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Anna Kosovicheva, Benjamin Wolfe, Patrick Cavanagh, Andrei Gorea, David Whitney; Dynamic recalibration of perceived space across the visual hemifields. Journal of Vision 2015;15(12):526. doi: https://doi.org/10.1167/15.12.526.
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© ARVO (1962-2015); The Authors (2016-present)
Visual input from the left and right visual fields is initially processed separately in the two cortical hemispheres, yet the visual system integrates these representations into a single continuous percept of space. In order to represent alignment and symmetry across the visual field, the visual system may continually recalibrate visual information across the hemifields. If so, any differences, such as misalignments across the two hemifields, should be adaptable. To test this, observers adapted to a set of large randomly rotating and moving colored lines in a circular Gaussian contrast aperture on a dark background, while performing a target detection task at fixation. The stimulus was split across the vertical meridian such that the lines in the left hemifield were shifted 1.8º higher than the lines in the right hemifield, or vice versa. An occluder strip (3.5º wide) eliminated visibility of the discontinuity in the lines at the vertical meridian, and observers were tested in a dark room with neutral density filter goggles to eliminate visual references. After 8 minutes of initial adaptation, observers performed a Vernier discrimination task in which they judged the relative positions of two brief (83 ms) horizontal lines straddling the vertical meridian. Vernier judgments reflected a negative aftereffect; an average shift of 0.08º in the direction of adaptation was required to null the perceived misalignment (p = 0.006). We replicated this result with adaptation to natural movies with the left and right halves of the image vertically misaligned. Results showed that a Vernier offset of 0.07º in the direction of adaptation was necessary to cancel the perceived misalignment (p = 0.02). Our results indicate that the visual system computes and dynamically recalibrates the relative alignment of elements across the visual fields—a mechanism that would help achieve and maintain continuous and stable perception of space.
Meeting abstract presented at VSS 2015
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