Chapter 5- Sensation



Chapter 5- Sensation

Day 1

Sensation vs. Perception

λSensation: a process by which our sensory receptors and nervous system receive and represent stimulus energy

λSensation is the raw data our brain takes in from the environment.

λPerception: a process of organizing and interpreting sensory information, enabling us to recognize meaningful objects and events.

λPerception “makes sense” of sensation.

λExample: Prosopagnosia

Bottom Up vs. Top Down Processing

λBottom Up Processing: analysis that begins with the sense receptors and works up to the brain’s integration of sensory information.

λ

λTop Down Processing: Information processing guided by higher-level mental processes

λAs when we construct perceptions drawing on our experience and expectations.

λ

Psychophysics

λPsychophysics: study of the relationship between physical characteristics of stimuli and our psychological experience of them

λLight-

λSound-

λPressure-

λTaste-

Sensation: Thresholds

λAbsolute Threshold:

λUsually defined as the stimulus needed for detection 50% of the time.

“Subliminal Messages”

λSubliminal: information that is below one’s awareness for conscious attention

λ

λDifference Threshold or (JND-Just Noticeable Difference): the minimum difference that a person can detect between two stimuli.

λWeber’s Law: to perceive a difference between two stimuli, they must differ by a constant proportion

λlight intensity-

λweight-

λtone frequency-

λSignal Detection Theory: predicts how and when we detect the presence of a faint stimulus (signal) amid background stimulation (noise)

λAssumes that there is no single absolute threshold

Sensory Adaptation

λSensory Adaptation: diminished sensitivity with constant stimulation.

The Science of Energy and Sensation

λTransduction-

λWavelength-

λHue-

λIntensity-

λbrightness

λloudness

Day 2

Sense 1- vision

Biology of Vision Step One: Light Enters the Eye

1. Light enters the eye through the _____________: (transparent protector) and the light passes through the _______________: (small opening/hole). The size of the opening (pupil) is regulated by the ____________: the colored portion of your eye that is a muscular tissue which widens or constricts the pupil causing either more or less light to get in.

Biology of Vision Step Two: An Image is Produced

2. Behind the pupil, the ___________, a transparent structure, changes its curvature in a process called _________________, and focuses the light rays into an image on the light-sensitive back surface called the __________: where image is focuses.

Biology of Vision Step Three: Chemical Reactions and Sight

3. Image coming through activates photoreceptors in the retina called __________________. As rods and cones set off chemical reactions they form a synapse with _________________ which forms a synapse with ______________ which fire action potentials along the _______________: that carries this information to be processed by the ________________: (sensory switchboard) that sends information to the ___________________ which resides in the ___________________. The brain then constructs what you are seeing and turns image right side up.

Parts of Retina

λBlind Spot: part of retina where optic nerve leaves the eye…no receptor cells are there.

λFovea: central focal point of the retina, where cones cluster.

λCones: located near center of retina (fovea)

λfine detail and color vision

λRods: located near peripheral retina

λdetect black, white and gray

Errors In Vision

λAcuity:

λNearsightedness:

λnearby objects seen more clearly

λFarsightedness:

λfaraway objects seen more clearly

Visual Involves Parallel Processing

λParallel vs. Serial: parallel means simultaneous while serial means step by step. Our brains process are often parallel processes while computers work serially.

λParallel Processing: simultaneous processing of several dimensions through multiple pathways. Different part of brain for:

Parallel Processing

λFeature Detectors: neurons in the visual cortex respond to specific features

Visual Information Processing

λTrichromatic (three color) Theory

λYoung and Helmholtz

λthree different retinal color receptors

Color Deficient Syndrome

People who suffer red-green blindness have trouble perceiving the number within the design

Opponent-Process Theory- opposing retinal processes enable color vision.

Color Constancy

λHuman Beings maintain Color Constancy: perceiving familiar objects as having consistent color, even if lighting changes to alter the wavelength given off by the object.

Context Affects Color

λWe only retain color constancy when the context remains the same.

λSame color will look different when compared in different contexts.

Day 3

Sense 2: Hearing (Audition)

λThe loudness of a sound is determined by a waves amplitude (height.)

λThe frequency, number of complete wavelengths that pass a point in a given time, determines the sounds pitch:

Hearing Threshold

Hearing is measured in decibels.

Parts of the Ear

λOuter Ear:

λJob:

λParts: auditory canal and eardrum.

λMiddle Ear

λJob:

λParts: Ossicles, made up of three tiny bones: hammer, anvil, and stirrup (malleus, incus, and stapes)

λInner Ear

λJob:

λParts: Oval Window, Cochlea, Basilar Membrane, Hair Cells.

Process of Hearing

1.Your ______________________________________________________________.

2.Your _________________________ with sound waves

3.This causes _________________________________ (the hammer, anvil and the stirrup) ____________________________________________________

4. ______________________________________________________________. The cochlea is fluid filled and _____________________________.

5. Inside the cochlea is a ____________________________________________ and are transduced into a _____________________________

6. Hair cells synapse with _______________________________________________

7. The auditory nerve transmits sound messages though your ____________________

____________________________________________________________________

Inner Ear and Vestibular Sense

λThe semicircular canals are connected to the cochlea by the vestibular sacs.

λThe semicircular canals contain substance that move when our head rotates or tilts and allows us to maintain our vestibular sense.

How Do We Perceive Pitch: 2 Theories

λHemholtz’s Place Theory: argues we hear different pitches because different sound waves trigger activity at different places in the cochlea’s membrane

λFrequency Theory: We sense pitch by the basilar membrane in cochlea vibrating at the same rate as the sound. Explains low pitch well….

λVolley Principle-

Parallel Processing

λJust like with vision, audition involves parallel processing

Hearing Loss

λConductive Hearing Loss: hearing loss caused by damage to the mechanical system that conducts sound waves to the cochlea like eardrum and ossicles.

λ Sensorineural Hearing Loss: damage caused to cochlea’s receptor cells (hair cells) or auditory nerves.

Day 4

Sense 3-Touch

λPremature Babies

λMonkeys

λ Skin sensations are a variation of the basic 4

λPain Is a Good Thing!

λGate Control Theory:

λ

Social Influence On Pain

-Pain is both a physiological and a psychological phenomenon.

-Depending on symptoms, doctors may use drugs, surgery, etc. or relaxation training, thought distraction.

Example:

Memories of Pain

λMore to our memories of pain than the pain we experienced.

λPeople tend to overlook duration of pain and instead concentrate on its peak moments and how much pain they felt at the end.

Sense 4-Taste

λ4 Basic Sensations

λSweet

λSour

λSalty

λBitter

Taste and Smell

λTaste and Smell are both chemical senses.

λTongue is central muscle for taste which contain taste buds.

λSmell runs through receptor cells in nasal cavity which are send neural signals to the olfactory bulbs in the brain.

Sense 5-Smell

λ5 million receptor cells at the top of your nasal cavity

λDetect 10,000 odors

λDecreases with age

λ Nasal Cavity brings the smell up to your receptors

λReceptor cells send the message to the brain’s olfactory bulb,then to the temporal lobe’s primary smell cortex

Smell and Emotion

λSense of smell activates areas in limbic system involved in emotion and memory.

λSmells can often evoke memories of the past or emotional experiences more often than most other senses.

Sensory Restriction

λPeople born without access to a sense, compensate with development of stronger other senses.

λSensory Restriction has produced mixed results depending on context:

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