Often shortened to DOP, a claim for eyeless sight, whereby blind or blindfolded people are said to have the mysterious ability to read or recognize and describe colors without using their eyes. Sometimes the ability is said to be clairvoyance, but usually the claim is that parts of some people’s skin, especially fingertips and toes, possess light-sensitive organs that act as retinas.
The idea that blind people have the ability to see color by touch was discussed as early as 1772 and written about in Boswell’s Life of Samuel Johnson. At that time it was believed that different colors produced different kinds of surfaces, but the differences were said to be so fine that it was doubted whether they could be distinguished. In the 19th century, it was thought that each color has its own degree of heat and that it was this that could be detected by a blind person.