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H.K. Falkenberg, P.J. Bex; Motion perception across the field . Invest. Ophthalmol. Vis. Sci. 2004;45(13):4361.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose:To investigate the perception of motion and optic flow as a function of retinal location, with a view to determine the likely functional deficit in low vision patients with central and peripheral visual field loss. The results reported here are from a preliminary study investigating two normal observers. Methods:Apparent speed, speed discrimination sensitivity and global motion coherence thresholds were measured as a function of retinal location with random Gaussian dot patterns in which target dots moved in a global pattern of rotation, translation or expansion/contraction and noise dots moved in random directions. Apparent speed was measured by adjusting the apparent speed of a foveal target to match that of a peripherally–viewed target with a staircase procedure. Speed discrimination thresholds and motion coherence thresholds were measured with a 2AFC procedure. Results:Motion coherence thresholds and speed discrimination sensitivity were invariant of eccentricity and location in the visual field. In addition, there was no significant difference among the motion stimuli tested. The speed matching experiment showed that expanding and contracting dot patterns were perceived as moving significantly faster in the periphery than centrally, whereas this was not found for rotating or translating motion. Conclusions:The observation that moving dot patterns containing the same distribution of element speeds can appear to move at different global rates suggests that distinct mechanisms process different patterns of complex motion. In spite of this, motion coherence thresholds and speed discrimination sensitivity were invariant across the field and both were relatively constant for different global motion patterns. This implies that patients with central or peripheral visual field loss would not be expected to show selective impairment in optic flow–based tasks (such as mobility), simply on the basis of the location of their scotoma.
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