sensations vs. perceptions

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Chapter 5Chapter 5

PERCEPTIONPERCEPTION

Sensations vs. PerceptionsSensations vs. Perceptions

Perception Our interpretations of the real world

How do Sensations Become Perceptions A perception begins with some stimulus

which activates sense receptors Once activated, a sense organ transforms

energy into electrical signals or impulsesthat travel to the brain

Sensations vs. Perceptions (continued)Sensations vs. Perceptions (continued)

Parts of the Brain transform electrical signalsinto basic sensationsSensations are your first experiences ofoutside stimuli They consist of meaningless bits of sensory

information

Each of us has a unique set of experiencesthat may automatically add meanings,feelings, or memories to our perceptions

Sensations vs. Perceptions (continued)Sensations vs. Perceptions (continued)

The brain automatically assemblesmany thousands of individual sensationsinto a meaningful pattern or imagewhich is called perception Personalized interpretations rather than

true copies of things in the real world

Enduring Issues in PerceptionEnduring Issues in Perception

Role of Learning Newborns’ senses are all functional and

some degree of perceptual ability isprobably innate

Enduring Issues in Perception (Enduring Issues in Perception (concon’’tt))

Parts vs. the Whole Feature Analysis

The theory that weperceive a form onthe basis of arelatively smallcollection of features,which can becombined, rotatedand expanded(Structuralism)

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Gestalt School Psychologists who

believe that ameaningful overallpattern (Gestalt) isperceived before itsparts are recognized

“The whole is morethan the sum of itsparts”


Perceptual Illusions Used to determine how people process

perceptual informationBottom-Up vs. Top-Down Processing Bottom-Up: sensory receptors to brain Top-Down: perceiver’s expectations &

context play a role from the beginning Perceptual Sets:

learned expectations that are based on ourpersonal social or cultural experiences. Theseexpectations change or bias what we see.

Functions of PerceptionFunctions of Perception

Where is it? – Location Attention

Automatic – distinguishing object frombackground

Deliberate – allocation of attention

Depth Perception Ability to experience depth in visual perception

(relative & absolute distances)

Functions of Perception:Functions of Perception:Depth Perception Depth Perception (continued)(continued)

Binocular Depth Cues – depend uponthe movement of both eyes Convergence – based on signals sent from

the muscles that turn the eyes Binocular (Retinal) Disparity – depends on

the distance between the eyes Stereopsis 3-D Glasses


Monocular Depth Cues Depend upon the signals sent from one

eye Determined by how objects are arranged in

the environment


Motion ParallaxRelative SizeConstancyLinear PerspectiveTexture GradientAerial PerspectiveOcclusion (Interposition)

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Functions of Perception (continued)Functions of Perception (continued)

Illusions of Depth Muller-Lyer, Ponzo, Ames Room, Vista

Paradox (pg. 146) If our perceptual cues are changed, our

otherwise reliable perceptual processes canbe deceived


Auditory Localization Differences in how and when a sound

reaches the two ears enable the brain tocompute the location of its source


Is it Moving? – Movement Motion Perception

We distinguish between changes inenvironment that are caused by movements inthe environment and changes that are causedby our own movements


Illusions of Motion Apparent Motion (Phi Phenomenon) Induced Motion (moon appears to move

through clouds) Motion Aftereffect (train stops and objects

outside appear to move backwards)


What is It? – Form Feature Analysis

Involves the recognition of features (lines,intersections & corners) as well as location,orientation, contrast, and fuzziness.

Features are grouped into clusters


Gestalt View (Principles) Figure-Ground Distinction

In organizing stimuli, we tend to automaticallydistinguish between a figure and a ground

The figure with more detail, stands out againstthe background, which has less detail

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Gestalt View (continued)Grouping Similarity Proximity Continuity Simplicity Closure

Subliminal PerceptionSubliminal Perception

Subliminal Messages Brief auditory or visual messages that are

presented below the absolute threshold, whichmeans that there is a <50% chance that they willbe perceived

Although subliminal messages may be ineffectivein changing behavior, there is evidence thatemotions may unknowingly or subliminallyinfluence perception

Cultural Diversity:Cultural Diversity:Changing PerceptionsChanging Perceptions

Besides affecting social and personalvalues, cultural influences can alsoaffect our perception of color depth,constancy, and motion

ESP: Extrasensory Perception

A group of psychic experiences thatinvolve perceiving or sendinginformation outside normal sensoryprocesses or channels Includes 4 general abilities

Telepathy Precognition Clairvoyance Psychokinesis

ESP: Extrasensory Perception (con’t)

Most academic psychologists do not yetaccept the existence of psychic powersor extrasensory perception, which arecollectively called psi phenomena Trickery Questionable methodology (unreliable

scientific procedures)

Application: Creating PerceptionsApplication: Creating Perceptions

Creating Reality Virtual Reality

A perceptual experience of being inside anobject, moving through an environment, orcarrying out some action – that is entirelysimulated by a computer

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Application: Creating PerceptionsApplication: Creating Perceptions(continued)(continued)

Creating Impressions Social psychologists have concluded that

facial features have a significant affect onour first impressions of people

First impressions are also influenced byracial stereotypes, both positive andnegative, based on physical features suchas skin and hair color

Life-Span Changes in PerceptionLife-Span Changes in Perception

Sensory World of Infant A newborn’s distance senses (sight &

hearing) are not as developed as the senseof touch, smell & taste

Sight is probably the least developed sense They have poor depth perception and are

unable to see the full color spectrum

By the age of 7 months, babies’ vision &hearing are acute

Life-Span Changes in PerceptionLife-Span Changes in Perception

The Aging Senses Sensory systems begin aging during the

40s and may become severe by the 70sand 80s

Life in a noisy environment may contributeto hearing loss

Medication may reduce taste sensitivity

sensations vs. perceptions

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