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David Chan, Mary Peterson, Sam Qian, Jay Pratt; The "Gist" of Visual Processing. Journal of Vision 2012;12(9):1058. doi: 10.1167/12.9.1058.
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© ARVO (1962-2015); The Authors (2016-present)
Visual information in humans is processed by two separate visual pathways. One is the magnocellular visual pathway (M-pathway), which carries high temporal frequency information but low spatial frequency information. The other is the parvocellular visual pathway (P-pathway), which carries low temporal information but high spatial information. Moshe Bar and colleagues (2007) presented participants with high and low spatial frequency images and found that participants made faster and more accurate categorization responses to the low spatial frequency images. They hypothesized this was due to low spatial frequency "gist" information being rapidly carried by the M-pathway that helps support rapid object perception. In order to directly test the involvement of the M-pathway in "gist" processing, we used red diffuse light, which selectively inhibits the M-pathway (e.g., West, Anderson, & Pratt, 2010) but leaves the P-pathway activity untouched. In our experiment, we presented participants with low and high spatial frequency images under either red or green (control condition) diffuse light and asked them to judge whether the object was larger or smaller than a shoebox. We replicated the original finding of an advantage in categorizing low spatial frequency images, and found this advantage existed under both green and red light conditions. Thus, it does not appear "gist" processing is uniquely carried by the M-pathway. In addition, we found that responses were much faster overall with red diffuse light than green diffuse light. Given that inhibiting one pathway can bias activity in the other pathway ((Yeshurun, 2004), the faster responses under red diffuse light may reflect a processing advantage is the object perception P-stream. In this case, processing with a single visual stream may provide faster responses than when two streams are working in parallel.
Meeting abstract presented at VSS 2012
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