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Matthew Harrison, Gennady Erlikhman, Gideon Caplovitz; Rotating squares made out of drifting Gabors: the contributions of velocity and position based motion information to the perceived speed of a rotating object.. Journal of Vision 2016;16(12):666. doi: https://doi.org/10.1167/16.12.666.
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© ARVO (1962-2015); The Authors (2016-present)
A static Gabor patch containing a drifting sinusoidal grating appears to be displaced in the direction of the carrier motion. We introduce a novel 'rotating square' illusion in which drifting Gabor elements positioned to form a square, together give rise to a global rotational motion percept. This is accomplished by selecting the drift speed of each Gabor to match the component motion speed that would be expected for a physically rotating square. We use this stimulus to investigate the role of local 1st order 1D component motion in the representation of global rotational motion. In a series of psychophysical experiments we compare the perceived rotational speed of these illusory rotating squares to the speed of physically rotating squares across a variety of stimulus speeds and sizes. We find that across a range of rotational speeds less than 24/sec, when the squares were large so that individual elements fell in the periphery, the perceived illusory rotational velocity of the squares was equivalent to a physically rotating square with the same perpendicular motion components. This suggests that the pooling of local 1st order 1D component motion signals can fully account for the perceived speed of a rotating square. However, when the squares were smaller and elements were more centrally located, the perceived rotational velocity was slower in the illusory condition than for physically rotating squares. In this case, position-based motion information commonly associated with 2nd order motion (Seiffert & Cavanagh 1998,1999), contributes to the perceived rotational speed of a luminance-defined 1st order rotating square.
Meeting abstract presented at VSS 2016
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