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Marie Morita, Takao Sato; The underlying mechanism for detecting straight lines.. Journal of Vision 2018;18(10):415. doi: https://doi.org/10.1167/18.10.415.
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© ARVO (1962-2015); The Authors (2016-present)
The detection of straight lines is thought to be realized by balanced outputs from two mechanisms tuned for opposite curvatures (Blakemore & Over, 1976). To examine this supposition, we measured curvature detection thresholds after adapting straight and wavy lines. It was found that curvature detection thresholds were decreased (i.e. sensitivities were increased) after adapting to straight lines. In experiments, we measured curvature detection thresholds, i.e. discrimination thresholds between straight or sinusoidally wavy lines, after adapting to either straight or wavy lines. In the adaptation phase, the vertical adaptation stimuli were presented on both side (1 deg away) of the central fixation point for 5 sec. They were moved along 0.25-deg radius circle at a rate of 0.314 deg/s clockwise or counterclockwise. Then test stimuli, a pair of straight/wavy lines, was presented 1 deg to the right or left of fixation and observers judged which is straight. The threshold was measured by using constant method. The results indicated that detection thresholds after adapting to straight lines were smaller than those after adapting to wavy lines. The adaptation to straight lines should affect equally to the opponent curvature detection mechanisms that subserve curvature detection models based on Blakemore & Over's presumption, and should not affect curvature-detection thresholds. Thus, present results might suggest the existence of detection mechanisms for straight line that is tuned to straight lines instead of curvature.
Meeting abstract presented at VSS 2018
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