Early Perceptual Development

what is the least developed sense at birth?

sight

DeCasper and Fifer (1980)

showed that a newborn with a pacifier connected to audio equipment would suck at whichever rate necessary to play their mother's voice as opposed to a stranger's

DeCasper and Spence (1986) - Cat in the Hat

showed evidence of memory from the womb; mothers read Cat in the Hat out loud several times a day in the final stages of pregnancy - newborns sucked their pacifier at a rate necessary to hear the familiar story

what can infants smell in the womb? what smell do they prefer after birth?

can smell waterborne odorants (food, perfume); show preference for smell of own amniotic fluid

DeSnoo (1937)

methods: injected sweet or bitter substance into amniotic fluid, fetus swallows it

results: fetus drank more of the sweet, less of the bitter -> same taste preferences as us

preference paradigm

infants turn toward/look longer at preferred stimuli

habituation

present stimulus repeatedly until response decreases (habituation) and then present novel stimulus and look for increase in response (dishabituation)

limitations of infant vision

nearsightedness, inability to make all color discriminations (grey vs. red, green, yellow), not good at getting image onto foveas

visual cliff experiment 1 - beginning vs. experienced

method: shallow end vs deep end, parent encouragement

results: 2/3 of beginner crawlers crossed cliff; none of experienced crawlers crossed cliff

conclusion: beginning crawlers have no fear of heights based on inexperience and lack of social referencing

visual cliff experiment 2 - all experienced

method: 4" drop vs 12" drop vs 40" drop, parent encouragement or fear based on condition

results: in uncertainty (12") if mom showed joy, cross; mom showed fear, do not cross; in no uncertainty ignore social referencing in both conditions to cross shallow or cross deep

conclusion: infants use social referencing in ambiguous situations, but are independent thinkers when there is no ambiguity

social referencing

looking to caregiver for info