Historical Foundations of Cognitive Psychology

[Pages:6]Historical Foundations of Cognitive Psychology

? Tim Curran ? tcurran@colorado.edu ? Lecture slides are available at:



* BUT YOU SHOULD STILL TAKE NOTES!

? Read Chapter 1 in Text

Cognitive Psychology

? A Definition

? The scientific study of mental processes such as perceiving, remembering, using language, reasoning, and solving problems.

? The formal discipline of "Cognitive Psychology" started in the mid-1900's.

? It's roots can be traced back much further.

Greek Philosophers ) (4th-5th Century BC

? Influential figures: Plato & Aristotle ? Began to consider questions about perception, memory,

and thought.

? Plato = Rationalist

? Emphasized logical analysis.

? Aristotle = Empiricist

? Emphasized observations of the external world.

? Specific assumptions, allowing for tractable questions:

? The world can be understood and predicted. ? Humans are part of that world. ? Explanations should be of this world.

Later Philosophy

(1600s - 1800's)

? Nativism (since Plato)

? Knowledge is innate ? heredity, nature

? Empiricism

? Influential figures: Hobbes & Locke ? Knowledge is gained through experience

? learning, nurture ? Associationism

? Knowledge originates from interconnected information.

? BANNANA-YELLOW-FRUIT-PEEL-LONG

? Key principle of modern "neural network" models.

? Compromise Positions

? Influential figures: Descartes & Kant ? Both Nurture and Nature are important.

Influence of Philosophy on Cognitive Psychology

? Contribution to Cognitive Psychology

? Identified many fundamental questions and assumptions about the nature of the mind.

? Limitations

? Lacked scientific methods.

Early Scientific Psychology

? Structuralism ? Functionalism ? Behaviorism

German Physicists

(1800s) ? Influential figures:

? Helmholtz: Color vision ? Fechner: Psychophysics

? Relationship between physical changes in stimuli and sensory experience.

? Applied scientific methods. ? Contribution to Cognitive Psychology

? Use of scientific/experimental methods.

? Limitation

? Limited to the study of simple sensory processes.

Structuralism

? Influential figure: Wilhelm Wundt ? Focus on identifying the basic building blocks

of conscious experience.

? Analogy with periodic table of elements in chemistry.

? Main method: "Introspection" under controlled conditions.

? Contribution to Cognitive Psychology

? Emphasized systematic, controlled observation. ? Importance of the understanding the structure of the

mind, and higher cognitive processes.

? Limitation

? Reliance on introspection.

Functionalism

? Influential figure: William James ? Mental processes must be adaptive, so what are

they good for?

? e.g., practical uses and functions ? Inspired by evolutionary theory.

? Main methods:

? Introspection, questionnaires, mental tests, animal experiments

? Contribution to Cognitive Psychology

? Emphasis on the functions and applications.

? Limitation

? Methods not very rigorous.

Limitations of Behaviorism

? Failures to account for aspects of human behavior

? Over-emphasis on animal experimentation ? Language

? Skinner suggested language was learned through basic principles of operant conditioning.

? i.e., we learn to say what is rewarded

? Fails to account for Generativity of language.

? The creation of novel utterances that have never been rewarded in the past.

? e.g., Chomsky (linguist)

Behaviorism

? Influential figures: John B. Watson, B. F. Skinner ? Guiding Principles:

? Only focus on that which is observable. ? Explain behavior; not thought, consciousness, etc. ? Theories should be simple. ? Break down behavior into irreducible constructs.

? Main method: Rigorous experimentation ? Contribution to Cognitive Psychology

? Emphasis on rigorous experimentation.

? Powerful theories of learning

? Classical Conditioning

? Learning relationships among stimuli. ? e.g., Pavlov's dog learned relationship between bell and food.

? Operant Conditioning

? Learning responses that are rewarded. ? e.g., A dog learns to sit for a treat.

? Failure to consider intervening mental processes

? Behaviorism:

Stimuli

Responses

? Cognitive Psychology

Stimuli

Mental Processes

Responses

? Stimulus (memorize this list)

? lion, onion, Bill, firefighter, carrot, zebra, John, clerk, Tim, nurse, cow

? Response (recall)

? lion, zebra, cow, onion, carrot, firefighter, clerk , nurse, John, Bill, Tim

? Mental Processes

? Strategies, grouping, reorganization, etc.

Overview of Different Approaches

Stimuli

Mental Processes

Responses

?Philosophy

?Argue about mental processes

?Introspection

?Directly tap into mental processes

?Behaviorism

?Study stimulus-response relationships ?Ignore mental processes

?Cognitive Psychology

?Study stimulus-response relationships ?Make inferences about mental processes

Information Processing

? The dominant approach toward studying human cognition.

? Decomposing a cognitive task into a set of abstract information processing steps.

? Designing experiments to understand the characteristics of each stage.

Outside Influences in mid 1990's

? Interest in optimizing human performance

? World War II

? Computer Science

? Artificial Intelligence ? Computer Metaphor

? Information processing, memory buffers, etc.

Information Processing Analysis Example

Representations & Processes

? A representation is a symbol for an entity in the real world.

? e.g., computers represent numbers in a binary code ? "8" = "0-1-1"

? A process manipulates/transforms representations in some way.

? e.g., addition, multiplication, etc

Sternberg's Memory Scanning Task



Information Processing Stages in the Memory Scanning Task

Encode

Search Memory

Decide

Respond

L

AKLM

L

Yes = /

?

No = z

AKLM

(stages during probe recognition phase)

Possible Search Processes

1. Serial, Exhaustive Search

? Whole letter set is always searched, one by one.

? RT increases with set size, and Yes = No

Possible Search Processes

2. Serial, Self-terminating Search

? Letters searched one by one until target is found or search is complete.

? RT increases with set size, but faster for "yes" responses because search stops when the target is found in the set.

Possible Search Processes

3. Parallel Search

? All letters in set simultaneously identified.

? RT unaffected by set size or yes/no.

Encode

Search

Decide

Respond

Sternberg's Results

? Serial Exhaustive Search

? Search rate inferred from slope = 38 ms per item

? Encoding/Decision/Response Stages

? Combined speed is y-intercept = 397 ms

? Don't vary with set size

? Vary with variables that should affect these processes.

Summary of Information

Processing Approach

? Decomposing a cognitive task into a set of abstract information processing stages.

? Attempts to understand processes/representations within each stage.

? A given stage (e.g., memory search) can be studied by manipulating variables (e.g., set size) hypothesized to affect that stage, and observing performance (e.g., reaction time).

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