In a number of tests, D. B. reported an impression of ‘waves’ generated by some visual stimuli, especially in a ‘lively’ part of his field defect (a region between the fovea and about 30° in the lower quadrant). The waves could have some ‘sort of form’, or could be ‘quick’, ‘slow’, ‘sharp’, or ‘curved’. When the waves were experienced they were difficult for him to ignore, but they could seriously mislead him when they were used as a basis for differential discriminations. Accordingly, special pains were taken to see whether good discrimination was still possible when conditions were arranged to eliminate the waves. This was done by increasing ambient illumination with bright overhead lamps or by using low contrast stimuli. The results showed that his discrimination was still excellent in a variety of situations, even though he reported ‘nothing there’, ‘absolutely nothing’, or ‘just guessing’. D. B. often seemed to settle into a sort of experience-less ‘blindsight mode’ when he performed well but automatically and without fatigue, in contrast to his good field when long series of discrimination tests produced tiredness.
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