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Kenzo Sakurai; Shape distortion illusion of circles without prolonged viewing. Journal of Vision 2014;14(10):247. doi: https://doi.org/10.1167/14.10.247.
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© ARVO (1962-2015); The Authors (2016-present)
Previous research on shape distortion illusion revealed that prolonged viewing of a circular shape in peripheral vision produces polygonal shape perception of the circle itself (Khuu, McGraw & Badcock, 2002 ECVP), and also produces a polygonal (e.g. hexagonal) afterimage (Ito, 2011). We found that the shape distortion illusion can be induced in a short period by presenting alternation of a circle and its inward gradation pattern. We measured the induction time (latency) of this distortion illusion produced by circle/gradation alternation, and compared it with the induction time produced by prolonged viewing of static circles. In experimental condition, stimuli consisted of 5 black line drawing circles placed around a central fixation cross on a white background, and they alternated with same size inward gradation patterns in which luminance increased gradually from periphery to center. The alternation rate (temporal frequency) was varied from 0.5 Hz to 8 Hz. In control condition, only static circles were presented on a screen. Observers fixed their head on a chinrest and viewed the display, and they were asked to report the induction time by pressing a response key as soon as they noticed the shape distortion. Results showed that the induction time of this distortion effect by circle/gradation alternation was shorter than that obtained from prolonged viewing of static circles at 2~4 Hz temporal frequency. These results suggest that presenting alternation of a circle and its inward gradation pattern promotes adaptation of cortical process responsive to curvatures and induces shape distortion illusion instantly.
Meeting abstract presented at VSS 2014
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