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The maximum displacement for the detection of apparent motion (Dmax) is measured using stimuli made up of Gabor function micro-patterns randomly distributed across the stimulus field. Previous studies using high densities of micro-patterns have demonstrated Dmax to be dependent on the spatial frequency content of the stimulus and not the size of the(More)
The detection of the direction of motion was measured as a function of the spatial and temporal offset for a kinematogram stimulus presented in two-frame apparent motion. The stimulus was made up of Gabor function micro-patterns randomly distributed across the stimulus field. We show that for short stimulus onset asynchronies (SOA) performance can be(More)
It has been demonstrated widely that at isoluminance moving chromatic stimuli are seen to be stationary or moving more slowly than their luminance counterparts. We have examined the effect on perceived velocity of adding luminance contrast to an isoluminant chromatic stimulus. We show that moving luminance contrast 'captures' colour so that a combined(More)
Direction discrimination was used to measure the minimum and maximum displacement for the detection of motion (Dmin and Dmax) for abruptly displaced sinewave gratings. This was measured for a range of contrast levels from 2 to 32 times the detection threshold for a range of spatially narrow band stimuli. Performance for Dmin (but not Dmax) was found to(More)
The motion aftereffect (MAE) was used to study the spatial frequency selectivity of suprathreshold motion perception. Observers were adapted to drifting sine-wave gratings confined to a retinal eccentricity of approx. 4 deg. The magnitude of the subsequent MAE was measured while viewing a stationary sine-wave grating test surface of one of a number of(More)
Previous research has demonstrated two categorically distinct mechanisms mediating apparent motion of kinematograms composed of eccentricity-confined, randomly placed Gabor micropatterns: a quasi-linear mechanism operating for high micropattern densities and short time separations, and a nonlinear mechanism operating at low micropattern densities or longer(More)
The maximum displacement for the detection of apparent motion is measured using stimuli made up of micro-patterns randomly distributed across the stimulus field. The micro-patterns were Gabor functions or half-wave rectified Gabor functions. Dmax is shown to be dependent of the spatial frequency content of the stimulus, and to be largely independent of the(More)
We measured directional sensitivity to a foreground pattern while an orthogonally directed background pattern was present under transparent motion conditions. For both foreground and background pattern, the speed was varied between 0.5 and 28 deg sec-1. A multi-step paradigm was employed which results in a better estimation of the suppressive or(More)
  • J C Boulton
  • 1987
The lowest velocity at which motion can be detected, the lower threshold of motion (LTM), has been investigated as a function of eccentricity. Results show that temporal properties of the LTM change with eccentricity, suggesting a dichotomy in the temporal properties of the neural mechanisms subserving this aspect of central and peripheral vision.(More)