WJEC Psychology Psy 2 Core Studies

WJEC Psychology Psy 2Core Studies Gibson, E. J. and Walk, P. D. (1960) The "Visual Cliff"

Aims • To find out if the ability to perceive depth is innate (in born) or learned.

Method • Laboratory experiment using a repeated measures design.

Participants • 36 babies aged between 6 months and 14 months and their mothers. • All babies were able to crawl.

Procedures • The researchers created a ‘visual cliff’ – a glass topped table that could safely support the weight of each infant. • A check patterned table cloth was positioned beneath the glass on one side of the table (the shallow side) and four feet below the glass on the other side (the deep side). • This gives the impression of a steep drop at one end of the table (the visual cliff).

Procedures • Each child was placed in the centre of the visual cliff on a centre board. • Their mother then called them from the cliff side and then from the shallow side. • The infants were encouraged to crawl over the edge of the visual cliff in order to reach their mother.

Procedures • Non-human animals were also tested (lambs, cats, rats, kids, chicks and goats). • The chicks, kids and lambs were of particular interest because they could stand and be tested within 24 hours of birth.

Findings • 27 of the infants crawled on to the shallow side at least once. • 3 attempted to crawl on to the ‘deep’ side. • Many of the infants crawled away from their mother when she called them from the deep side. • Others cried when she stood there because they could not reach her without crossing the ‘deep’ side.

Findings • Chicks of less than 24 hours old would always hop off the centre board on to the shallow side. • Kids and lambs (can be tested as soon as they can stand not long after birth) never stepped on to the ‘deep’ side. • Rats (depend on their whiskers to navigate, rather than visual cues) showed little preference.

Findings • Kittens (although rely on whiskers, also use visual cues as they are predators) at four weeks old showed preference for the shallow side and ‘froze’ when placed on the deep side.

Conclusions • For a species to survive it needs to develop depth perception by the time babies are able to move independently. • In some species this was true a few hours after birth. • This supports the biological theory that depth perception is innate.

Evaluation • The visual cliff was an ingenious design and was the first successful procedure for measuring depth perception in infants. • It allowed depth perception to be investigated in a safe environment. • They tested non-human animals as well as humans to see if the theory held up across species.

Evaluation • There are ethical issues with using humans and non-humans. • The sample size (36 infants) was relatively small. • The age range of the infants was large considering they were meant to be only just capable of crawling. • By the time babies can crawl they may have learned depth perception.

WJEC Psychology Psy 2 Core Studies