Frederick A. A. Kingdom

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Contrast thresholds for stereoscopic depth identification (crossed or uncrossed) were measured as a function of disparity by use of isoluminant (red-green) and isochromatic (yellow-black) 0.5 cycles/deg Gabor patches. For the purposes of comparison, stimulus contrasts were scaled by their respective detection thresholds. The Gabor patches could be either(More)
Contrast thresholds for stereoscopic depth identification (crossed or uncrossed) were measured as a function of disparity using isoluminant (red-green) and isochromatic (yellow-black) 0.5 c/deg Gabor patches. For the purposes of comparison stimulus contrasts were scaled by their respective detection thresholds. The detection thresholds employed were(More)
The color vision of Old World primates and humans uses two cone-opponent systems; one differences the outputs of L and M cones forming a red-green (RG) system, and the other differences S cones with a combination of L and M cones forming a blue-yellow (BY) system. In this paper, we show that in human vision these two systems have a differential distribution(More)
Under what circumstances is the common motion of a group of elements more easily perceived when the elements differ in color and/or luminance polarity from their surround? Croner and Albright (1997), using a conventional global motion paradigm, first showed that motion coherence thresholds fell when target and distractor elements were made different in(More)
The ability of the visual system to detect stimuli that vary along dimensions other than luminance or color--"second-order" stimuli--has been of considerable interest in recent years. An important unresolved issue is whether different types of second-order stimuli are detected by a single, all purpose, mechanism, or by mechanisms that are specific to(More)
We sought to determine whether the detection and the identification of texture modulations are mediated by a common mechanism. On each trial two textures were presented, one of which contained a modulation in orientation (OM), spatial frequency (FM), or contrast (CM). Observers were required to indicate whether the modulated texture was presented in the(More)
There is considerable interest in how humans estimate the number of objects in a scene in the context of an extensive literature on how we estimate the density (i.e., spacing) of objects. Here, we show that our sense of number and our sense of density are intertwined. Presented with two patches, observers found it more difficult to spot differences in(More)
Subjects matched the brightness of test patches whose inner (adjacent) surrounds appeared either as transparent overlays on a wider background that included the test patch or as regions differing in reflectance from the test patch and the outer surround. In the above configurations the luminance and spatial extent of the inner surround was identical, thus(More)
It has recently been shown that the visual system is more sensitive to uniform color and/or luminance changes applied to raw compared to phase-scrambled images of natural scenes (A. Yoonessi & F. A. A. Kingdom, 2008). Here we consider whether the mechanisms responsible for the differential sensitivity operate before or after the point at which the signals(More)