Perception Chapter 6Perception Chapter 6

Mr. McElhaneyMr. McElhaney

““Seeing”Seeing”

1.1. Gregory explains vision: Pay attention to the Gregory explains vision: Pay attention to the following:following:

2.2. Gestalt, Foreground, Background, SilhouetteGestalt, Foreground, Background, Silhouette

3.3. How does the eye select, filter and become How does the eye select, filter and become conscious or make sense of visual world?conscious or make sense of visual world?

4.4. How does the perceptual system work?How does the perceptual system work?

5.5. What is the role of experience in perception? What is the role of experience in perception?

6.6. What are illusions?What are illusions?

Questions to be answeredQuestions to be answered

What is the role of experience in What is the role of experience in perception?perception?

What is the role of culture ?What is the role of culture ? How does the mind make meaning of the How does the mind make meaning of the

stimuli from the environment?stimuli from the environment?

Perception Perception

Making sense of visual stimuliMaking sense of visual stimuli How we assemble sensations into How we assemble sensations into

meaningful patternsmeaningful patterns

Perception is empirical= experientialPerception is empirical= experiential

Constancies Constancies Perceptual ConstancyPerceptual Constancy

Perception needs experiencePerception needs experience Must be familiar with objects to use their size to judge Must be familiar with objects to use their size to judge

distancedistance Size ConstancySize Constancy

Perceived size of object remains the same even Perceived size of object remains the same even though size on the retina changesthough size on the retina changes

Shape ConstancyShape Constancy Shape of an object remains constantShape of an object remains constant Alcohol impairsAlcohol impairs

Brightness ConstancyBrightness Constancy Brightness of objects appear to be the same if Brightness of objects appear to be the same if

surrounding objects are illuminatedsurrounding objects are illuminated

Perceptual OrganizationPerceptual Organization

Contrasts help perceptionContrasts help perception Object and plain backgroundObject and plain background

Figure Figure GroundGround- perception is first- perception is first Reversible Reversible figure figure groundground

Perception is reversed Perception is reversed Background is more visibleBackground is more visible

GestaltGestalt Principles Principles

We have a tendency to complete shapes We have a tendency to complete shapes into whole unitsinto whole units

Factors of Perception that bring order to Factors of Perception that bring order to perceptions:perceptions:

Visual depictions can be designed to be Visual depictions can be designed to be perceptually efficient.perceptually efficient.

Gestalt PrinciplesGestalt Principles:: ““TheThe whole is greater than its parts.” whole is greater than its parts.”

Nearness-Nearness- items near are grouped together items near are grouped together items will be seen in groupsitems will be seen in groups

Similarity-Similarity- perceived size/shape color form tend perceived size/shape color form tend to be grouped togetherto be grouped together

Continuation- continuity-Continuation- continuity- tend toward simplicity- tend toward simplicity- it’s easier to visualize wavy line than complex it’s easier to visualize wavy line than complex rowsrows

Closures-Closures- tendency to complete a figure so that tendency to complete a figure so that it has an overall formit has an overall form

Common region-Common region- stimuli found in a common stimuli found in a common region or area seen as a groupregion or area seen as a group Used in everyday patternsUsed in everyday patterns

CamouflageCamouflage

Breaks up Breaks up foregroundforeground organizztion images organizztion images also known as also known as cryptic colorationcryptic coloration or or

concealing colorationconcealing coloration,, allows an allows an otherwise visible organism or object to otherwise visible organism or object to remain indiscernible from the surrounding remain indiscernible from the surrounding environment. environment.

© E.R. Degginger/Animals Animals

Perceptual HypothesisPerceptual Hypothesis

We find meaning and organize visual We find meaning and organize visual perceptions from a distanceperceptions from a distance

When we get closer the hypothesis is When we get closer the hypothesis is proved or disprovedproved or disproved

We expect and understand based on We expect and understand based on experienceexperience we have preexisting ideas we have preexisting ideas

Necker’s CubeNecker’s Cube

Ambiguous stimuliAmbiguous stimuli Patterns that allow Patterns that allow

more than one more than one interpretationinterpretation

Brain interprets Brain interprets patternspatterns

We We actively construct actively construct meaningfulmeaningful perceptions/ not perceptions/ not passivepassive

Problem- Problem- Conflicting Conflicting informationinformation prevents prevents stable perceptionstable perception

Depth PerceptionDepth Perception

Ability to perceive 3 dimensional spaceAbility to perceive 3 dimensional space Nativist= inborn abilityNativist= inborn ability OrOr Empiricists = experience based Empiricists = experience based Depth perception is bothDepth perception is both

Visual CliffVisual Cliff

The concept of testing depth perception in The concept of testing depth perception in babiesbabies

Can babies identify Can babies identify Depth CuesDepth Cues?? Features of the environmentFeatures of the environment and messages and messages

from the body that supply information about from the body that supply information about distance/depthdistance/depth

•Study found that Infants have some innate depth perception.

•Implications with both studies are that humans have both

Why do infants and babies fall off Why do infants and babies fall off beds and things?beds and things?

Depth perception and motor skills have not Depth perception and motor skills have not integrated yetintegrated yet

Depth Perception: Muscular CuesDepth Perception: Muscular Cues

Monocular or BinocularMonocular or Binocular Sensations Sensations from muscles attached to each from muscles attached to each

lens flow back to the brainlens flow back to the brain AccommodationAccommodation- (using muscles) - (using muscles) bending bending

of lensof lens to focus on nearby object to focus on nearby object ConvergenceConvergence= Distant vision = parallel = Distant vision = parallel

within 50’ eyes convergewithin 50’ eyes converge Controlled by muscles feed info to the brain Controlled by muscles feed info to the brain

helps helps judge distancejudge distance

Convergence

Muscular Cue:Muscular Cue: Stereoscopic Stereoscopic Vision=2 eyesVision=2 eyes

Focusing of image by two eyes = Focusing of image by two eyes = 3 3 dimensional sightdimensional sight

Retinal Disparity Retinal Disparity (Binocular cue)=(Binocular cue)= two eyes, two eyes, see the world differentlysee the world differently ““Discrepancy in images that reaches right and Discrepancy in images that reaches right and

left eye” (3 D movies pg 221)left eye” (3 D movies pg 221) Produces DepthProduces Depth

One eyed people can learn to perceive One eyed people can learn to perceive depthdepth

Pictorial Cues for DepthPictorial Cues for Depth

Linear PerspectiveLinear Perspective Relative sizeRelative size Height in picture planeHeight in picture plane Light and shadowLight and shadow Texture gradientTexture gradient OverlapOverlap Aerial perspectiveAerial perspective Relative MotionRelative Motion

Fig. 6.14 (a) Linear perspective. (b) Relative size. (c) Light and shadow. (d) Overlap. (e) Texture gradients. Drawings in the top row show fairly “pure” examples of each of the pictorial depth cues. In the bottom row, the pictorial depth cues are used to assemble a more realistic scene.

The The Moon IllusionMoon Illusion

Perceiving the moon as Perceiving the moon as larger when it is larger when it is low in low in the skythe sky;;

Problem: the moon is Problem: the moon is closer when the directly closer when the directly overheadoverhead

The brain thinks the low The brain thinks the low moo is larger because moo is larger because of Depth Cuesof Depth Cues

Horizon makes moon Horizon makes moon seem farther awayseem farther away

Perceptual LearningPerceptual Learning

Refers to experiences that cause changes Refers to experiences that cause changes in the brain that alter how we process infoin the brain that alter how we process info

We learn to focus on one part of stimuliWe learn to focus on one part of stimuli

We learn to tell the difference between We learn to tell the difference between stimulistimuli

Perceptual HabitsPerceptual Habits

Through ExperienceThrough Experience We establish habits of perceptionWe establish habits of perception Patterns of Patterns of organization and attentionorganization and attention

Perceptual Features-Perceptual Features- are learned and the are learned and the brain becomes sensitive to:brain becomes sensitive to:

Lines, shapes, edges, spots, and Lines, shapes, edges, spots, and colorscolors

Ames Room- appears square, distorts appears square, distorts proportions= Both proportions= Both Perceptual Habits and Perceptual Habits and Perceptual LearningPerceptual Learning

Perceptual Habits continuedPerceptual Habits continued

Other Race EffectOther Race Effect Inverted vision= human brain can adaptInverted vision= human brain can adapt

• Through active movementThrough active movement• People need to be active to adaptPeople need to be active to adapt

Examples of IllusionsExamples of Illusions

Illusions: Illusions: Size Distance VarianceSize Distance Variance The size of an The size of an

object’s image is object’s image is precisely related precisely related to its distance to its distance from the eyefrom the eye

Two objects make Two objects make images the same images the same sizesize

Perception cannot occur without Perception cannot occur without attentionattention

Motives for one stimulusMotives for one stimulus will make perception for will make perception for that stimulus more sensitivethat stimulus more sensitive

We are surrounded by stimuliWe are surrounded by stimuli

Selective Attention:Selective Attention: we give some messages we give some messages priority.priority.

Divide Attention:Divide Attention: Causes us to divide attention Causes us to divide attention among tasks that require more or less effortamong tasks that require more or less effort

Types of stimuli that impact Types of stimuli that impact attentionattention

Intense stimuliIntense stimuli commands attention commands attention (brighter, louder, larger- Advertising psych)(brighter, louder, larger- Advertising psych)

RepetitiousRepetitious Stimuli- grabs attention Stimuli- grabs attention

Contrast or changingContrast or changing stimuli gets attention stimuli gets attention

Other Factors to AttentionOther Factors to Attention

Intentional Blindness-Intentional Blindness- when focusing on a when focusing on a specific item we miss other info/itemsspecific item we miss other info/items

HabituationHabituation= boredom, we respond less to = boredom, we respond less to unchanging stimuli <to not be stimulated>unchanging stimuli <to not be stimulated> Connected to Connected to Adaptation-Adaptation- decrease the actual decrease the actual

number of sensory messages sent to brainnumber of sensory messages sent to brain

Biological Receptivity Biological Receptivity

Orientation Response: Orientation Response: prepares us to prepares us to receive informationreceive information Pupils enlargePupils enlarge Brain patterns shiftBrain patterns shift Breathing stopsBreathing stops Blood flows to head increasesBlood flows to head increases Physical turn toward stimulusPhysical turn toward stimulus ““Double Take”Double Take”

Perceptual ExpectanciesPerceptual Expectancies

Expecting stimuli in a certain mannerExpecting stimuli in a certain manner ““Past experiences, motives, context”Past experiences, motives, context” ““Prepares you to perceive in certain ways.”Prepares you to perceive in certain ways.”

““We see what we expect to see.”We see what we expect to see.” Can be created by suggestionCan be created by suggestion

Perceptual ExpectanciesPerceptual Expectancies

Bottom Up Processing-Bottom Up Processing- Feature analysis Feature analysis of info with sensory units build upward to a of info with sensory units build upward to a complete perceptioncomplete perception

Top Down Processing-Top Down Processing- pre-existing pre-existing knowledge used- to rapidly organize knowledge used- to rapidly organize features (small units) to a wholefeatures (small units) to a whole

Perceptual CategoriesPerceptual Categories

Experiences are sorted into categoriesExperiences are sorted into categories LabelsLabels impact the way we perceive others- impact the way we perceive others-

ClassesClasses TypesTypes GroupsGroups

Eyewitness TestimonyEyewitness Testimony

Is often incorrectIs often incorrect When a person is surprised, threatened, or When a person is surprised, threatened, or

under stress are under stress are especially prone to especially prone to distortiondistortion

Maslow and PerceptionMaslow and Perception

Found some people perceive themselves and Found some people perceive themselves and other with great accuracy.other with great accuracy.

Characteristics:Characteristics:• Lack Self ConsciousnessLack Self Consciousness• Not criticalNot critical• Not evaluatingNot evaluating

Problem of Problem of HabituationHabituation- boredom, responding - boredom, responding less to stimuliless to stimuli

Need to Dishabituate- reverse habituation = pay Need to Dishabituate- reverse habituation = pay attentionattention

Examples of:

Mother and infant

Child @ Christmas

Two people in love

How to Improve PerceptionHow to Improve Perception

Remember perceptions Remember perceptions are reconstructionsare reconstructions of of realityreality

Break perceptual habitsBreak perceptual habits and interrupt habituationand interrupt habituation

Shift adaptationShift adaptation levels levels and broaden frames of and broaden frames of reference by seeking out reference by seeking out of the ordinary of the ordinary experiencesexperiences

Beware of perceptual Beware of perceptual setssets

Be aware of the ways in Be aware of the ways in which motives and which motives and emotions influence emotions influence perceptionsperceptions

Make a habit of Make a habit of engaging engaging in reality testing.in reality testing.

Pay attentionPay attention