W4 L4 Perceptual development

incorrect assumption about infant’s perception by WIlliam James

‘blooming, buzzing confusion’

define visual acuity

sharpness of visual discrimination

how can visual acuity be measured

through preferential-looing method

how does vision develop in infants, what age does it approach adult level

sharpness of infants’ visual discrimination develops rapidly - approaches that of adults by age 8 months

when do infants’ visual acuity reach full adult acuity

6 years old

what visual preferences do very young infants (up to 2 months) have

naturally drawn to high contrasting patterns

contrast sensitivity

the ability to detect differences in light and dark areas

why do infants prefer to look at patterns of high visual contrast

because they have poor contrast sensitivity

reason why infants have poor contrast sensitivity

underdeveloped fovea

fovea

the central region of the retina

what is underdeveloped about the fovea

the cones (light-receptors) of the eye, which are concentrated in the fovea, differ from adults’ in size, shape and spacing (further apart than adults’)

what is highlight concentrated in the fovea + their role

light-sensitive neurons

involved in seeing fine detail and colour

implications of immaturity of children’s cone cells

limited colour vision - newborns have about 20/120 vision

can only see 2% of the light that comes through

colour vision of a one month old infant

cannot perceive differences between white and colour

age at which infants’ colour vision is similar to an adults’

2-3 months of age

colour vision ability of a young infant (before 2/3 months?)

can discriminate between two bright, vivid colours (high contrast) better than between two faint, pastel colours (low contrast)

infants are especially attracted to ___ stimuli

moving

way in which infants can actively control their own experience

visual scanning

difference in scanning abilities of a 1 month old vs 2 month old

1 month - scan the perimeters of shapes

2 month - scan both the perimeters and interiors of shapes

tracking abilities of infants till 4 months old

cannot track even slowly moving objects smoothly until 4 months old

smooth pursuit eye movements

viewer’s gaze shifts at the same speed and angle as a moving object, thereby keeping it in view

what later developmental outcomes can an infants’ skill at tracking moving objects predict

measures of cognition and attention 6 years later

when are infants drawn to faces

from birth

why are infants drawn to faces

general bias toward configurations with more elements in the upper half than in the lower half

when does an infant come to recognise and prefer their own mother’s face

after about only 12 cumulative hours of exposure

how can face perception provide hints about atypical development

atypical infants/toddlers have less interest in faces and therefore fewer opportunities to learn about information carried by faces e.g. social cues or speech sounds

perceptually narrowing

infants become better at discriminating among the kinds of faces that are frequently experienced in their environments

Pascalis et al findings on infants + adults ability to distinguish human and monkey faces (9 month old/adults vs 6 month old)

9 month old children + adults find it difficult to distinguish monkey faces

6 month old children are just as good at distinguishing monkey faces as human faces

explain Pascalis et al findings on infants vs adults ability do distinguish faces

younger infants are generalists while older infants and adults become specialists

explain young infants as generalists (perceptually narrowing)

infants hold onto ability to distinguish features of any kind

explain older infants/adults as specialists (perceptually narrowing)

discard the need to distinguish between irrelevant features e.g. monkey faces but retain the ability to distinguish human faces

2 facial preferences of infants

→ (from birth) infants look longer at faces that adults find more attractive

→ (after birth) infants develop preference for faces depicting gender of the caregiver they see most often (Quinn et al)

what face expertise do infants develop by 4-5 months old

the significance of different facial expressions

purpose of gaze-following for infants

allows infants to synchronise their visual attention with that of another person which provides them with insight into what that person is interested in/talking about

hypothesis of impact of covid-19 on gaze following

pandemic born infants’ gaze following skills might be enhanced due to mask wearing - infants more attuned to people’s eyes

pattern perception

analyse and integrate separate elements of a visual display into a coherent pattern

age at which infants achieve pattern perception

2 months old

perceptual constancy

the perception of objects as being constant size, shape and colour etc in spite of physical differences in retinal image of the object

when is perceptual constancy evidenced in a person’s life

early in life

how does evidence of perceptual constancy early in life support nativist position

visual experience does not seem to be necessary for perceptual constancy

object segregation

the perception of the boundaries between objects to be able to tell objects are separate

importance of movement for object segregation

a cue that indicates the boundaries between objects

what do young infants use to perceive object segregation

common movement

what older infants use in addition to common movement to perceive object segregation

additional sources of information e.g. gravity and other general knowledge about the world

when do infants being to develop depth perception

1 month e.g. respond to optical expansion

optical expansion

the visual image of an object increases in size as it comes towards us, covering up more and more of the background

example of a depth cue

optical expansion

explain a study proving 1 month old infants response to depth cues

Ball and Tronick found one-month-old infants will blink defensively at an object that appears to be heading towards them

importance of stereopsis

produces the perception of depth

stereopsis (stereoptic vision)

process by which the visual cortex combines differing neural signals caused by binocular disparity

binocular disparity

the slightly different signals sent to the brain by the two eyes

when do infants develop stereopsis

emerges suddenly at around 4 months old

which depth perception ability comes first

optical expansion is used before stereoptic vision

age at which infants become sensitive to monocular/pictorial cues

6-7 months

monocular/pictorial cues

perceptual cues of depth that can be achieved by one eye alone

3 perceptual cues of monocular cues

→ relative size (larger is closer)

→ interposition (overlapping)

→ linear perspective (convergence of parallel lines)

up till what age do infants/toddlers treat pictures as though they were real objects

19 months

nature of auditory perception at birth vs 5/6 years old

auditory system relatively well developed at birth

hearing approaches adult levels around 5/6 years old

auditory localisation

ability to detect where a sound is coming from

what 2 auditory skill do newborns/infants have

→ auditory localisation

→ perceiving subtle differences in human speech/sounds

3 infants’ perceptions of music

→ preference for ‘pleasing’ music sounds over others

→ respond to rhythm + temporal organisation

→ sensitive to melody

preference of taste at birth

sweet tastes

what does it suggest if infants prefer smell of their own amniotic fluid relative to that of another baby

newborns can perceive differences in smell

when does sensitivity to taste and smell develop

before birth due to mother’s eating habits/diet

do newborns prefer smell of breast milk or formula

breast milk, regardless of whether they have been breastfed of bottlefed

what occurs if newborns are exposed to certain tastes + smells

increases the likelihood of a later preference for those flavours/scents

what type of exploration dominates infants’ first few months

oral e.g. use of mouth to suck on their own fingers and toes, and any object

what exploration takes precedence over oral exploration

manual exploration - as infants gain greater control over their hand and arm movements

intermodal perception

ability to integrate information form two or more senses to create a perceptual experience

3 ways very young infants link senses into one representation

→ sight and sound

→ oral and visual

→ visual and tactile

what intermodal perception skill do 5 months old achieve

associate facial expression with emotion in voices (Walker-Andrews)