PubMed · 5245384
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E H Heinrichs. 1968. The single ape.. https://pubmed.ncbi.nlm.nih.gov/5245384/
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Two recent versions of a single channel model of motion perception have had impressive success in explaining direction discrimination by human observers for spatially filtered noise images in two-flash apparent motion. It has been argued that the dramatic breakdown in motion perception which occurs when one image in the two-flash sequence is low-pass filtered can be explained only by a single channel model. We show that neither version of the single channel model which has been proposed can explain performance for noise images chosen to provide comparable stimulation in the spatial channels known to subserve human vision. A multi-channel model of motion perception has little difficulty in explaining these results.
A prerequisite for higher-level visual tasks such as object recognition is a segmentation of the image into distinct two-dimensional regions. While it has long been assumed that the human visual system jointly exploits region and boundary cues for image segmentation, we report the results of psychophysical experiments which suggest that the visual system relies on geometric properties of bounding contours such as closure and not on the texture of the two-dimensional regions they partition. These findings suggest that the visual system may code and links contours into coherent shapes before surface properties are conjoined.
Thresholds were measured for five tasks: line detection, intensity discrimination, two-line resolution, vernier acuity and line-orientation discrimination. For each task, 30 arcmin lines were presented foveally in eight retinal meridians to assess similarities in orientation anisotropies across tasks in the same observer. Three observers were tested. The pattern of the orientation anisotropy differs across tasks. Meridional anisotropies exist in detection, increment discrimination thresholds, and vernier acuity but the classical oblique effect is consistently found only in orientation discrimination.