Final answer:
Eleanor Gibson used the visual cliff to measure a baby's depth perception abilities, which are deduced based on their willingness to crawl over an illusion of a cliff.
Step-by-step explanation:
Eleanor Gibson and her colleagues have used the visual cliff to measure an infant's ability to perceive depth perception. The visual cliff is an experimental apparatus that was designed to provide the illusion of a drop-off as a way to test babies' and young animals' willingness to crawl over a seemingly dangerous area. It consists of a glass-covered platform with a patterned surface beneath that creates the visual illusion of a cliff, while the glass surface provides solid support. The infants' perception of depth rather than their fear of heights is deduced by their willingness or reluctance to crawl across the glass.
This experiment is significant in the area of developmental psychology and provides insight into how and at what age depth perception develops in humans. It was found that when a baby is able to crawl, usually by around 6 months of age, they begin to show signs of depth perception. This has critical implications for understanding sensory and cognitive development and is also a poignant example of how experience and mobility contribute to the development of perceptual abilities.