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Chris Paffen, Maarten van der Smagt, Tanja Nijboer; Color-grapheme synesthesia affects binocular vision. Journal of Vision 2012;12(9):682. doi: 10.1167/12.9.682.
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© ARVO (1962-2015); The Authors (2016-present)
In color-grapheme synesthesia, non-colored graphemes are perceived as being inherently colored. In recent years, it has become evident that synesthesia-inducing graphemes can affect visual processing in a manner comparable to real, physical colors. Here, we exploit the phenomenon of binocular rivalry in which incompatible images presented dichoptically compete for conscious expression. Importantly, this competition only arises if the two images are sufficiently different; if the difference between the images is small, the images will fuse into a single, mixed percept. We presented synesthetes and pair-matched controls with different achromatic graphemes (e.g. the digit 2 for the left eye and the digit 5 for the right), which did not lead to significant periods of binocular rivalry in controls. However, achromatic graphemes that induced synesthetic color percepts (i.e. only in synesthetes) evoked significant periods of binocular rivalry. That is, compared to achromatically perceived graphemes, synesthesia-inducing graphemes increase the predominance of binocular rivalry over binocular fusion. This finding shows that the synesthetic color experience can provide the conditions for evoking binocular rivalry, much like stimulus features that induce rivalry in normal vision. In addition, the results suggest that the synesthetic color experience is interacting at the stage where monocular visual information from two eyes leads either to binocular fusion or binocular rivalry.
Meeting abstract presented at VSS 2012
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