They used a visual cliff and tested the reactions of infants at different ages to see babies’ reactions to the drop-off. The subjects were infants between 6 and 14 months, and their mothers. The infants where placed in the middle of the visual cliff while the mothers were asking them to crawl in their direction. Only three on 36 crawled in the mother direction over the virtual cliff.
Gibson and Walk concluded that depth perception is a survival ability. It was no possible saying that was an innate trait because infants were at least 6 months old.
Successively, in another