psych 318 - exam 2 perception

lecture 12 + 13

challenges of studying infant perception

cant tell us what they see

can look more or less at things

researchers must infer what they are perceiving

perception “game”

researcher tries to make case for certain infant competence by demonstrating a pattern of looking time preferences

must eliminate alternative explanations for the patterns they observe

high vs low level interpretation

high level - preferences based on adult like concepts and features (people, objects, depth, gaze-direction)

low level - infants prefer symmetry (based on simple features symmetry, contrast, density)

gaze study farroni mnon and johnson

tests if infants prefer faces that are looking at them

• looking at vs away - prefer at

• maybe its symmetry - upside down images - no preference

• maybe its simple face template - side eye images - no preferences

result: infants dont have general understanding of gaze but prefer faces that match the simple head on face template

looking time studies involve

constant series of attempts to distinguish between low level interpretations and high level interpretations

methods for studying infant abilities

looking time preference

habituation/familiarization + preference

violation of expectation

preference studies

• implies discrimination

• lack of prefrence implies nothing

• must consider all possible reasons and rule out alternatives

• cant assume infants see same as we do

• infants may not have same categories and interpretations

habituation/familiarization + preference studies

• show infants repeated presentations of stimulus until looking time drops then show new stimulus

• increased looking time implies discrimination of 2 stimuli (recovery from habituation)

• can be used to ask questions about infant categories

violation of expectation

• show infants events that violate their expectations

• if expectations are violated they will look longer

• you can learn what they expect

• contrasts looking times between possible and impossible events - want to make the events as similar as possible

vision from birth

infants respond to visual stimuli

infants explore the visual world

theoretical positions on perception

constructivism

ecological view

constructivism

jean piaget

• we start with simple sensations

• through association we learn sensations co-occur

• drawing on these associations we construct coherent interpretation of sensations

• perception involves inference and top-down processing

LEARN MEANING THROUGH ASSOCIATING DIFFERENT EXPERIANCES

ecological view

• retinal image is full of rich information

• information is enough to specify what we perceive about the world

• perceptual systems evolved to pick up the information

• direct perception

• bottom up processing

VISUAL SYSTEM IS CONSTUCTED TO BE PREPARED TO PERCEIVE WORLD

apple example in constructivist view

at first apple means nothing

then combine sight + tough + sound + taste and eventually sight elicits expectations based on past experiences

ecological view apple example

sight of apple - at first has basic understanding object is 3D may know distance, size, texture

with experiance learns more details - taste, distance, etc

is infant born prepared to interpret visual stimuli in a meaningful way

piaget - constructivist - no

gibson - ecological - yes

depth cues

binocular cues

static monocular cues

motion cues

binocular cues

binocular disparity, convergence

static monocular cues

interposition, linear perspective, relative size, texture gradient

kinetic / motion cues

motion parallax

things that move together belong together

motion parallax

as we move the image of objects closer to us moves faster than images of farther objects

stereoacuity

binocular cues

infants can detect small differences in images to 2 eyes as a cue to depth

begins around 4 moths

development of sensitivity to binocular cues

preference for displays including binocular disparity as a depth cue emerges suddenly around 4 months of age

interposition - static monocular cues

one eye blindfolded - infants reach to left square

high level interpretation - infants sensitive to interposition as a depth cue, saw left square as closer

development of sensitivity to static monocular cues

number of studies find sensitivity emerging around 5-7 months

development of sensitivity to kinetic cues

studies suggest motion cues may be earliest to be detected

looming

expansion as cue to approach

present pattern of expansion to infant - infant moves head back, makes arm movements, increases blinking rate

motion parallax studies

• showed infants 3d object and 2d image of it - infants preffered 3D - binocular disparity or motion parallax

• monocular presentation - still preffered 3d but not as much

conclusions:

• can distinguish 3d from 2d representations

• can use motion parallax to detect depth

impossible object study

4 months

infants look longer to impossible cube - discriminate 2d representation of 3d from 2d representations that doesnt depict depth

summary of visual perception depth

infants seem to begin with assumption that there is a 3d world - sensitive to looming and use motion parallax to detect differences in 2d and 3d

get better at using cues to depth over time

• binocular cues 4 mo

• static monocular cues 7 mo

object unity

perceiving different parts of object as one

object segregation

perceiving separate objects as distinct

possible sources of information for unity vs segregation

depth information

continuity, regular shape

shared features (color texture)

previous expereince

at what age can infants use continuity to unify partially occluded objects

7 months - looked longer at broken rod - more novel - they had perceived single rod

4 months - did not - not sensitive to continuity as a cue - do use continuity is motion was present

2 mo - not sensitive even with motion - prefer complete rod - preferred broken if occluder was narrower

what is an important cue to object boundaries early in development

motion

object properties to identify object unity

8 mo olds looked longer at move together event - concluded that they use features like color and continuity to segregate objects

4.5 mo looked equally - seemed to have no expectation - when given exposure to each object alone then they are suprised

should infants be able to perceive objects in a 3D worlds without experience (according to the 2 theorists)

constructivists no

ecological yes

fantz - do infants prefer faces over other stimuli

yes but not because of their organization as faces

driven instead by lower level properties of faces (high contrast, curvature)

fantz - tracking images with face features

tracked features with face like organization more than other images

differences decline at 4-6 weeks

conclusion of fantz face studies

from birth infants are biased to attend to faces

initial bias probably reflects subcortical mechanism

may not be the same as real understanding of faces

ultrasound light shining in face vs non face configuration

turned face way more towards face shape

turned face slightly less away from face shape

• preference for face like organization prior to visual experience - subcortically controlled - declines about 6 weeks after birth

newborns and moms face

appear to distinguish moms face in first few days - show preference over strangers

need all information can get - includes hairstyle

specialization of processing human faces pascalis dehann nelson

humans better at human than monkey discrimination - opposite true for monkeys

do we lose ability process non human faces pascalis dehann nelson

6 mo look longer at novel human and monkey faces

9 mo look more at novel human but not novel monkey faces

• between 6-9mo infants become less able to discriminate non-human faces

• specializing in human face processing with cost in ability to process non-human faces

do infants specialize in processing faces of own race kelly et al

show 1 face habituate - show same face in new orientation and a completley new face - if recognizes face should prefer novel face

3 mo - good at task regardless of race of face

6 mo - good at chinese and caucasian not african or middle eastern

9 mo - good only at caucasian

perceptual narrowing hypothesis

with increased experience with certain types of faces and a lack of contact with other types of faces perceptual narrowing takes place

• increased discrimination and recognition of familiar face types and decreased discrimination and recognition of less familiar face types

categorizing facial expressions - bronstein and arterberry

how well do 5mo recognize same expression on different faces and same face in different expression

• categorize smiling faces together as different from fear even when displayed by different faces

summary face perception newborns

• prefer low level features typically found in faces

• prefer face like configuration

• prefer faces that are gazing at them

• can recognize moms face

• prefer attractive faces

face perception 5 mo old summary

categorize facial expressions even on different faces

categorize individual faces

match facial expression of emotion to vocal expression

do earliest for moms face and voice and earlier for female than male faces/voices

summary face perception 6-9mo olds

specialize in processing faces like those they see most

lose ability to make discriminations in nonfamiliar faces

perceptual narrowing

modality

sensory channel carrying certain information - visual auditory tactile

amodal

not tied to a particular sense

• synchrony

• rate

invariant

not changing constant

amodal invariants in the ecological vies

abstract similarities or correspondences in the information coming in from different senses

important in detecting correspondences between senses and information about the world

intersensory integration

each sense provides unique information

perceiving world involves relating information form different senses

HOW WELL DO INFANTS RELATE INFORMATION FROM DIFFERENT SENSES

visual haptic meltzoff and borton pacifier study

infants preferred to look at pacifier they had sucked on

1mo olds have some ability to integrate visual and tactile information for shape

vision and audition integration in newborns

newborns turn their heads in direction of sound -

intersensory: they turn different amounts depending on location of sound

reflex: u shaped curve describes change over time

spelke can 3mo link visual and auditiory events by synchrony

• are they sensitive to correspondence between visual and auditory timing - infants look to film of bouncing animal that matched soundtrack - can use synchrony to match visual and auditory events

• are they able to match tempo when tracks are out of synchrony - look to film that matched tempo even when impact was out of synch with film

3mo can use synchrony and tempo to match visual and auditory events

sights and sound matchup 3 mo old vs older babies

3mo - look equally when sound occurred at bottom of trajectory or at top

older baby - sound corresponds to contacting surface

sound sight refinement - balls tube rotates - bahrick

4 mo olds - prefer displau that are synchronous but dont distingush single from multiple balls

6 mo olds - sensitive to one vs many differences

sensory integration summary

evidence for intersensory integration at birth - may be reflex or fragile at first

• vision and touch

• vision and audition

by 3 mo - good at matching visual and auditiory events, continue to refine ability over time

can newborns imitate - meltzoff moore

48hrs old tongue protrusion, mouth opening, lip protrusion, finger waving

• strongest results for tongue protrusion and mouth opening

• newborn chimps imitate the same expressions

controversion over neonatal imitation

• what does it mean

  • subcortical mechnism (reflex?)

  • sign of sophisticated knowledge

• does it really exist at all o

oostenbroek et al longitudnal study for imitation

best conclusion for tongue protrusion imitation

evidence isnt that good

doesnt occur more to matching model than control consistently across ages

no good evidence for neonatal imitation

what information can newborns relate (from different senses)

vision and touch

vision and sound

vision and motor movements