perceptual result and the perceived effort required to reach the object

• Depth perception - A good example of how cues facilitate our perception.

The neuroscience of depth perception

• Binocular neurons - Specialize in the perception of depth

- Integrate information from both eyes to form information about depth

- In the visual cortex

• Visual shape processed - In ventral visual stream + other visual areas

such as lateral occipital cortex & ventral temporal cortex

• Initial processing of moving 3d shapes - Primary visual cortex

Then - Human motion complex (mHT), area concerned with motion processing

Then - Depth & shape information, mainly in V5 region of the visual cortex (also medial parietal cortex)

Then - Different features are analysed to infer shape (Lateral occipital cortex)

Inferred shape - Compared with shape representation in the ventral occipital & ventral temporal areas of the cortex

Lastly - Activation in parietal cortex & primary visual cortex

Suggests the parietal cortex is involved in top-down processes

that influence the areas in the primary visual cortex where visual stimuli are being processed in the beginning.

DEFICITS IN PERCEPTION

Agnosias and Ataxias

Agnosia - Difficulties in perceiving the “what”

• Trouble perceiving sensory information

•Often caused by damage to the border of the temporal & occipital lobes or restricted oxygen flow to the brain

•Many kinds of agnosias, not all of them visual

• Normal sensations, can perceive colours & shapes, but can’t recognise them for what they are

• Visual-object agnosia - Can see all parts of the visual field, but what they see makes no sense

• Simultagnosia - Unable to pay attention to more than one object at a time

- Disturbance in the temporal region of the cortex

• Prosopagnosia - A severely impaired ability to recognise human faces

- Functioning of the right-hemisphere fusiform gyrus implicated

- Associated with damage to the right temporal lobe

• Agnosia tends to persist over time

Optic Ataxia - Difficulties in knowing the “how”

•Impairment in the ability to use the visual system to guide movement

• Results from processing failure in the posterior parietal cortex, where sensorimotor information is processed

• Higher-order processes seem to be involved - Ataxic patients can grasp objects under certain circumstances:

~ If they wait a few seconds movement is improved

~ Immediate movements - Executed through dorsal-stream processing

Delayed movement - Ventral system (occipito-temporal & temporo-parietal areas)

Are perceptual processes independent of each other?

• Perceptual deficits - Very specific

• Modular processes - Specialized for particular tasks

- Can involve only visual processes or an integration of visual and auditory processes

• For a perceptual process (eg face recognition) to be considered modular

- Process should be domain-specific and information used must not flow freely across different modules

- Thus other perceptual processes should not contribute to, interfere with or share information with the modular

process

Anomalies in colour perception

• More common in men than women

• Genetically linked

• Can result from lesions to ventro-medial occipital & temporal lobes

• Achromancy - Rod monocromancy

- No colour vision at all, see only shades of gray

- Nonfunctional cones, all vision takes place through the rods

• Dichromancy - 2 mechanisms for colour perception works, and one is dysfunctional

- Result is one of three types of colour perception deficits

- red-green colour blindness the most common

- Protanopia ~ Extreme form of red-green colour blindness

- Deuteranopia - Trouble seeing greens

- Tritanopia - Blues and greens are confused,

and yellows can seem to disappear/appear as light shades of red

CHAPTER 3 - COGNITIVE NEUROSCIENCE

NEURONAL STRUCTURE AND FUNCTION

Receptors and Drugs:(see p114 for table of neurotransmitters)

• Neuron - Individual neural cell

- Transmits electrical signals

- Arranged in networks providing information & feedback to each other

- Vary in structure but almost all have same basic 4 parts (soma, dendrites, axon and terminal buttons)

• Neocortex - Has greatest concentration of neurons (100 000 per mm3)

- Part of brain associated with complex cognition

• Soma - Contains nucleus of the cell

- Connects the dendrites to the axon, integrates information

• Dendrites - Many branchlike structures that receive information from other cells

- Learning ~ associated with formation of new neuronal connections

~ Increased complexity in the branching structure of the dendrites in the brain

• Axon - Single long tube that extends from the soma

- Responds to information by transmitting an electrochemical signal which travels to the terminus from where it

can be transmitted to other neurons.

- Roughly equal amounts of myelinated & unmyelinated axons

• Myelin - White, fatty substance surrounding some axons

- Insulates & protects longer axons from electrical interference by other neurons in the area

- Speeds up the conduction of information (up to 100m/second)

• Nodes of Ranvier - Small gaps in myelin coating

- Increases conduction speed by helping create action potentials (electrical signals)

- Degeneration of myelin sheaths is associated with multiple sclerosis

• Terminal buttons - Small knobs at the end of branches of axons

- Don’t directly touch the dendrites of the next neuron

• Synapse - Small gap between terminal buttons and dendrites of next neuron (sometimes the soma)

- Serves as juncture

- NB in cognition, learning increases size and number of synapses in the brain

• Neurotransmitters - Released by terminal buttons

- Chemical messengers for transmission of information across the synaptic gap

• More than 100 transmitter substances have been identified, but there are likely still more

• Researchers wish to understand how neurotransmitters interact with drugs, moods, abilities & perceptions

• We know much abt the mechanics of impulse transmission,&little abt how the nervous system’s chemical activity relates

2psychological states

• 3 Types of chemical substances are involved in neurotransmission:

Monoamine neurotransmitters - Synthesized by the nervous system through enzymatic actions on one of the amino acids

on our diet

Amino-acid neurotransmitters - Obtained directly from amino acids in our diet, without further synthesis

Neuropeptides - Peptide chains, molecules made from the parts of two or more amino acids

• Some neurotransmitters:

* Acetylcholine - Monoamine neurotransmitter synthesised from choline

- Associated with memory functioning, loss associated with Alzheimer’s

- NB role in sleep and arousal

* Dopamine - Monoamine neurotransmitter synthesised from tyrosine

- Attention, learning & movement coordination

- Involved in motivational processes eg reward & reinforcement

- Schizophrenics show very high levels of dopamine

- Parkinson’s disease show low levels of dopamine

- People who receive dopamine sometimes show pathological gambling (impaired impulse control)

* Serotonin - Monoamine neurotransmitter synthesised from tryptophan

- NB role in eating behaviour & body-weight regulation

- Involved in aggression & regulation of impulsivity

VIEWING THE STRUCTURES AND FUNCTIONS OF THE BRAIN

Postmortem studies

• Researchers document behaviour of person with brain damage while they are alive, & dissect their brains after death

→ Assumes a connection between location of lesions & affected behaviour

• Can trace a link between a certain type of behaviour & anomalies in a particular location in the brain

• Examples - Brocca’s patient Tan: Severe speech impediments

→ lesions in Brocca’s area of the frontal lobe

- Alzheimer’s patients distinctive tangled fibres in the brain tissue.

Studying live nonhuman animals

• A way to study physiological processes and functions of the living brain.

• Single-cell recordings - A very thin electrode is inserted next to a single neuron in the brain of an animal

- Changes in electrical activity are recorded

- Can measure effects of stimuli on the activity of individual neurons

→ Neurons fire constantly, so task is to find stimuli that produce a consistent change in activity of the neuron

• Selective lesioning - Surgically removing/damaging parts of the brain & observing resulting functional deficits

- Recent years: Neurochemical ways to induce lesions

Some drugs destroy only cells that use a particular neurotransmitter,

sometimes only temporarily

• Genetic knockout procedures - Creating animals that lack certain kinds of cells/receptors in the brain

Studying live humans

Electrical recordings

• Electroencephalograms (EEG) - Recording of the electrical frequencies & intensities of the living brain

• Typically recorded over a long period

• Makes it possible to study brainwave activity indicative of changing mental states

• Information is not localised to specific cells

• Very sensitive to changes over time

• Used a s tool in diagnosis of epilepsy - Can show whether seizure originates in both sides of brain,

or one side & then spreads

• ERP = Event-related potential

- The record of a small change in the brain’s electrical activity in response to a stimulating event

- Fraction of a second

- Provide good info about the time-course of task-related brain activity

→ ERP’s cancel out the effects of noise by averaging out activity that is not task-related

- Can be used to examine developmental changes in cognitive abilities

Static imaging techniques

• Still images to reveal the structures of the brain

• X-ray based techniques - Angiogram & CT scan

- Observation of large abnormalities, but limited in resolution & can’t sho smaller lesions

• CT/CAT - Computed topography scan

- Several X-ray images of the brain, taken at differing angles, resulting in a 3d image

• Angiography - Looks at blood flow in the brain

- Dye in the artery makes the circulatory system show on an x-ray

- Can detect strokes, aneurysms or arteriosclerosis

• MRI - Magnetic resonance imaging scan

- High-resolution images of the structure of the living brain

- Analyses magnetic changes in the energy of the orbits of nuclear particles in the molecules of the body

- Much clearer picture than a CT scan

- Facilitates detection of lesions, but doesn’t show much about physiological processes

• Structural MRI - Provides images of brain’s size and shape

• Functional MRI - Visualise the parts of the brain that are activated when a person is engaged in a particular task

Metabolic Imaging

• Rely on changes in the brain as a result of increased consumption of glucose and oxygen in active areas of the brain

→ Active areas consume more glucose & oxygen than inactive areas

• Subtraction method - Subtracting the activity during a control task from the activity during the task of interest

→ Resulting difference is analysed statistically.

- Shows which areas are responsible for performance of particular tasks

NB - Reveals net brain activity for certain areas

Cannot show whether the effect is positive or negative

Assumes that activation is purely additive - Disregards interactions among elements

• PET scan - Positron emission tomography

- Measures increases in oxygen consumption

- Track use of oxygen by giving a mildly radioactive form of oxygen that emits positrons as it is metabolised

- Brain is scanned to detect positrons

- Computer analyses data to produce images of the physiological functioning

- Assists in diagnosis of disorders of cognitive decline by showing abnormalities in the brain

- Has shown that blood flow to occipital lobe increases during visual processing

- Used for comparison of high & low intelligence

- Not highly precise ~ Require min 30 seconds to produce data,

averaging what happens in the 30 seconds can lead to errors

• fMRI - Functional magnetic resonance imaging

- Uses magnetic fields to construct a detailed representation in 3d of levels of activity in parts of the brain

- Builds on MRI, but uses increases in oxygen consumption to construct images

- Same basic idea as PET scan but doesn’t require radioactive particles

- Magnetic field induces changes in the particles of oxygen atoms

- More active areas draw more oxygen, so just after activity a reduced amount of oxygen should be detectable

- Less invasive that PET

- Has higher temporal resolution: Measurements can be taken for activities lasting fractions of a second

- Drawback : Cost

• phMRI - Pharmacological MRI

- Combines fMRI methods with the study of psychopharmacological agents

- Examines role of psychopharmacological agents on the brain

- Examines role of agonists & antagonists on same receptor cells

- Allows for the examination of drugs used for treatment

• DTI - Diffusion tensor imaging

- Also related to fMRI

- Examines the restricted dispersion of water in tissue, esp in axons

- Water in the brain: Restricted in its movement by axons and their myelin sheaths

- Measures how far protons have moved in a direction in a specific time

- Useful in mapping white matter in the brain & examining neural circuits

• TMS - Transcranial magnetic stimulation

- Bypasses some of the problems with other techniques

- Temporarily disrupts the normal activity of the brain in a limited area

- Thus can imitate brain lesions & stimulate brain regions

- A coil on the head is magnetised by passing an electric current thought it,

this disrupts the functioning of a small area directly beneath it (abt 1 cubic cm)

- Restricted to brain regions close to the surface

- Advantage: Can examine causal relationships (other techniques are limited to correlational relationships)

• MEG - Magnetoencephalography

- Pics up magnetic fields emitted by changes in brain activity

- Allows localization of signals ~ One can know what different parts of the brain are doing at different times.

- One of the most precise of the measuring methods

- Used to help surgeons locate pathological structures in the brain

- Recent application: Relieving phantom limb pain

• Current techniques - Still don’t provide unambiguous mapping of functions to brain structures, regions or processes

- Can only infer suggestive indications of relationship

- These can be increasingly precise, but no cause-effect conclusions yet.

COGNITION IN THE BRAIN: THE ANATOMY AND MECHANISMS OF THE BRAIN

Gross anatomy of the brain: Forebrain, midbrain, hindbrain

The Forebrain

• Located toward the top & front of the brain

• Cerebral cortex + basal ganglia + limbic system + thalamus + hypothalamus

• Cerebral cortex - NB role in thinking & other mental processes

- Outer layer of the cerebral hemispheres

• Basal ganglia - Collections of neurons crucial to motor function

- Dysfunction results in motor deficiencies

→ tremors, involuntary movements, changes in posture & muscle tone, slowness of movement

→ Parkinson’s & Huntington’s

• Limbic system - NB to emotion, motivation, memory & learning

- More developed in mammals than fish & reptiles

- Allows us to suppress instinctive responses

- Help us to adapt our behaviours reflexively in response to a changing environment

- Comprises 3 central, interconnected cerebral structures:

1. Septum - Involved in anger & fear

2. Amygdala - NB role in emotion, esp anger & aggression

- Stimulation of amygdala results in fear (palpitations, hallucinations, frightening flashbacks)

- Damage can result in maladaptive lack of fear

- Has enhancing effect for perception of emotional stimuli

- People with autism: Limited activation in the amygdala

- 2 other effects of amygdala damage: Visual agnosia & hypersexuality

3. Hippocampus - Essential role in memory formation

- Shaped like a seahorse

- Essential for flexible learning, seeing the relationships between items learned

- NB for spatial memory, keeps track of where things are &b how they are spatially related

→ Monitors what is where

- Korsakoff’s syndrome: Can’t make new memories

also apathy, paralysis of muscles controlling the eye & tremor

Hippocampus is damaged by lack of vitamin B1

→ Alcohol abuse, malnutrition & eating disorders

- Damage affects declarative memory, but not procedural memory

• Thalamus - Relays incoming sensory info through groups of neurons that project into appropriate regions of the cortex

- Most of the sensory info passes through the thalamus

- Located in the centre of the brain, at approximately eye level

- Divided into a number of nuclei (groups of neurons of similar function)

→ Each receiving & relaying info from specific senses

- Helps control sleep & waking

- Malfunctions: pain, tremor, amnesia, language impairment, disruptions of waking and sleeping

- Schizophrenia: Abnormal changes in thalamus

Difficulty filtering stimuli and focussing attention

Can explain hallucinations & delusions

• Hypothalamus - Regulates behaviour related to species survival (fighting, fleeing, feeding & mating)

- Regulates emotions and reaction to stress

- Interacts with limbic system

- Small, located at base of forebrain, beneath thalamus

- NB in controlling many bodily functions

- Plays a role in sleep: Dysfunction of hypothalamus noted in narcolepsy

- NB in functioning of endocrine system

→ Involved in stimulation of pituitary glands through which a range of hormones are released:

Incl growth hormones & oxytocin (bonding & sexual arousal)

The Midbrain

• Helps control eye movement & coordination

• More NB in nonmammals - Main source of control for visual and auditory information (forebrain does this for mammals)

• RAS - Reticular activating system/reticular formation

- Most indispensable of midbrain structures

- Network of neurons responsible for regulation of consciousness

(sleep, wakefulness, arousal, attention to some extent)

- Vital functions such as heartbeat and breathing

- Extends into the hindbrain

- Together with thalamus: essential to us having any conscious awareness of or control of our existence

• Brainstem - Connects forebrain to spinal cord

= hypothalamus + thalamus + midbrain + hindbrain

- PAG: Periaqueductal gray

- Essential for certain kinds of adaptive behaviours

- Stimulation results in: an aggressive, confrontational response/

avoidance or flight response/

heightened defensive reactivity/

or reduced reactivity as in the hopelessness after defeat

- Brain death is based on function of brainstem:

Various reflexes in the head absent for more than 12 hours (eg pupillary reflex) or no electrical activity or

circulation of blood in the brain

The Hindbrain

• Medulla oblongata - Controls heart activity and most of breathing, swallowing & digestion

- Where nerves from the right side of the body crosses over to the left side of the brain & vice versa

- Elongated interior structure located where the spinal cord enters the scull and joins with the brain

- Contains part of the RAS

- Helps keep us alive

• Pons - “relay station” contains neural fibres that pass information from one part of the brain to another

- Name from Latin word for “bridge”: bridging function

- Also contains part of RAS & nerves serving the parts of the head face

• Cerebellum - “Little brain” : Controls bodily coordination, balance and muscle tone

Some aspects of memory concerning posture-related movements

• Prenatal development of human brain - Roughly corresponds with evolutionary development of the brain

• Hindbrain - Evolutionarily the oldest and most primitive part

- 1st part of the brain to develop prenatally

• Midbrain - Newer addition evolutionarily and develops after midbrain prenatally

• Forebrain - Newest addition evolutionarily, develops last prenatally

• Across evolution - Brain weight increased in proportion to body weight

• After birth - Brain weight decreases in proportion to body weight

• Most NB evolutionary trend - Increasing neural complexity of the brain

• Evolution of brain - Enhanced ability to exercise voluntary control over behaviour

- Strengthened ability to plan and contemplate alternative courses of action

Cerebral cortex and localization of function

•Cerebral cortex - NB role in human cognition

- 1-3mm layer that wraps the surface of the brain

- if flattened would take u p 2 sq feet, forms 80% of the human brain

• Creases of the cerebral cortex - Increases the surface area

- Comprises 3 elements : Sulci - Small grooves

Fissures - Large grooves

Gyri - Bulges between sulci or fissures

• Volume of human scull - More than doubled over last 2 million years

→ Allows for expansion of brain, esp the cortex

• Cerebral cortex - Enables us to think

- Enables planning, coordination of thoughts & actions, perception of visual & sound patterns, language use

- “gray matter” primarily comprises gray neural-cell bodies that processes the info received & sent by the brain

(underlying “white matter” is mostly white, myelinated axons)

• Cerebral hemispheres - Left & right halves of the brain

- Appear similar but function differently, specialized for different kinds of activities

• Contralateral information transmission - From one side of the body to the opposite hemisphere

- Eg Motor responses, sensory info from skin, half the info from the eyes

• Ipsilateral information transmission - From One side of the body to same side of the brain

- Eg, odour information, other half of the info from each eye

• Corpus callosum - Dense aggregate of neural fibres connecting the two hemispheres

- Allows direct transmission of info between the two hemispheres

• Some functioning (language) is highly lateralized, but most depends on an integration of the two hemispheres

Hemispheric specialization

• Marc Dax - French doctor, 1836. Beginning of the study of hemispheric specialization

- Treated patients suffering from aphasia, noted that it corresponded with damage to left hemisphere

• Aphasia - Loss of speech

• Paul Broca - French scientist 1961. identified an area called Broca’s area that contributes to speech

• Carl Wernicke - German neurologist studied patiens who could speak but whose speech made no sense

- Wernicke’s area contributes to language comprehension

• Karl Spencer Lashley - “Father of neuropsychology”, research limited by available technology of the times

- Started studying localisation in 1915

- Found that implantations of electrodes in similar-seeming areas of the brain yielded different results

Different locations sometimes yielded the same results

- Subsequent researchers found that specific locations do correlate with specific motor functions

• Roger Sperry - Individual most responsible for modern theory and research on hemispheric specialization

- Argued that each hemisphere behaves like a separate brain

- Severed the corpus callosum of a cat & proved info available to one hemisphere was not available to the other

• Split-brain patiens - Corpus callosum has been severed (eg epileptics)

• Lateralisation - Differs for left-handed people

(95% of right-handers & 70% of left-handers have left-hemisphere dominance for language)

- Less pronounced for women

• Apraxis - Disorders of skilled movements

- Left brain damage

• Left hemisphere - 90% of population’s language functions are predominantly in the left brain

- Also important in movement (see apraxis above)

- Examines past experiences to find patterns (finding patterns NB step to forming hypotheses)

• Right hemisphere - Largely “mute”: Little grammatical or phonetic understanding

- Very good semantic knowledge + involved in practical language use

→ Right hemisphere damage - Difficulty following stories & conversations

- Difficulties in inferring meaning from context

- Difficulties in understanding metaphorical or humorous speech

- Primary role in self-recognition, esp identifying own face

- Spatial visualization ability & spatial orientation tasks

• Composite photograph studies with split-brain patients:

* When asked to report what they see in words - Report what’s on right hand side of picture

* When using left hand to point at what they saw - Point to what’s on left side of picture

• Gazzaniga - Believes hemispheres serve complimentary roles (rather than function completely independently)

- Before split-brain surgery, patients can draw 3d cubes with both hands, after surgery only with their left hands

→ supports idea that the right brain is dominant in our comprehension of spatial relations

- The brain (esp R hemisphere) is organised into relatively independently functioning units that work in parallel

→ These operations - subconscious

- While the operations take place: L hemisphere tries to assign interpretations to the operations

• Other difference between the hemispheres - Some evidence that they think in different ways

- Left brain seems to process information analytically (piece-by-piece, in sequence)

- Right brain seems to process information holistically (as a whole)

Lobes of the cerebral hemisphere

• 4 Lobes - Divide the cerebral hemispheres & cortex into 4 parts

- Largely arbitrary anatomical regions separated by fissures (not distinct units)

- Particular functions are identified with each lobe, but they also interact

- Named after the bones of the scull lying over them

• Frontal lobe - Toward front of brain

- Motor processing & intentional movement

- Higher thought processes: Abstract reasoning, problem solving, planning, judgement

- Involved when sequences of thoughts or actions are called for

- Critical in producing speech

- Involved in personality

- Contains primary motor cortex

* Prefrontal cortex - Front of frontal lobe

- Complex motor control

- Tasks that require integration of info over time

Other lobes are located further from front of the head & specialize in sensory and perceptual activity:

• Parietal lobe - Upper back portion of brain

- Somatosensory processing (touch, pain, temperature & limb positioning in space)

- Consciousness and paying attention

- Contains primary somatosensory cortex ~ Just behind primary motor cortex

~ Gets info re pressure, temperature, texture & pain

~ Larger parts are devoted to the body parts needing sensitivity & fine control than those that don’t

• Temporal lobe - Directly under temples, below parietal lobe

- Auditory processing & language comprehension

~ Complex auditory analysis eg to understand speech or music

~ Specialised: Some parts sensitive to one pitch etc

~ Primarily contralateral , although both sides have some input from each ear

- Retention of visual memories

- Matches new things we see to what is retained in visual memory

• Occipital lobe - Visual processing: Numerous visual areas are each specialized to analyse aspects of a scene

- Contains visual cortex ~ Nerves from middle of eyes cross at optic chiasma

THUS ~ Neural fibres from left side of each eye goes to R side of visual cortex ???

• Projection areas - Areas in the lobes in which sensory processing occurs

- These nerves contain ~ Sensory info projecting to the thalamus

~ Motor info going through spinal cord to PNS (peripheral nervous system)

○ Primary motor cortex - Planning, control & execution of movement (esp movement involving a delayed response)

- Control of movements are located contralaterally on primary motor cortex

- Inverse mapping also occurs from top to bottom

- Info to neighbouring body parts come from neighbouring part of motor cortex

• Homunculi - Depict body parts of a person mapped onto the brain

• Terms for different brain regions:

~ Rostral - Front part of brain (“nasal region”)

~ Ventral - Bottom surface of the body/brain (side of the stomach)

~ Caudal - Back part of body/brain (literally “tail)

~ Dorsal - Upside of the brain (literally “back”)

• Brain - 1/40th of body weight, but uses 1/5th of circulating blood, glucose and oxygen : Supreme organ of cognition

CHAPTER 5 - MEMORY: MODELS & RESEARCH METHODS

TASKS USED FOR MEASURING MEMORY

Recall vs Recognition tasks

• Recall tasks - requires one to produce an item from memory

- Requires expressive knowledge

• Recognition tasks - Requires one to identify an item you have previously been exposed to

- Usually much better than recall

- In a study participants could recognise up to 2 000 items

- Knowing beforehand if a test will be recall or recognition influences learning

- Taps receptive knowledge (receptive = responsive to a stimulus)

• 3 Types of recall tasks:

~ Serial recall - Recalling items in the exact order they were presented

~ Free recall - Recalling items in any order

~ Cued recall - You are shown items in pairs, cued with one item and asked to recall it’s mate

- Also called paired-associates recall

• Relearning - Measuring the no of trials it takes to relearn something that was learnt in the past

- Experience a saving in time compared to the 1st time one learned the info

Implicit vs Explicit memory tasks

• Explicit memory - Conscious recollection

- Differs over the lifespan

• Implicit memory - Using info from memory but not conscious of doing so

- eg filling in missing letters or remembering how to read while reading

- Does not show changes over the lifespan

• 2 tasks that involve implicit memory - Priming & procedural knowledge

• Priming - Used in a lab to study implicit memory using word-completion tasks

- A facilitation of your ability to utilize missing information

• Procedural memory - A memory for process

- Can also be tested in implicit-memory tasks

- eg recalling the procedures for driving

- Sometimes examined in a lab using the rotary pursuit task or mirror tracing (see p191)

- Connected to sleep, increased duration of slow-wave sleep improves procedural memory

→ These methods assume implicit & explicit memory are separate & can be measured by different tasks

• Process-dissociation model - Assumes implicit & explicit memory play a role in almost every response

→ Only one task is needed to measure both processes

Intelligence and the importance of culture in testing

• We need to consider context when testing intelligence

• Culture-relevant tests - Measure skills and knowledge that relate to the cultural experiences of the tested

→ Tests measuring skill in pragmatic aspects of everyday life

• Culture-relevant content is remembered more effectively than non-relevant content

• If tests are not designed to minimize effects of culture - Key to cultural differences might be use of metamemory

strategies rather than actual structural. differences in memory

MODELS OF MEMORY

The traditional model of memory

• Mid-1960’s - Two structures of memory is suggested, Primary (for temporary memory currently in use)

Secondary memory (stores memories permanently)

• Alternative model - Suggested by Richard Atkinson and Richard Shiffrin: 3 Memory stores:

Sensory store - Stores limited amounts of info for very brief periods

Short-term store - Can store info for longer, but also has limited capacity

Long-term store - Large capacity & can store memories for very long/indefinitely

• “stores” - Hypothetical constructs not physiological structures

Sensory store

• Initial repository of information that later enter the other stores

• Iconic store - Discrete visual sensory register that holds info for very short periods

- Info is stored in the form of icons (visual images that represent something)

• Sperlings Discovery - Initial discovery of the iconic store

(see p 194 for details about the experiment)

- Information fades very quickly from the iconic store

- We are unable to distinguish the environment from our iconic memory

~ Problem with the experiment - Output interference

(verbally reporting multiple symbols could interfere with reports of iconic memory)

Short-term store

• Unlike sensory memory, we do have introspective access to the short-term memory store

• Holds memories - Few seconds to few minutes, typically 30 seconds unless rehearsed

• Information is stored acoustically (mostly)

• Can store about 7 items (+/- 2) - Larger amounts can be remembered by grouping them into 7 chunks

- Words with many syllables, or delays, reduce the capacity for recall

• Can store about 4 items of visual information (experiment description on p198)

Long-term store

• Memories that are kept in the long term/indefinitely

• We don’t know the capacity of long-term memory, or how to test it.

•Penfield - Found stimulation of different parts of the brain occasionally triggered childhood memories

→ This suggests long term memories may be permanent

Criticism - Few patients experienced this

- Patients may have been inventing memories

- Other research, esp wit older patients, found contradictory evidence

• Permastore - Very long-term storage of info (eg a foreign language/mathematics)

- Remembering childhood street names suggests info passively learnt can also be in the permastore

• Some researchers believe the permastore to be a separate system, others think long-term memory accounts for it

The levels-of-processing model

• Radical departure from the three-stores model

• Memory doesn’t comprise separate stores - Varies along a continuous dimension in terms of depth and encoding

→ Thus there are infinite “levels of processing” with no distinct boundaries

• Elaboration - Successively deeper understanding of material to be learned

• Emphasis - Processing as key to storage

- Level at which info is stored depends on how it is encoded

- Deeper level of processing = higher probability of retrieval

• This effect is applicable to nonverbal stimuli as well

• Schizophrenics - Often have memory problems because they do not process words semantically

• Levels of processing:

Physical - Relates to the apparent features of the letters

Phonological - Sound combinations associated with the letters (eg rhyming)

Semantic - Meaning of the word

Self-reference - Relating the word to one’s self

• Self-reference effect - High levels of recall when a word is related meaningfully to the participant.

• Criticism of LOP - Levels may involve a circular definition

(Level is defined as deeper because retention is better,

but info is viewed as retained better because the level is deeper)

- Some paradoxes in retention

(sometimes focussing on superficial sounds have better retention than focussing on underlying

meanings)

• Revised LOP model - Sequence of levels of encoding may not be as NB as thought before

- 2 other processes may be more important:

~ How people process (elaborate) the encoding of an item

~ The way an item is retrieved

→ Retrieval results are better if these match

• 2 Strategies for elaboration:

~ Within-item elaboration - Elaborates the encoding of an item ito its characteristics

~ Between-item elaboration - Relating each item’s features to features of items in memory.

An integrative model: Working memory

• Most widely used & accepted model today

•Key feature - Role of working memory

• Working memory - Holds most recently activated/conscious portion of the long-term memory

- Moves the activated elements in and out of temporary memory storage

The components of working memory

• Integrative model of memory - Synthesises working-memory model with LOP framework

- LOP framework is an extension of the working-memory model (not replacement)

• 5 Elements:

* Visuospatial sketchpad - Briefly holds some visual images

* Phonological loop - Briefly holds inner speech (for verbal comprehension & acoustic rehearsal)

- eg for sounding out new words & solving word problems

- Amount of info it can manipulate is limited (fewer long words than short ones)

2 Components:

~ Phonological storage - Holds information in memory

~ Subvocal rehearsal - Used to put info into memory

- Articulatory suppression - When subvocal rehearsal is inhibited

→ info is not stored

- More pronounced when info is presented visually

* Central executive - Coordinates attention and governs responses

- Critical to working memory → gating mechanism that decides what info will be processed further

- Decides what resources to allocate and how to allocate them

- Involved in higher-order reasoning & comprehension

- Central to intelligence

* Subsidiary slave systems - Perform other cognitive or perceptual tasks

* Episodic buffer - Limited-capacity system

- Integrates info from components of the working memory into a unitary episodic representation

- Puts everything together so it makes sense to us

- This allows us to solve problems & re-evaluate experiences with more recent knowledge

NB: Three-store model emphasises - Structural receptacles for stored information (passive process)

Working-memory model focus - Functions of working memory in governing processes of memory

→ These processes include encoding & integration of info

Neuroscience and working memory

• Neuropsychology - Supports distinction between working memory and long-term memory

- Evidence of a brief memory buffer

• PET scans - Show evidence for different areas involved in different aspects of working memory:

* Phonological loop - Left hemisphere of lateral frontal & inferior parietal lobes + temporal lobe

* Visuospatial sketchpad - Short intervals of retention activates areas of occipital & right frontal lobes

- Longer retrieval intervals activate areas of parietal & right frontal lobes

* Central executive - Mostly the frontal lobes

*Episodic buffer - Bilateral activation of frontal lobes & portions of temporal lobes, incl left hippopcampus

Measuring working memory

a) Retention delay task - Shown a stimulus, then after a delay must say if the new stimulus is old or new

b) Temporally ordered working memory load task - Same as above but with a series of items as 1st stimuli

c) Temporal order task - Shown a series of stimuli, then a delay, then 2 stimuli, must say which appeared more recently

d) n-back task - Shown a series, and at intervals have to say what the stimuli was n times ago

e) Temporally ordered working memory task/digit-span task - Repeat the stimuli in same or opposite order as given

f) Temporally ordered working memory load task - Do a set of simple arithmetic problems, then repeat the results in the correct order

• A secondary task can be involved (eg random number generation) to study the central executive.

- Shows how mental resources are allocated

Intelligence and working memory

• Working memory - An NB part of intelligence.

• Ability on some working memory tasks correlated to performance on general ability and intelligence tests

Multiple memory systems

• Working-memory model - Consistent with idea that multiple systems are involved in storage & retrieval of info

• Semantic memory - General world knowledge

- Memory for facts not unique to us and that are recalled without a particular temporal context

• Episodic memory - Personally experienced episodes/events

- Also used for learning lists of words as the context of learning is associated with the list

• Neurological investigations support distinction between semantic & episodic memory

- Electrical-stimulation studies, studies of patients with memory disorders, cerebral blood flow studies

- eg lesions in the frontal lobe affect recollection re when a stimulus was presented

BUT - distinction is often fuzzy, episodic memory may be a specialized form of semantic memory

• Dissociations - separate and distinct areas are found for different functions

- Are found between semantic & episodic memory (some patients have impairment to only one)

• Taxonomy of memory systems ito dissociations:

Declarative (explicit) memory : Nondeclarative (implicit) memory

* Semantic * Procedural memory

* Episodic * Priming effects

*Simple classical conditioning

* Habituation

* Sensitization

* Perceptual after effects

• Another view sees 5 memory systems:

Episodic, semantic, perceptual, procedural & working memory

A connectionist perspective

• PDP - Parallel distributed processing, a connectionist model

- Key to knowledge representation lies in the connections among nodes stored in memory, not in individual nodes

- Activation of one node prompts activation of additional nodes

- Fits with idea that working memory comprises the activated portion of long-term memory

- Activation spreads through nodes within the network

- Spreading continues as long as activation doesn’t exceed the limitations of the working memory

• Prime - A node that activates a connecting node

• Priming effect - Resulting activation of the node

- eg priming as an aspect of implicit memory

* No agreement about mechanisms for the priming effect

• Connectionist model - Intuitive appeal because it incorporates several contemporary notions about memory

- Some support from laboratory studies

- Explains: Priming effects, skill learning, & several other memory phenomena

- A bottom-up theory

BUT fails to explain recall & recognition memory following a single episode/exposure

~ Working memory - The activated portion of long-term memory, operates through some amount of parallel activation

~ Spreading activation - Parallel activation/priming of multiple links among nodes within a network

EXCEPTIONAL MEMORY AND NEUROPSYCHOLOGY

Outstanding memory: Mnemonists

• Mnemonist - Has extrodinarily keen memory ability, usually based on using special techniques

* “S” - Most well-known mnemonist

- Had synesthesia, so each word had a range of sensory connections

- Relied primarily on visual imagery

* VP - Memorised numbers by transforming them into dates & remembering what he did on that day

* SF - Converted numbers into running times, and struggled to remember numbers that couldn’t be

- Implies someone with normal memory can practice expertise in at least some domains

→ all 3 - remembered abstract info by making it concrete & meaningful, and sometimes connected to the senses

• We also more easily encode new information if it is similar to what is already stored

• Hypermnesia - “unforgetting” The process of retrieving memories that seem to have been forgotten

- Achieved by trying many diverse retrieval cues

- Risk of generating a memory

Deficient memory

Amnesia

• Severe loss of explicit memory

•Retrograde amnesia - Los of memory prior to the trauma

- Memories typically return from the more distant to the more recent past

- Events right before the trauma are often never recalled

• Anterograde amnesia - Inability to remember events after the trauma. - HM (memento)

• Infantile “amnesia” - Inability to recall events from when we were very young

- Some question whether this is truly a form of amnesia

Amnesia and the Explicit-Implicit memory distinction

• Insights from amnesia research - Highlights distinction between implicit and explicit memories

• Explicit memory - Ability to reflect consciously on prior experience

- Impaired in amnesiacs

• Implicit memory - Ability to demonstrate prior learning in an apparently automatic way

- Eg priming, word-completions, procedural memory for skill-based tasks

- Typically not impaired in amnesiacs

• Procedural knowledge tasks - Not impaired

• Decarative memory tasks – Impaired

Amnesia and neuropsychology

• By matching locations of lesions with particular deficits in function - better understanding of how memory functions

• An association between lesion location and disruption of function

- Does not mean that area is solely responsible for the function

- Many alternative hypotheses can explain the link between a particular lesion & a dysfunction

• Double dissociations - When people with different kinds of conditions show opposite patterns of deficits:

eg a lesion in brain structure 1 leads to impairment in memory function A but not memory function B

AND a lesion in brain structure 2 leads to impairment in memory function B but not memory function A

- eg Lesions in left parietal lobe - Inability to retain info in short-term memory,

no long-term memory impairment

Lesions in medial temporal regions - Normal short-term memory of verbal materials,

but serious impairment in storing verbal material in long-term memory

- Strong support that particular structures in the brain play particular vital roles in memory

Alzheimer’s disease

• Causes dementia as well as progressive memory loss

• Dementia = Loss of mental function severe enough to impair one’s everyday life

• Leads to atrophy of the brain - Esp in hippocampus and frontal & temporal brain regions

• Plaques - Dense protein deposits outside the nerve cells

• Tangles - Pairs of filaments twisted around each other : - Found in cell body and dendrites & shaped like a flame

• Diagnosed when memory is impaired and there is at least one other area of dysfunction

• Symptoms onset are gradual, and progression is continuous and irreversible.

• Early onset Alzheimer’s - Familial, due to a genetic mutation

• Late onset Alzheimer’s - Complexly determined & related to a variety of genetic & environmental influences

•Earliest signs - Impairment of episodic memory

- Trouble remembering things learnt in a temporal or spatial context

- Semantic memory next

• Show no difference between emotionally charged and not charged memories

• Nondeclarative memory is spared until the very late stages

• End result is inevitably death

How are memories stored?

• Cerebral cortex - NB role in long-term storage of information

•Hippocampus - Key role in encoding of declarative information

- Main function~ Integration of separate sensory information + spatial orientation & memory

- Transfer of newly synthesized information into long-term structures supporting declarative information

- Could provide means for cross-referencing info stored in different parts of the brain

- Crucial role in complex learning

- Significant role in recollection of information

•Basal ganglia - Primary structures controlling procedural knowledge : - NOT involved in controlling the priming effect

• Cerebellum - Key role in memory for classically conditioned responses

- Contributes to many cognitive tasks in general

• Amygdala - Associated with emotional events

- Involved in recall of emotionally charged events, but not of uncharged events

- NB role in memory consolidation, esp of emotional experiences

Microlevel: • Long-term potentiation - Repeated stimulation of a neural pathway strengthens the likelihood of firing

- Potentiation refers to the increase in activity

- At a synapse there are changes in the dendrites of the receiving neuron,

making the neuron more likely to reach the threshold for firing again

- Indicates neurons in the hippocampus may be able to change their interactions (are plastic)

• Some neurotransmitters disrupt memory storage, others enhance it:

* Serotonin & acetylcholine - Enhances neural transmission associated with memory

* Norepinephrine maybe too

* Acetylcholine - Low levels in Alzheimer’s patients

• Korsakoff syndrome - Severe & prolonged alcohol abuse

- Disrupts the activity of serotonin

- Anterograde amnesia, impaired formation of memories

- usually accompanied by at least some retrograde amnesia

- Linked to damage in the diencephalon (region of thalamus and hypothalamus)

• Some hormones - Stimulate increased availability of glucose in the brain

- This enhances memory function

- Associated with highly arousing events

eg traumas, achievements, first time experiences, crises, peak moments

CHAPTER 6 - MEMORY PROCESSES

ENCODING AND TRANSFER OF INFORMATION

Forms of encoding

Short-term storage

• Conrad experiment - Shows short term memory primarily uses an acoustic rather than visual code (p230)

- Errors in retrieval primarily reflect confusions in sound

• Semantics - Makes a difference, but not much

• Visual encoding - Very fleeting, prone to be forgotten quickly

THUS - Initial encoding is primarily acoustic, but other forms of encoding may be used under some circumstances.

Long-term storage

• Most info stored in long-term memory - Primarily semantically encoded (by meaning)

• 2 experiments - In a recognition task after seeing a list of words, semantically related distracters were more often falsely “recognised”

- In a list containing related words, randomly mixed, people remembered the related words together in

free-recall, even though they were presented randomly.

• Levels of processing - Also influences encoding in long-term storage

- More information is stored when using semantic encoding strategies

→ Not when people are autistic, implying they do not encode information semantically as much

~ Their Brocca’s area shows less activation

→ Indicates Brocca’s area may be related to semantic deficits in autistic patiemnts

• Visual encoding - Also plays a role

• Brain areas involved in encoding - Not necessarily involved in retrieval

• Acoustic information - Can also be encoded in long-term memory

→ Considerable flexibility in how we store information

Most useful question - When do we encode in which ways

Transfer of information from short-term memory to long-term memory

• 2 key problems when transferring info from short- to long-term memory: Interference and decay

• Interference - When competing information interferes with our storing of info

- eg getting confused between two movies with the same actor

• Decay - When we forget facts just because time passes

• Means of moving information to long-term storage - Depends on if it involves declarative or non-declarative memory

• Some forms of nondeclarative memory decays quickly - Priming & habituation

• Other forms are retained better esp when - Repeated practice (of procedures)

- Repeated conditioning (of responses)

• Ways to enter information into long-term declarative memory - Deliberately attending to the info to comprehend it

- Consolidation

- Metamemory strategies

• Consolidation - Making connections/associations between the new information & what we already know

- By integrating new data into existing schemas

- The process can continue for years after the initial experience

- During consolidation, our memory is susceptible to disruption & distortion (ECT studies)

• Metamemory - Reflecting on own memory processes with the goal of improving memory

- Esp important when using rehearsal

- One component of metacognition (ability to think about & control own processes of thought)

Rehearsal

• Repeated recitation

• Effects of rehearsal = “Practice effects”

• Can be overt (aloud and obvious) or covert (silent)

• Elaborative rehearsal - Essential to move information into long-term storage

- Elaborates the items by meaningfully integrating them into existing knowledge, OR

by more meaningfully connecting the items to each other making them more memorable

• Maintenance rehearsal - Simple repetition

- Temporarily maintains info in short-term memory, without transferral to long-term storage

• Spacing effect - Memory for information depends on how it is acquired

- Distributed practice ~ Learning in sessions spaced over time

Massed practice ~ Learning in sessions crammed together in a short space of time

- The greater the distribution of learning trials over time, the better it is remembered

- Linked to the process by which memories are consolidated into long-term memory

~ At each learning session the context for encoding varies, and different strategies are used

~ Influence of sleep on memory may also play a role

• REM - Stage of sleep characterised by dreaming and increased brainwave activity

- Disruptions of REM after learning interfered with memory consolidation

- Memory processes in hippocampus ~ Influenced by production&integration of new cells into neuronal network

→ Prolonged sleep deprivation affects such cell development negatively

- Highlights importance of biological factors in consolidation of memory

Neuroscience and memory consolidation

• Hippocampus - NB for memory

• Hippocampal cells that are activated in initial learning - Reactivates during subsequent sleep

→ As if they are replaying the initial learning episode to achieve consolidation

• During this increased cell activity - Hippocampus shows decreased acetylcholine

If given acetylcholine during sleep - Impaired memory consolidation for declarative memory (NOT procedural)

• Hippocampus - Acts as rapid learning system

- Temporatily maintains new experiences until they can be appropriately assimilated

• Integrating new experiences too rapidly - Disruptions in long-term memory systems

Distributed practice = Repeated exposure interspersed with repeated reactivation during sleep

• Consolidation - Makes memories more resistant to interference or decay

- When a memory is returned to consciousness, it may return to a more unstable state.

→ Reconsolidation - Same as consolidation, but is completed on previously encoded information

- Not applied to every memory, but to newly consolidated material

Organisation of information

• Stored memories are organised

• Mnemonic devices - Techniques to memorise lists of words

* Categorical clustering - Clustering into categories

* Interactive images - Imagine the objects interacting in some way

* Pegword system - Associate each word with a word on a previously memorised list

& form an interactive image between the two.

* Method of loci - Visualise walking around an area with landmarks & link the landmarks with items

* Acronyms - Devise a word in which every letter stands for an item

* Acrostics - Form a sentence to help remember the words

* Keyword system - Image that links the sound and meaning of a foreign word with a new one. (p239)

• For free recall & serial recall - Interactive imagery, method of loci & pegword system

→ more effective than elaborative rehearsal of imagery for isolated items

~ benefits of training more pronounced for serial recall than free recall

• For free recall - Imagery of isolated items modestly more effective than elaborative (verbal) rehearsal

For serial recall - Elaborative (verbal) rehearsal modestly more effective than imagery of isolated items

• Effectiveness of encoding - Influenced by kind of task required at recall

• Forcing functions - Physical constraints that keep us from acting without considering the thing to be remembered

(putting car keys in the fridge to remember the mice)

• Retrospective memory - Remembering the past

Prospective memory - Remembering to do something in the future

- Also subject to decline with age

- In laboratory, older adults show decline, but outside the lab they perform better than young adults

→ May be due to tendency to rely more on strategies to aid remembering as we age

RETRIEVAL

Retrieval from short-term memory

Parallel or serial processing?

• Parallel processing - Simultaneous handling of multiple operations

- Items in short term memory retrieved all at once, not one at a time

- In the Sternberg memory scanning task ~ Response times should be the same

regardless of the size of the positive set

(Because all comparisons are done at once)

• Serial processing - Operations are done one after another

- Should take longer to retrieve more items

Exhaustive or self-terminating processing?

• If processing were serial - 2 ways to gain access to stimuli:

* Exhaustive serial processing - Test digit is checked against all digits in positive set,

even if a match is found partway through.

- All positive responses would take the same amount of time

* Self-terminating serial processing - Test digit is checked only until a match is found

- Response time would vary depending on where in the positive set the match is

The winner - a Serial Exhaustive Model - with some qualifications

• Response times increased linearly with set size, but were the same regardless of serial position

• Mean response times for positive & negative sets were the same

BUT a parallel model could also account for response times

Mathematically it is impossible to distinguish parallel from serial models unequivocally (p244 for explanation)

Retrieval from long-term memory

• Difficult to distinguish storage from retrieval phenomena - People do better in a cued recall test than in free recall

→ Implying more words were stored than the free recall test alone would have indicated

→ Apparent memory failures could be from retrieval rather than storage failures

• Categorisation can dramatically improve retrieval

• Khader study- Material processed in certain cortical areas activates those same areas during long-term memory recall

- Abstract words were connected to either faces or a spatial position

- During recall different cortical regions were activated

• Difficult to distinguish between availability & accessibility of items

* Availability - Presence of information in long-term storage

* Accessibility - Degree to which we can gain access to stored information

Intelligence and retrieval

• Speed of information processing - Influences initial recall

- Declines in older participants

- Not related to long-term learning

• Long term retention - Preserved in older participants

- Mediated by cognitive processes other than speed of processing (eg rehearsal strategies)

PROCESSES OF FORGETTING AND MEMORY DISTORTION

Interference theory

• When competing information causes forgetting

• Retention interval - Time between presentation of stimuli and recall

• Counting backwards during retention interval interfered with recall from short-term memory

→ Supports interference theory

• Retroactive interference - (Retroactive inhibition)

- When new information impedes recall of previously learned info

- Caused by activity occurring after we learn something but before we recall it

• Proactive interference - (Proactive inhibition)

- When material learned in the past impedes learning of new material

- Interfering material occurs before learning of to-be-remembered material

- Increases if time between encoding and retrieval increases

- Increases as amount of prior learning increases

- Stronger effect in older adults.

- Associated with activation of the frontal cortex, esp Brodman 45 in left hemisphere

- Less pronounced in alcoholic patiens

→ Suggests they have difficulty integrating old & new information

• Brodman area 45 - Likely involved in binding of information into meaningful groups.

• Release form proactive interference - Enhancement in performance when type of info to recall changes

• Serial-position curve - Probability of recall of a word given its serial position in a list

• Recency effect - Superior recall of words near or at the end of a list

(Words at end are subjected to proactive, but not to retroactive interference)

• Primacy effect - Superior recall of words at or near the beginning of a list

(Words at beginning of list are subjected to retroactive, but not proactive interference)

• Middle words - Subjected to proactive and retroactive interference

- Worst recall

Decay theory

• Passage of time causes forgetting

• Information is forgotten due to the gradual disappearance, rather than displacement, of the memory trace

• Difficult to test - Participants tend to rehearse

- Techniques to prevent rehearsal could cause interference

• Recent-probes task - Research paradigm that doesn’t encourage rehearsal (p252 for description)

• Decay has relatively small effect on forgetting in short-term memory

- Interference accounts for most of the forgetting

THE CONSTRUCTIVE NATURE OF MEMORY

• Memory retrieval is not just reconstructive - Using strategies to retrieve original memory traces,

rebuilding the original experience as basis for retrieval.

• Constructive - Prior experience affects how & what we recall

Autobiographical memory

• Memory of an individual’s history

• Constructive - One remembers a reconstruction, rather than actual events

• Diary studies

• People with positive self-esteem - recall more positive events

• Depressed people recall more negative memories

• When people misremember - They tend to be wrong regarding minor & marginal aspects

• Flashbulb memories - Very vividly “imprinted” memories of momentous moments

- A memory is likely to become a flashbulb memory if ~ It is important to the individual

~ It is surprising

~ It has an emotional impact

- Some suggest they are vividly recalled due to emotional intensity

- Others argue vividness of recall is the result of rehearsal ~ We go over and over such NB events in our minds

→ Accuracy of recall may diminish while perceived vividness increases

- Study of 9/11 show 70% of people remember seeing the 1st plane hit, but footage wasn’t available till next day

- Rate of forgetting is faster in 1ast year, then slows down ~ content becomes more stable later on

- Emotional reactions not as well remembered as nonemotional features such as location

- Memory processes for flashbulb memories same as for other memories

• Medial temporal lobe NB for autobiographic memory

Memory distortions

Shachter’s “seven sins” of memory:

1. Transience - Memory fades quickly

2. Absent-mindedness - Eg forgetting what you were looking for

3. Blocking - Something you know you should be able to remember, but can’t

eg someone’s name or tip-of-the-tongue words

4. Misattribution - Can’t remember sources of information, or think we saw something we didn’t

5. Suggestibility - People can think they remember seeing something if it is suggested to them

6. Bias - eg Remembering past pain because they are in pain now

7. Persistence - People remember inconsequential things as if they were consequential

(eg one failure instead of many successes)

The eyewitness testimony paradigm

• Eyewitness testimony - May be most common source of wrongful convictions

- Errors caused more than ¾ of convictions in the 1st 180 cases exonerated through DNA evidence

- Often an NB determinant of whether a jury will convict

→ esp if witness appears very confident of their testimony

• Loftus eyewitness study - Showed susceptibility of memories to distortion

• Line-ups - People tend to think the perpetrator must be in the line-up, and feel they must choose someone

- Identities of the non-perpetrators also influences the witness

- Confessions also led witnesses to suddenly identify as perpetrator the one who confessed

- Feedback affected testimony

• Post-identification feedback effect - People said they were confident of their choice if they were told they made the

right choice, but if told they made a mistake they say they weren’t sure.

• Eyewitness identification - Esp weak when dealing with racial groups other than self

- Seems to be a problem with encoding rather than remembering stored faces

- Accuracy decreases as stress increases

• Prosecutors - Tend to over estimate eyewitness testimony reliability

& underestimate the role of eyewitness testimony in wrongful convictions

• Children - More susceptible to suggestive questioning

- Tend to give adults the answers the child thinks the adult wants to hear

- Will answer yes/no to a yes/no question even if they don’t know

(unless “I don’t know” is explicitly stated as an option)

- Make more mistakes when a uniformed officer is present

• Suggestive interviews - Cause biases in memory, ESP when the interview takes place close to the event

- People are usually interviewed by police soon after the incident

• Suggestions to improve identification accuracy:

~ Present only one suspect at a time

~ Make sure all people in the line-up are reasonably similar to each other

~ Caution witnesses that the suspect may not be in the line-up at all

• Advise jurors that confidence does not equal accuracy

The effect of context on memory

• Cognitive contexts influence the processes of encoding, storage & retrieval

• Existing schemas - Provide a context for encoding, storage and retrieval

- Makes organisation & integration relatively easy

- Experts have more elaborate schemas than novices

• Expertise - Enhances confidence in existing memories

• Mood & state of consciousness - May provide a context that affects later retrieval of semantic memories

• People suffering from depression - Tend to have deficits in forming and recalling memories

• External context also influence recall

• Infants also show context effects

• Encoding specificity - Interaction between context for encoding & context for retrieval

- What is recalled depends on what is encoded

• When people generate own cues for retrieval, they are more potent than when the cues are generated for them

• Compatible & distinctive cues work best.

• In cued recognition tests people recognised the cues more than the words themselves.

CHAPTER 11 - DECISION MAKING AND REASONING

JUDGMENT AND DECISION MAKING

Classical decision theory

• Earliest models of how people make decisions - Mostly devised by economists, statisticians, philosophers

- Reflect the strengths of an economic model

eg using mathematical models for human behaviour

The model of economic man and woman

• 3 assumptions:

~ People are fully informed re all possible options and all possible outcomes of these options

~ They are infinitely sensitive to the subtle distinctions between the options

~They are fully rational in their choices (They maximise something of value)

Subjective expected utility theory

• Makes greater allowance for the psychological makeup of the decision maker

• Goal of human action - Seeking pleasure and avoiding pain

• In doing so we calculate 2 things:

Subjective utility - Based on subjective judgment of utility/value

Subjective probability - Subjective estimation of likelihood (rather than objective statistical computations)

Human decision making is more complex than this

Heuristics and biases

• To make a decision in a reasonable timeframe - We need to reduce available info to a manageable amount

• Heuristics - Allow us to examine fewer cues/deal with fewer pieces of information

- Lightens the cognitive load at the cost of a greater chance for errors

Heuristics

• Satisficing - We select the first option that is good enough to meet our minimum requirements

- Use of this increases when there are limited working-memory resources

- Used in industrial contexts where too much information impairs the quality of decisions

• Bounded rationality - We are rational, but within limits

• Elimination by aspects - We eliminate alternatives by focussing on aspects of each alternative

• We use these methods to narrow our options, then consider the remaining options more carefully

• Conditional probability - The likelihood of one event, given another

- Formula for calculating this is Baye’s theorem (usually not used in everyday contexts)

• Representativeness heuristic - We judge the probability of an uncertain event according to:

1. How obviously it is similar to the population from which it is derived

2. The degree to which it reflects the salient features of the process by which it is generated (eg randomness)

- We reason in terms of whether something appears to represent a set of accidental occurrences,

rather than considering the true likelihood of an occurrence

- Makes us vulnerable to magicians, charlatans & con artists

- Easy to use and often does work

- We mistakenly believe small samples share the characteristics of the larger population

- We use this heuristic more when we are highly aware of anecdotal evidence based on a very small sample

- Fail to understand the concept of base rates

~ Base rates - prevalence of an event/characteristic within it’s sample of events/characteristics

(truck drivers vs ivy league professors in audio lecture example)

• Availability heuristic - We judge based on how easily we can recall “relevant instances” of a phenomenon

- People judge themselves as having done most of the work in a partnership

- People fear flying more than driving

- Judge there to be more words ending in -ing in a passage than ending in -_n_

• Anchoring-and-adjustment - People adjust their evaluation based on reference points called end anchors

- Adjustment made in response of an anchor is bigger when the anchor is rounded rather than a precise value

• Framing - The way options are presented influences the selection of an option

- We tend to choose options that demonstrate risk aversion when there are potential gains

We choose small, certain gains over larger, uncertain ones,

(unless the uncertain gain is much greater or only slightly less than certain)

- Framing effects are less persuasive when they come from sources of low credibility

Biases

• Illusory correlation - We see events/attributes and categories as going together, even when they don’t

- We se cause-effect relationships where there are none

- We use prejudices to form and use stereotypes

• Overconfidence - An over-evaluation of own skills, knowledge or judgment

- People may not realise how little they know, or how unreliable their sources are,

or simply don’t want to consider that we may be wrong

• Hindsight bias - When we look at a situation retrospectively, we believe we can see all the signs and events

leading up to a particular outcome.

- Hinders learning ~ Impairs ones ability to compare expectations with outcomes

- Experience does not reduce this bias

Fallacies

• Goes hand in hand with heuristics - Application of a heuristic can lead to fallacies in thinking

The gambler’s fallacy and the hot hand

• The belief that the probability of a random event is influenced by previous random events

(After losing 5 times a gambler feels he is “due” to win)

• The representative heuristic gone wrong

• Hot hand - Opposite of the gambler’s fallacy

- Belief that a certain course of events will continue

eg people think a player’s chances of making a basket are bigger after making a previous shot

Conjunction fallacy

• Availability heuristic gone wrong

• Gives a higher estimate for a subset of events than for the larger set containing the subset

(Thinking it is more likely that a certain type of person is a feminist librarian than a librarian)

• Representativeness heuristic - can also lead to conjunction fallacy during probabilistic reasoning (p455 for examples)

Sunk-cost fallacy

• Deciding to continue to invest in something because one has invested in it before & hope to recover one’s investment

• Continuing investment rather than cutting your losses and giving up

The gist of it: Do heuristics help us or lead us astray

• Heuristics often lead to very good decisions

eg take-the-best heuristic - Picking one attribute that matters most and choosing the option that maximises that

- Often leads to better decisions than much more complex models

• FFH - Fast-and-frugal heuristics

- Decisions made rapidly based on a small fraction of information

- Set a standard of rationality that considers constraints incl time, information & cognitive capacity

Also considers the lack of optimum solutions & the environment in which decision-making takes place

- Used from sports to selecting lunch to a dr’s decision whether to prescribe medication for a depressed patient

• Heuristics and biases - Show importance of distinguishing betw intellectual competence & performance in daily life

- Someone may score high on an IQ test but still show same biases & faulty reasoning

- People often fail to utilise their intellectual competence in daily life

• Street smart - Mindful of applying our intelligence to daily problems

Opportunity costs

• The price paid for availing oneself of certain opportunities

• Taking these costs into account in an unbiased way - NB when making decisions

Naturalistic decision making

• Decision making in natural environments

• Decision making - Hard to reproduce in a laboratory

• Real decisions - Often have high stakes

- Studied in real life situations that share certain features:

~ Ill-structured problems, changing situations, high risk, time pressure & sometimes team environments

• Some models - Are used to explain performance in high stakes situations

- Consider the cognitive, emotional & situational factors of skilled decision makers

- Provide a framework for advising decision makers

Group decision making

Benefits of group decisions

• Working in a group - can enhance the effectiveness of decision making

• Group benefits from the expertise of each member

•Increase in resources & ideas

• Improved group memory over individual memory

• Groups that are successful in decision making share some characteristics:

~ Small size

~ Open communications

~ Members share a common mind-set

~ Members identify with the group

~ Members agree on acceptable group behaviour

• In juries - More info is shared when the group is made up of diverse members

• Interpersonal influence is NB - People employ tactics to influence other’s decisions

- Most influential tactics = Inspirational and rational appeals

Groupthink

• Premature decision making - Usually as a result of group members trying to avoid conflict

• Results in - Sub-optimal decision making that avoids non-traditional ideas

• Conditions that lead to groupthink:

1. Isolated, cohesive and homogenous group

2. No objective and impartial leadership (within the group or outside it)

3. High levels of stress impinge on the group decision-making process.

• Anxiety - Group members less likely to explore new options & more likely to try avoid conflict

• Groups responsible for foreign policy decisions - Excellent candidates for groupthink:

- Likeminded & isolated

- Try to meet specific objectives & believe they can’t afford to be impartial

- High stress levels

• 6 symptoms of groupthink:

1. Closed mindedness - Not open to alternative ideas

2. Rationalization - Goes 2great lengths 2justify the process & product of its decision making distorting reality to be persuasive

3. Squelching of dissent

4. Formation of a “mindguard” - One person appoints self as keeper of group norm & ensures compliance

5. Feeling invulnerable - Group believes they must be right due to their intelligence & information

6. Feeling unanimous - Members believe everyone unanimously shares the opinion of the group

• Insufficient examination of alternatives + inadequate examination of risks + incomplete seeking of alternatives

= defective decision making

Antidotes for groupthink

• Leader should - Encourage constructive criticism

- Be impartial

- Ensure that members seek opinions of people outside the group

- Prevent spurious conformity to a group norm

• Group should form subgroups - Meeting separately to consider alternatives

Neuroscience of decision making

• Prefrontal cortex, esp anterior cingulate cortex - Active during decision-making process

• Parietal regions - Also activated, and amount of activation is influenced by amount of gain associated with a decision

• Anterior cingulate cortex - Involved in consideration of potential rewards

- Increased activation associated with suboptimal decisions

also with decisions made with lowest confidence & taking the longest to make

→ Suggests this region is involved in comparison & weighing of possible options

DEDUCTIVE REASONING

• Reasoning - The process of drawing conclusions from principles & evidence

What is deductive reasoning?

• Reasoning from general statements to a specific conclusion

• Reaches a logically certain conclusion

• Based on logical propositions

• Often involves reasoning from a general statement to a specific application of that statement

Conditional reasoning

What is conditional reasoning?

• Must draw a conclusion from an if-then proposition

• Deductive validity - Does not imply truth

Truthfulness of the conclusion - Depends on truthfulness of the premises

Deductively valid arguments:

Modus Ponens If p then q p, therefore q

Affirming the antecedent If you are a mother, you have a child You are a mother, therefore you have a child

Modus Tollens If p then q NOT p, therefore NOT q

Denying the consequent If you are a mother, you have a child You don’t have a child, therefore u are not a mother

Deductive fallacies:

Denying the antecedent If p then q NOT p, therefore NOT q

If you are a mother, you have a child You are not a mother, therefore you don’t have a child

Affirming the consequent If p then q NOT p, therefore NOT q

If you are a mother, you have a child You have a child, therefore you are a mother

The Wason selection task (see p464 for full description of task)

• Cards with odd and even number on one side, and vowels and consonants on the other

• Used to test people’s reasoning

• Most people test for modus ponens argument

• Many failed to test for modus tollens

• Some try to deny the antecedent

Conditional reasoning in everyday life

• People know to use modus ponens, but forget about modus tollens

• People tend to deny the antecedent or deny the consequent

• Even training in deductive reasoning doesn’t really improve people’s use of it in various situations

• Everyday situations invite inferences that may be logical fallacies, but which are common sense

• People fare better if the contextual information converts the problem from abstract reasoning to an everyday situation

Influences on conditional reasoning

• Beliefs regarding plausibility - Influence whether people use the modus tollens argument

(More likely to check if a 16yo is drinking beer than a 4 year old)

• In real situations - People use pragmatic reasoning schemas rather than formal inference rules

• Pragmatic reasoning schemas - General organising principles/rules related to goals

(permissions, obligations, causations)

- Also called pragmatic rules

- Not as abstract as formal logic rules

- Broad enough to apply to a variety of situations

- Thus prior beliefs affect reasoning

• Perspective effects - When perspective influences reasoning

Evolution and reasoning

• What kind of thinking skills would provide a naturally selective advantage over evolutionary time

• What kind of adaptations would have been most useful in the past

• Schemas - Facilitates gleaning info from experience, & organising that information

- Highly flexible

- Specialises in selecting info to help us adapt

• Social exchange - A distinctive adaptation shown by human hunter gatherers

• 2 NB social exchange schemas - Detecting cheating & making inferences regarding cost-benefit relationships

Syllogistic reasoning: Categorical syllogisms

• Syllogisms = Deductive arguments that draw conclusions from 2 premises

= A major premise + a minor premise + a conclusion

What are categorical syllogisms

• The premise state something about the category membership of the terms

• Each term represent all, none or some of the members of a category

• 1st & 2nd terms of the premise are linked through the categorical membership of the terms

• To determine if the conclusion follows logically from the premises

- Category membership of the terms must be determined

• Circle diagrams can be used to illustrate class membership

eg: All psychologists are pianists (Psychologists = the subject)

All pianists are athletes (Pianists = Middle term)

therefore all psychologists are athletes (Athletes = predicate)

• 4 kinds of premises:

Universal affirmatives (all X are…)

Universal negative statements (no X are…)

Particular affirmative statements (Some X are…)

Particular negative statements (Some X are not)

• No logically valid conclusions can be drawn from - 2 Particular premises

- 2 negative premises

• people have more difficulty with particular premises & negative premises

How do people solve syllogisms?

• Atmosphere bias - An early theory, does not account well for large number of responses

- If there is at least one negative, people prefer a negative solution

- It there is at least one particular premise, people prefer a particular solution

(if one of the premises has the word “no”, people prefer a solution with the word “no”

• Conversion of premises - People tend to think If A then B, into If B then A

• Widely accepted theory - People solve syllogisms by using a semantic process based on mental models

- (Meaning based models as opposed to rule based/syntactic processes)

• Mental model - Internal representation of information

- Some are more likely to lead to valid conclusions than others

→ A person is more likely to reach a deductively valid conclusion by using more than one mental model

• Difficulty in problems of deductive reasoning - Relates to number of mental models needed to represent premises

- To infer accurate conclusions from multiple mental models place great demand on working memory

→ THUS working memory capacity may underlie some of the errors in human reasoning.

• Experiments studying role of working memory:

~ Syllogisms presented orally and visually, orally places more demands on working memory

→ People were more successful at solving the visual ones

~ Syllogisms had to be solved while doing another task that used working memory or not

→ People fared better when the other task did not use working memory

• People solve logical problems more easily if the terms have high imagery value

Aids and obstacles to deductive reasoning

Heuristics in deductive reasoning

• Overextension errors - We overextend the use of strategies that work in some syllogisms to ones in which they don’t

eg: reversals work well with universal negatives, but not with other kinds of premises

• Foreclosure effects - Fail to consider all the possibilities before reaching a conclusion

• Premise-phrasing effects - Sequence of terms, use of particular qualifiers or negative phrasing influences reasoning

- Can cause us to leap to a conclusion without properly considering deductive validity

Biases in deductive reasoning

• Generally relate to the content of the premises & the believability of the conclusion

• Confirmation bias - We try to confirm what we already believe

- If content & conclusion seem true, we believe in the validity of the conclusion even if the logic is flawed

- Can be dangerous

Enhancing deductive reasoning

• Try to avoid heuristics and biases

•Engage in practices that facilitate reasoning - Take enough time and consider more alternatives

• Training and practice enhances performance on reasoning tasks - Esp if training relates to pragmatic schemas

• Mood - Affects syllogistic reasoning

- Sad mood leads to paying more attention to details & better performance at syllogistic reasoning tasks

INDUCTIVE REASONING

What is inductive reasoning?

• Reasoning from specific facts to a general conclusion

• Can never reach a logically certain conclusion

• Conclusions can be used to predict probability of future instances

• Forms the basis of the empirical method - Often involves generating & testing hypotheses

• We use inductive reasoning to reject the null hypothesis in research

(& can never know for sure that we are correct in doing so)

• People use inductive reasoning because:

~ It helps them to make sense out of the variability of the environment

~ Reduces uncertainty by helping them predict events

Causal inferences

• How people make judgments about whether something causes something else

•We assume causation if we observe covariation over time

• Confirmation bias leads to seeing illusory correlations

• Correlation does not imply causation

• We often fail to recognise that a given phenomena has many causes

• Discounting error - Once we identify one suspected cause, we stop searching for alternative or contributing causes

• Self-fulfilling prophesy - When the confirmation bias causes us to behave in ways that result in confirmation of our bias

Categorical inferences

• To draw inferences - People use bottom-up(info from sensory experiences)

and top-down(info they already know) strategies

• Bottom-up - Observing various instances & consider the degree of variability across instances

- From the observations we abstract a prototype/induce a category

- Then focused sampling is used to add new instances to the category

(Focussing mostly on properties that provided useful distinctions in the past)

• Top-down strategies - Selectively searching for constancies within many variations

- Selectively combining existing concepts & categories

Reasoning by analogy

• The reasoner must induce from the 1st pair of items some relation(s), then apply that relation to a 2nd pair of items

• Reaction-time methodology - To see what amounts of time is spent on which processes of reasoning

- Most of the time spent in solving verbal analogies is spent in encoding the terms & responding

Only a small amount is spent on doing the reasoning operations

• Analogies are used in everyday life - To make predictions about our environment

- We connect our perceptions with our memories by means of analogies

- The analogies then activate concepts that are similar to the current input

- We can then make a prediction of what is likely in a given situation.

AN ALTERNATIVE VIEW OF REASONING

Dual-process theory - 2 complementary systems of reasoning:

• Associative system

- Mental operations based on observed similarities and temporal contiguities

(eg tendencies for things to occur close together in time)

- Speedy responses sensitive to patterns & general tendencies

- Detecting similarities between observed patterns and patterns in memory

- Pay more attention to salient features than defining features

- Inhibits selection of patterns that are a poor match to the observed pattern

~ Representativeness heuristic

~ Belief-bias effect - We agree more with syllogisms that confirm our beliefs, regardless of their validity

~ False consensus effect - People believe their own values are more common than they are

• Rule-based system

- Manipulations based on the relations among symbols

- Requires more deliberate procedures

- Careful analyses of defining features based on rules

- Rigid constraints that rule our possibilities that violate the rules

- Evidence for rule-based reasoning:

~ We can recognise logical arguments

~ We recognise the need to make categorizations based on defining features

~ We can rule out impossibilities

~ We can recognize many improbabilities

CHAPTER 12 - PROBLEM SOLVING AND CREATIVITY

THE PROBLEM-SOLVING CYCLE

1. Problem identification

2. Problem definition & representation

3. Strategy formulation - Analysis, synthesis, divergent thinking & convergent thinking

4. Organisation of information

5. Resource allocation

6. Monitoring

7. Evaluation

• Flexibility NB in following the various steps of the cycle.

• Ability to regulate emotional state - related to better problem-solving

TYPES OF PROBLEMS

Well-structured problems

• Well-defined problems - Clear paths to solutions esp application of a formula

• 3 main errors when trying to solve well-structured problems:

1. Inadvertently moving backward - Reverting to a state that is further from the goal

2. Making illegal moves

3. Not realising the nature of the next legal move.

• Problem space - All possible actions that can be applied to solve a problem, given the constraints

• Algorithms - Sequences of operations in problem space that may be repeated & that guarantee a solution

- Generally continues until it satisfies a condition

• Limits of working memory - Limits us to considering only a few possible operations at a time

• Must use mental shortcuts - Heuristics (Informal, intuitive, speculative strategies that sometimes lead to a solution)

• Some problem solving heuristics:

Means-end analysis - Continually comparing the current state with the goal state,

& taking steps to minimise the difference between the 2 states

Working forward - Start at the beginning & try to solve the problem from start to finish

Working backward - Start at the end & try to work the way backwards from there

Generate and test - Simply generate alternative courses of action, not necessarily in a systematic way

Then check in turn whether each will work

Isomorphic problems

• Their formal structure is the same, only content differs

• It is often difficult to detect the underlying structural isomorphism of problems

→ Difficult to apply problem-solving strategies from one problem to another

- Esp when two problems are similar but not identical

Problem representation does matter!

• Tower of Hanoi - Some forms of the game took 16 times longer to solve, depending on representation

- Prefrontal cortex, bilateral parietal cortex & bilateral premotor cortex

• There is a relationship between working memory capacity & analytic problem solving ability

→ Mental processing speed showed no correlation with success

Ill-structured problems

• No clear path to a solution

• No well-defined problem spaces

• Difficult to construct appropriate mental representations for modelling the problems

• Much of the difficulty - Constructing a sequence of steps that inch ever closer to the solution

• Domain knowledge & justification skills - Both NB in solving both kinds of problems

• Insight problems - Because you need to see the problem in a novel way

- Must restructure your representation of the problem to solve it

• Insight - Distinctive and sudden understanding of a problem/strategy

- Often involves reconceptualising the problem in a totally new way

- Novel view of the problem or its solution

- Feel sudden, but are the result of much prior thought & work

- Esp utilized for ill-structured problems

Early Gestaltist views

• Emphasised - The whole is more than a collection of parts

• Insight - Requires people to perceive the problem as a whole

- A special process involving thinking different from normal, linear info processing

• Productive thinking - Insights that go beyond the bounds of existing associations

- Breaking away from existing associations to see the problem in a new light

- Can also be used for well-structured problems

• Reproductive thinking - Based on existing associations involving what is already known

The Neo-Gestaltist view

• 2 distinctions between insightful & non-insightful problem solving:

~ Normal problems - Solvers accurately predict success

Insight problems - Solvers show poor ability to predict success

~ Normal problems - Solvers felt “warmer”/closer to the answer as they progressed

Insight problems - Solvers felt far from reaching an answer until just before solving the problem

Insights into insight

• Insights - Can occur gradually (not an “a-ha” moment)

- an be right or wrong

• Sleep - Increases likelihood of insights

- (In both mathematical problems and ones that require understanding of underlying rules)

Neuroscience and insight

• Some brain activity networks - Active at rest and while problem solving

• During insight - Activity in right anterior super-temporal gyrus

- EEG records burst of high-frequency activity

- Activity in right hemisphere even before insight becomes conscious

- Right hippocampus NB (Integral to formation of new memories)

- Activity spike in right anterior temporal area just before insight is formed

• Even before seeing the problem - People who produced insight showed activation of frontal lobes

- People who didn’t produce insight showed activation of occipital lobes

→ Some solvers are more likely to use insight, and insight involves some advance planning

OBSTACLES & AIDS TO PROBLEM SOLVING

Mental sets, entrenchment and fixation

• Mental set - Can hinder problem solving

- “entrenchment”

- Frame of mind involving an existing model for solving a problem

- Fixate on a strategy that usually works well, but not in that particular instance

- Can also influence solving of routine problems

- Water jar problems (p503)

• Functional fixedness - Inability to see that something known for one use can be used in another way

- Prevents us from solving new problems by using old tools in novel ways

• Stereotypes - Another type of mental set

- Belief that members of a social group uniformly have particular characteristics

- Stereotype awareness arise between age 6 & 10

- Overgeneralise from an instance

Negative and positive transfer

• Transfer - Carryover of knowledge/skills from one problem situation to another

• Negative transfer - Solving an earlier problem makes it more difficult to solve a later one

• Positive transfer - The solution of an earlier problem makes it easier to solve a later one

Transfer of analogies

• When the solution to one problem is analogous to the solution of another.

Positive transfer was weaker when participants figured out the 1st solution for themselves

Usefulness of the analog depends on the induced mental set with which the solver approached problems.

• When contexts of 2 problems are similar - Participants more likely to apply the analogy

• People have trouble noticing analogies unless they are specifically told to look for them.

→ Positive transfer from solved to unsolved problems was more likely when pple tried to understand why a

solution worked, & not just how it worked.

Intentional transfer: Searching for analogies

• To find analogies - One must perceive relationships

• Actual content - irrelevant

NB - How closely their systems of relationships match

• Transparency - When people see analogies where they do not exist because of similarity of content.

- May lead to negative transfer between non-isomorphic problems.

Incubation

• Putting the problem aside for a while

• Minimises negative transfer

• Taking a pause from the stages of problem solving

• Incubation is more fruitful after more preparation

• Cognitively demanding tasks during incubation is detrimental to the incubation effect

• Incubation effect - more beneficial for divergent-thinking tasks

Neuroscience and planning during problem solving

• Planning - Saves time & improves performance

• Frontal lobes, esp pre-frontal cortex - NB in planning for complex problem solving tasks

Intelligence and complex problem solving

• Cognitive approach - Take the kinds of tasks used in IQ tests & isolate components of intelligence

• Components = Mental processes used in performing tasks

(eg translating conceptual representation into motor output)

• More intelligent participants - Spend more time on global planning (encoding and formulating a strategy)

& less on local planning (Forming & implementing strategies for the details of the task)

- Increased likelihood that the overall strategy will be correct

EXPERTISE: KNOWLEDGE AND PROBLEM SOLVING

• Expertise = Superior skills/achievement, reflecting a well-developed & well-organised knowledge base.

Organisation of knowledge

• Knowledge - Interacts with understanding in problem solving

• Beer test - Experts & novices could all sort beers according to taste (no difference in perception)

- Experts fared better in subsequent recognition tasks (better memory)

→ Experts have a superior framework for encoding and retrieving domain-related info

• Kids who knew a lot about biology fared better after reading low-quality texts

perhaps because the low quality forced them to pay attention. (Attentional influence)

Kids with little knowledge fared better after reading coherent texts

Elaboration of knowledge

• What differentiates experts from novices

Schemas of experts - Involve large, highly interconnected units of knowledge

- Organised according to underlying structural similarities among knowledge units

Schemas of novices - Small, disconnected units of knowledge, organised according to superficial similarities

How they classify problems

How they describe the essential nature of problems

How they determine and describe solutions

• People can remember things better, and solve problems better with what they remember, if they have a solid knowledge base with which to work.

Reflections on problem solving

• Verbal protocols - Statements made by problem solvers as they are solving a problem

- Can lead to increased problem-solving ability

• Communicating problem-solving strategies improves performance for novices

• Experts - Spend more time determining how to represent a problem, and less in implementing the strategy

→ Spend more time in matching the problem with their existing schemas

• Novices - Work backward from the unknown, needed information to the information they have

- Means-ends analysis

- Consider more possible strategies than experts do

• Experts - Only use means-ends analysis as a back-up

- Have more knowledge and better-organised knowledge & use their knowledge more effectively

- More accurately predict the difficulty of solving a problem

- Monitor their problem-solving strategies more carefully.

Automatic expert processes

• Experts - Automatize various operations through practice

- Can retrieve and execute these operations easily while working forward

• Schematization - Developing rich, highly organised schemas

Automatization - Consolidating sequences of steps into unified routines that require little or no conscious control

→ This shifts problemsolving from working memory (limited capacity) to long-term memory (infinite capacity)

Freeing working memory - Enables them to better monitor progress

BUT Automatization = reduced flexibility, esp when tackling problems structurally different from the norm.

Innate talent and acquired skill : See p518 for table of expert characteristics

• Practice - Should be deliberate/focussed

- Should enhance acquisition of new skills (not merely repetition)

• Interaction between innate abilities modified by experience - Explains differences between experts

• Prediction skills - Account for expert performance in some domains

(Expert typists & musicians look further ahead, tennis players predict trajectory of ball)

• Experts - use a more systematic approach to problems in their domain

Artificial intelligence and expertise

Can a computer be intelligent?

• Artificial intelligence (AI) - Intelligence in symbol-processing systems

• Computers - Cannot think

- Must be programmed to simulate cognitive processes (…?)

The Turing test

• 1st serious attempt to deal with issue of whether a program can be intelligent

• Turing test - Can an observer distinguish the performance of a computer from that of a human

- Computer, human respondent & interrogator

- Interrogator has conversation with human & computer, & has to say which is which

• Patterns of reaction time is more NB than reaction time itself

• Brute force programs - Evaluate all moves without respect to their quality

Expert systems

• Programs that can perform the way an expert does in a specific domain

• Not intended to simulate human intelligence, but to simulate performance in one domain

• Based on rules, followed and worked down like a decision tree

• Used to - Diagnose illnesses, processing of small mortgages, Microsoft trouble shooter

CREATIVITY : The process of producing something that is both original and worthwhile

What are the characteristics of creative people?

• Divergent production - Generation of a diverse assortment of appropriate responses

Torrance test of Creative Thinking

~ Measures diversity, quantity and appropriateness of responses to open-ended questions

Eg think of all the ways to use a paper clip

~ Also assesses creative figural responses

Eg how many ways to complete a drawing out of random squiggles

• Creativity as a cognitive process - Studies problem solving and insight

~ Some believe expertise and commitment distinguishes creative people

~ Becoming expert in their fields allows them to diverge from what they know to create something new

• Motivation plays a role in creative productivity:

~ Intrinsic motivation - Internal to the individual

- Essential to creativity

~ Extrinsic motivation - External rewards

- May impede creativity, but doesn’t always

(experiment - Extrinsic rewards for novel performance → Increased creativity and intrinsic motivation

- Extrinsic rewards for normal performance → Decreased creativity & intrinsic motivation)

• Personality - Flexible beliefs & broadly accepting attitudes

- More open to new experiences

- Self-confident & self-accepting

- Impulsive, ambitious, driven, dominant & hostile

• Evolutionary thinking - Creative ideas evolve much as organisms do

- Creativity = The outcome of a process of blind variation and selective retention

• Creative individuals

~ Moderately supportive, but strict and chilly early family lives

~ Highly supportive mentors

~ Early interest in chosen field

~ Early interest in exploring uncharted territory

~ First revolutionary breakthrough only after a decade practicing their craft

~ Some emotional support at time of breakthrough, then dedicate all energy tot heir work

(often neglecting family)

~ Often a 2nd breakthrough a decade after the 1st

Usually more comprehensive & integrative, and less revolutionary than the 1st

~ Poets & scientists less likely to continue making significant contributions than musicians & painters

• Investment theory of creativity

~ An alternative integrative theory

~ Multiple environmental & individual factors must converge for creativity to occur

~ Creative people takes a buy-low sell-high approach to ideas

Buying low = Seeing potential in ideas others consider worthless

Then builds the ideas until others can see the worth

Neuroscience and creativity

• Regions NB for creativity:

~ Prefrontal regions active during creative process

~ Brodman’s area (BA) 39

• Selective thinning of some areas seems to correlate with intelligence and creativity:

~ Left frontal lobe, lingual, cuneus, angular, inferior parietal, fusiform gyri

• Relative thickness of right posterior cingulate gyrus & right angular gyrus related to creativity

• Thinning & thickening of areas probably influence information flow within the brain

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