exam 2: perceptual development

Moss and Robson hypothesized infants who spent more time in awake, alert, non-irritable states…

better at visual tasks

Moss and Robson (gender diff)

boys who were more awake at 1 month, fixated > on social stimuli at 3 months

maternal assessment of infant temperament

boys (but not girls) whose mothers viewed them as > fussy or demanding spent < time looking at geometric designs

boys who were quieted by visual stimuli looked longer at social and geometric stimuli

2 types of photoreceptors

rods and cones

rods

detect only light and dark and are very sensitive to low light levels (night vision)

cones

detect color, fine detail and are concentrated near the center of your vision (fovea)

3 types of cones in humans

short wavelength blue (~10%)

medium wavelength green (~30%)

long wavelength red (~60%)

lack of color vision

partial or complete lack of cones in retina

mostly congenital, passed from mother to son

some later in life - disease, trauma, toxic effects of drugs, metabolic disease, or vascular disease

deuteranopia

type of red-green color blindness

protanopia

type of red-green color blindness

tritanopia

blue-yellow color blindness

color constancy

perceive familiar objects as having consistent color even when changes in light and shadow filter light reflected by object

adults have this

no info on this in children

color sensitivity

consequence of immature fovea: babies at first have poor color vision

fovea

responsible for daylight vision, fine detail, rich color vision

adult fovea (mature) - 65%

infant (not os much) - 2%

at birth, infants do not appear to perceive difference between…

white and color

by 2-4 months, infants’ color vision is…

similar to adults

what do infants do with color?

perceive and categorize

2 systems for representing color

right and left hemispheres

right hemisphere

language-free

present from infancy

left hemipshere

language-dominant

language-based categories acquired throughout development

usually dominates right hemisphere color representations

Sapir-Whort hypothesis (linguistic relativity)

structure of a language determines a native speaker’s perception and categorization of experience

grammar, language you speak, verbal structure of your language influences the way you perceive the world

functional near-infrared spectroscopy

optical imaging that measures neural activity by looking for metabolic changes that lead to differential absorption of infrared light in brain tissue

infrared light transmitted to the brain and absorption detected by optical fiber skullcap or headband

Yang et al (2016)

5 month old brains responded to change from a color in one category to a different category

infant brains represent some color categories before learning a label for them

Skelton et al (2017)

systematically mapped infants’ categorical recognition for hue onto stimulus array

infants have categories for red, yellow, green, blue, and purple

color categorization partly organized and constrained by bio mechanisms of colo vision and not arbitrarily constructed by language

optokinetic nystagmus

fixate on a point in a large pattern, follow it with smooth eye movement until out of sight, eye jerk back to center of the visual field

saccade

rapid, ballistic eye movement that puts object of interest into central focus

tracking

smooth pursuit

newborns track single moving objects in an arc of 90 degrees

develops by 6-8 weeks and continues to anticipatory pursuit

very young infants look at areas of high…

contrast

scanning faces

1 mo old: scan perimeter of high shapes, begin to refine to high contrast and eyes

2 mo old: scan perimeters of shapes and interiors of shapes; “triangle'“

attention

some sensory input is selectively processed over other information

overt attention

move eye to focus on a particular object or location

covert attention

shift attention without moving eyes

visual salience

things stand out against a background

attentional capture

green circle < red diamond

what influences attention?

observer’s interest and goals (vary by observer and goal)

interaction with the environment/task demands

inattentional blindness

missing something you are looking directly at

change blindness

difficulty detecting a difference even though it is obvious when you know to look for it/ where to look (e.g. editing errors in films)

joint attention

infant and parent looking at the same object at the same time

novelty preference method

infants prefer (look longer at) novel over familiar stimuli

show stimulus until familiar

pair familiar and novel stimuli

if prefer novel, if they can distinguish

clear adaptive value

If infants can see similarities between things, and then focus attention on new things

memory testing: recognition

noticing whether identical/similar to previously experienced stimulus

Strauss and Cohen

habituated 5-month-olds to objects with a particular size, color, form, and orientation

testing: alternative object

results: Immediate

15 min delay: color and form

24-hour delay: form

memory testing: recall

remembering a stimulus or event when it is not present

habituation

tells us something about memory

recognition of stimuli: subsequent trials < time

can last for days to weeks, depending on stimulus

(Quinn et al.)

familiarization trials: one each trial, 2 color photos of cat or dogs

trials: all different cats or dogs

test trials: novel cat and novel dog

results: preferred the novel

familiarized with cats, preferred dogs during the test

familiarized with dogs, preferred cats during the test

capable of perceptual categorization

visual recognition

being able to recognize something = efficiency in learning about the world

figure-ground relationship

organization of visual field into objects (figures) that stand out from their surrounding environment (ground)

we tend to organize things by…

proximity - group nearby figures together

continuity - smooth continuous patterns (ignore the “broken”)

closure - fill in gaps to create whole objects (Illusory triangle)

subjective contour

visual illusion that evokes perception of an edge or figure

perceptual constancy

adults (and infants?) perceive a constant

2 types of constancies: shape and size

Emmert’s Law (1881)

if retinal image of 2 different objects at 2 different distances are the same, the physical size of the object that is farther away must be larger than the one that is closer

Slater et al. 91990) Familiarization

showed newborns a large or small cube at varying distances

cube’s size remained the same

size of retinal image changed from trial to trial

results: longer look (suggests that they could tell the difference in spite of the same retinal size)

object perception: top-down

using previous knowledge

object perception: bottom up

building with sensory perception to conception

object perception: theoretical perspectives

nature/innate vs nurture/constructed

constructivist theory (piaget)

objectification: knowledge of the self and external object as distinct entities, spatially segregated, persisting across time and space, obeying causal constraints

nativist theory

Spelke, Baillargeon, etc: initial unlearned knowledge forms a central core around which more mature cognitive capacities are elaborated

three classes of depth cues

kinetic/motion - carried/dynamic cues/oculomotor cues (some super-early, most before 3-4 months)

binocular depth cues (3-5 months)

static monocular/pictorial (5-7 + months)

kinetic

movement helps with perception of depth

oculomotor

eye movement; convergence, accommodation “Feelings in your eyes”

your movement

target object’s movement

monocular

only need one eye to see depth

binocular

information from 2 eyes helps perceive depth

convergence

the degree to which your two eyes must turn inward to focus on an object

motion parallax

perceived relative motion (difference you perceive in movement between near and far objects)

deletion

covering of the farther hand

accretion

uncovering of the far hand

kinetic depth effect

as the viewer moves around a stationary object or as different parts of a moving object are presented to the viewer, retina is presented with many images of the object

binocular cues

slightly later (3-4.5 months)

2 eyes: receive different images as input

binocular (retinal) disparity

difference between the retinal image of an object coming from each eye

2 slightly different signals are sent to the brain

basic of what is called stereoscopic vision

4 months

stereosepsis

visual cortex fuses 2 different retinal images (neural input) caused by binocular disparity into a single 3D image

monocular depth cues

static monocular

pictorial depth cues

later ability (emerges between 5-7 months perhaps maybe later?)

pictorial cues

(static) monocular depth cues

can perceive depth even if one eye is closed

most of them emerge by 7 months of age

interposition

near objects partially hide (occlude) objects that are farther away

relative height

other things being equal, distant objects appear higher in your field of vision

objects that are higher are usually farther away

relative size

the larger an object appears, closer the object is to the viewer

relative clarity/aerial (atmospheric) perspective

distant objects are less clear than nearby objects

Yonas, Cleaves, and Peterson hypothesis

if an infant were sensitive to the pictorial information for depth specified in the trapezoidal window, they would reach the apparently nearer side

in 5 months prenatal, ears and nose begin to develop…

cartilage

when does a fetus respond to sound?

25-30 weeks

timbre

harmonic structure of a tone

quality of a sound that distinguishes it from other sounds with the same loudness, pitch, and duration

auditory localization

figuring out where the sound sources are in that space

sound loco: azimuth

right to left

sound loco: elevation

up and down

sound loco: distance

how far the sound is from the listener

sensitive period

a time when the sound-localization system is best able to adapt to changes in the environment on the basis of input

moro reflex

present prenatally (25 weeks)

startle

stimuli postnatal : failing to support or hold neck, head and loud, sudden noise

arms of baby thrust outward and then embrace as fingers curl

peaks at 1 month, begins to disappear at 12 weeks, disappears at 6-7 months

presbycusis

gradual hearing loss, usually age-related; affects the sense organ

Kisilevsky et al

used recorded HR of newborns

found inc HR to mom’s voice and dec HR to a stranger

Used HR because can use pre and post-natal

preference for all 4

infants attend to speech that is likely to be…

relevant to them

Infants can discriminate between phonemes that do not occur…

in their native language