D.B. (blindsight patient)
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Blindsight overview
Blindsight is the condition in which a person is able to respond to a visual stimulus without consciously perceiving it. The visual cortex, also called V1 or the striate cortex, receives input from the retina which makes visual discrimination possible. When V1 is removed, however, it is sometimes still possible to make "visual" discriminations because the input from the retina travels through other areas in the brain, which may also be the reason this phenomenon occurs. [1]
Origin of D.B.'s blindsight
D.B. is the first and most intensively studied case of blindsight. D.B.'s blindsight was caused not by brain damage but by the removal of a non-malignant tumor from his right visual cortex at the age of 26 which subsequently left him unable to detect things in his left visual field. [2]
Weisenkrantz and Warrington study
Psychologists L. Weisenkrantz and Elizabeth Warrington first began studying D.B. in 1973 at the National Hospital in London. D.B. was tested with a "monkey-type" in which he was given no prompting for what he was looking for and was simply asked to reach out and touch the stimuli or to "guess" about what was being presented to him.
D.B. responded by successfully making "guesses" about things that he said he couldn't see. He was able to tell which direction grating was set and whether an object was moving or not. He could also reach for objects without consciously being aware of their presence. In fact, a great deal of the tests he participated in were all about guesswork, rather than conscious though, in D.B.'s mind and he was shocked when he was shown how accurate he had been across the board.
After Weisenkrantz and Warrington published a book about their work with D.B. and blindsight in 1986, the two worked with D.B. again in 2007 and noted that his sensitivity had increased considerably. [3]
References
Blindsight Consciousness and Cognition: Prime-sight and blindsight
