Week 5: Perceptual development Visit website! Midterm in two weeks!

Perceptual Development 3 Methods of determining infant perception Visual Preference – Developed by Fantz – Infant in chamber with peephole, what do they look at most?

Perceptual Development 4 Methods of determining infant perception Visual Preference Evoked potentials

Perceptual Development 4 Methods of determining infant perception Visual Preference Evoked potentials High Amplitude sucking Habituation/dishabituation

Senses of the Newborn SenseNewborn Capabilities Vision Least developed sense; accommodation and visual acuity limited; sensitive to brightness; discriminates some colours; tracks moving targets Hearing Turns to a sound; can differentiate loudness, direction, frequency; very responsive to speech; recognize mother’s voice Taste Prefers sweet; discriminates between sour, salty, bitter, sweet Smell Detects odours; turns away from unpleasant ones; Breast- fed babies can tell own mother’s breast and underarm odor Touch Responsive to touch, temperature change and pain

Senses continued Infants legally blind at birth – 20/600 at birth, by 12 months, down to 20/100 Auditory perception good – Esp speech perception Have likes and dislikes re. Food – Have sweet tooth like many of us Show aversion to unpleasant smells – Wrinkle their noses at bad smells Babies like to be touched – Massaged preemies grow faster

Pattern Perception (0-2 months) Prefer moderately complex stimuli over highly complex stimuli Like a lot of contrast, like black on white

Examples: Which will babies prefer?

This one, due to high contrast!

Pattern Perception (0-2 months) Prefer moderately complex stimuli over highly complex stimuli Like a lot of contrast, like black on white Show externality effect

Externality Effect Seen at 1 month!

Externality Effect now Obsolete! Gone at 2 months

Pattern Perception (0-2 months) Prefer moderately complex stimuli over highly complex stimuli Like a lot of contrast, like black on white Show externality effect Like curvy things, contours

Which will babies prefer?

This one!! It’s curvilinear

Pattern Perception (0-2 months) Prefer moderately complex stimuli over highly complex stimuli Like a lot of contrast, like black on white Show externality effect Like curvy things, contours Vertical symmetry

Which will babies prefer?

This one! It’s symmetrical!

Later Form Perception: 2 – 4 months Are scanning whole objects Start to show a preference for the human face

Face perception Babies seem to like to look at faces – Why? – Contrast – Curvy – Symmetrical

Take all features into account…

Face perception Babies seem to like to look at faces – Why? – Contrast – Curvy – Symmetrical Will track a face-like picture over something else

Guess which baby prefers?

Face perception Early on, spend more time looking at edges and contours than at middle of face By 3 months clearly prefer normal faces, and that of own mother, and that of “attractive” people By 7 months, can categorize and remember faces By 8-10 months, can interpret emotion in faces

Meaning of face preference Could be simply a result of stimulus preferences Could be social – Dannemiller & Stevens, 1988 – Data from eye gaze studies… We as adults have a “face processing area”

Intermodal Perception Enrichment vs differentiation theory – Senses separate; must integrate vs. senses integrated; must differentiate Former is probably correct – Bahrick’s research

Integrating modalities Babies need to achieve three tasks: – Attending At 5-7 months, sight and sound well integrated – Identifying Can integrate two sense to identify source or objects – Locating They can integrate visual and grabbing information to time a grasp properly

Infants’ spatial abilities Chapter 8

Babies’ 3D vision Have binocular vision, or stereopsis, by 3 months Can only use 2D pictorial cues at 7 months Show evidence of perceiving depth by 1 month, but do not interpret it until they are actively crawling

Visual Cliff Gibson and Walk’s animal study Crawling infants won’t cross to mom! If placed on visual cliff at 2 months, heart rate DEceleration, i.e. interest Richards & Rader (1981)

Interaction Babies who move understand principles of movement better Will search for objects that have changed location whether due to object’s movement, or to own movement Bai & Bertenthal (1992)

Other spatial/ pictorial cues Have depth perception Show size constancy to some extent, esp with motion between 1 and 3 months, but not fully until 6 months Can’t use linear perspective until 7 months See subjective contours at 3 months

Subjective Contours

Other spatial/ pictorial cues Have depth perception Show size constancy to some extent, esp with motion between 1 and 3 months, but not fully until 6 months See subjective contours at 3 months Appear to have mature understanding of objects

Spelke’s Rod and Frame test

Spelke’s Rod and Frame Test, cond’ Babies know that it is not 2 separate rods, but rather one whole!

Children’s Knowledge of Objects Baillargeon’s work: Babies seem to have knowledge about objects at a very young age Uses “Violation-of-Expectation” paradigm to infer 4 month old infants’ knowledge about occluders

Violation of Expectation: Habituation Event Screen moves through 180 degree plane until baby gets bored

Violation of Expectation: Test Event #1: Possible Event Screen moves through 112 degree plane and stops at occluder

Violation of Expectation: Test Event # 2: Impossible event Screen moves through 180 degree plane despite occluder

Violation of Expection: Results Babies “are surprised” by the impossible event Find the same thing with other object properties like containment and support Spelke’s research with the moving rod is the same idea

What does it mean? Babies may be born with principles of cohesion, continuity and contact Maybe not innate knowledge about objects per se, but innate constraints Possess tools to build cognition from birth: object concept present early on!

Later Form Perception: 6 months to 1 year By 7 months get linear perspective By 9 months can extract whole from a random dot pattern By 12 months, they watch a single point of light trace an object, then act like they’ve seen the whole object

Summary Infants are born with fairly strong capabilities Infant perception develops rapidly over the first year of life By 12 months, they can see well and are moving, and are largely able understand their environment!

How old is this woman?

What do you see here?

Ambiguous Figures Physiological perception is done early; cognitive perception develops later They can’t shift back and forth between pictures until they are years old!

Later Perceptual development, con’d Children also have trouble telling some letters apart: M W b d h

Spatial orientation Children before 3 have a hard time keeping track of their environment Tend to view things in a straight line Poor cognitive mapping

Spatial Cognition Herman, Shiraki, & Miller, 1985: – Examined 12 younger (3 – 4) and 12 older (4.5 – 5.5) nursery school children who had been at the same school for the same amount of time – Brought them to 3 locations and asked them to point out 5 landmarks – Older a bit better than younger, but still not great – Very young children have difficulty inferring spatial relationships, even in familiar environments

More Spatial Problems Field Dependence / Independence – Have trouble with this until they are 10 – Embedded Figures Task

Embedded Figure #1

Embedded Figure #2

More Spatial Problems Field Dependence / Independence – Have trouble with this until they are 10 – Embedded Figures Task – Role of Inhibition and Cognitive Flexibility, hard to separate figure and ground

Summary of Perception and Spatial Cognition In infancy, focus is on what infants can or cannot see, i.e. colours, patterns, depth, etc… How much is present at birth? How much develops? Once they see, they improve in how flexibly they see items They also improve in how they mentally represent the space around them