The July 2011 issue of the American Psychological Association’s Monitor on Psychology explores the life and work of psychologist Eleanor Gibson in its Time Capsule section. Elissa Rodkey, in “The Woman Behind the Visual Cliff,” describes the challenges Gibson encountered as a women seeking to become an experimental animal psychologist including a rebuff by Robert Yerkes: ““I have no women in my laboratory.” Later precluded from a position at Cornell University due to antinepotism rules, Gibson eventual collaborated

with Richard Walk, whose Cornell faculty status meant he had access to laboratory facilities. Together they conducted a series of experiments testing the effect of an enriched rearing environment on learning in rats. One experiment called for rats raised in the dark, and the invention of the visual cliff was the serendipitous result of Gibson’s and Walk’s attempt to get more use out of painstakingly dark-reared rats. To their surprise, the dark-reared rats avoided the glass-covered drop-off portion of the cliff, showing that they could perceive depth despite their lack of visual experience. Gibson and Walk found that a variety of species could discriminate depth by the time they could walk, and animals such as chicks and goats that walk at birth could immediately perceive depth.

Eventually, Gibson and Walk tested crawling babies on the cliff, using the presence of the babies’ mothers to motivate the infants to crawl. Their findings were published in Scientific American and covered in the popular press, including a feature in Life magazine. It quickly became one of psychology’s most famous experiments, its engaging photographs incorporated in numerous introductory textbooks.

The full piece on “The Woman Behind the Visual Cliff” can be read online here.