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Elizabeth Seckel, V.S. Ramachandran; Blindsight: enhanced visual puzzle-solving and memory in synesthesia. Journal of Vision 2013;13(9):1326. doi: 10.1167/13.9.1326.
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© ARVO (1962-2015); The Authors (2016-present)
EA experienced colors when she saw printed letters of the alphabet and numbers. We used three different kinds of puzzle pictures that contained hidden letters which required 30 seconds or more for normal people to identify. EA recognized them three times faster. She said that the colors were evoked prior to conscious letter recognition; clueing her as to what the letters were. She also saw mirror reversed letters the same colors as non-reversed which enabled her to read mirror-reversed text at thrice the normal speed. Thus in some synesthetes colors are evoked preconsciously early in sensory processing. These results remind us of 'blindsight' seen in patients with blindness caused by lesions confined to V1 (WeizKrantz 1986). Analogously, we suggest that in EA the graphemes are processed unconsciously up to the fusiform and cross - activate color cells in V4 before the information is transmitted higher up where the color is utilized to infer the grapheme. We had previously noted (Ramachandran and Brang, 2009) that some lower (projector) synesthetes are better at other unrelated visual tasks such as visual eidetic memory (e.g. finding Waldo even after the picture is briefly shown and removed) and suggested that this - along with their other creative skills - might result from a more widely expressed 'cross connectivity' gene, especially in the visual domain. If so, the possibility exists that EA's skill in tasks is a manifestation of a more general facility with visual puzzles (which would be even more interesting if true!) But her subjective remarks, "I see the colors before I see the shapes" strongly support the blind-sight interpretation. The two hypotheses are not mutually exclusive, of course, and we are currently disentangling them using Shepard’s mental rotation and other visual puzzles.
Meeting abstract presented at VSS 2013
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