In Experiments 1-3, we monitored search performance as a function of target eccentricity under display durations that either allowed or precluded eye movements. The display was present either until observers responded, for 104 msec, or for 62 msec. In all three experiments an orientation asymmetry emerged: observers detected a tilted target among vertical distracters more efficiently than a ver...

Horizontal disparity tuning for dynamic random-dot stereograms was investigated for a large population of neurons (n = 787) in V1 of the awake macaque. Disparity sensitivity was quantified using a measure of the discriminability of the maximum and minimum points on the disparity tuning curve. This measure and others revealed a continuum of selectivity rather than separate populations of dispari...

Two sets of experiments were carried out to examine dependencies of two types of induced motion (motion assimilation and motion contrast) on spatial properties of stimuli in terms of spatial-frequency tuning of local motion detectors. In the first set, the magnitudes of motion assimilation and motion contrast for a sinusoidal grating were measured at a function of the spatial frequency of the i...

We have constructed "limited lifetime" stochastic motion stimuli using Gabor functions instead of dots, thereby controlling the local attributes of spatial frequency and orientation. Human psychophysical data for direction discrimination using these stimuli reveal two qualitatively distinct kinds of processing. For small displacements, direction discrimination performance as a function of displ...

Discrimination thresholds of spatial frequency and choice reaction times (RT) were measured in three subjects who performed a dual-judgment delayed discrimination task. Two reference gratings were presented side-by-side with a 0-800 msec stimulus onset asynchrony (SOA), which were followed after a 5-sec retention interval by two test gratings. Subjects judged which component changed and which i...

When a low spatial frequency noise mask is superimposed onto a luminance staircase, the perceived brightness pattern is dramatically altered although the edges remain visible. We measured contrast thresholds for the edges and for the illusory scalloping (Chevreul-illusion), as a function of noise center spatial frequency. The masking tuning functions overlapped, but peaked at different spatial ...

We report the results of psychophysical experiments with the so-called barber pole stimulus providing new insights on the neuronal processes underlying the analysis of moving features such as terminators or line-endings. In experiment 1, we show that the perceived direction of a barber pole stimulus, induced by line-ending motion, is highly dependent on the spatial frequency and contrast of the...

The data of Anderson and Burr [1985. Vision Research, 25, 1147-1154] on the temporal-frequency (TF) specificity of noise maskers indicate that the effect of TF masking is broad and varies across spatial frequency (SF) channels. One subtle but significant feature of the data is that the TF at which the effect of masking is maximal falls continuously as the test TF falls. This continuous shift is...

Several physiological studies in cats and monkeys have reported that the spatial frequency (SF) tuning of visual neurons varies depending on the luminance contrast and size of stimulus. However, comparatively little is known about the effect of changing the stimulus contrast and size on SF tuning in human perception. In the present study, we investigated the effects of stimulus size and luminan...

This study investigated the effects of the stimulus size on the spatial frequency tuning of the Ouchi illusion, which is an illusory sliding motion perceived in a checkerboard pattern of rectangular elements that is surrounded by a checkerboard pattern of orthogonally oriented elements. Two experiments were conducted to measure the perceived strength of illusion. The optimal size of the inner p...