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At least 253 records · Page 14Linked to original sources
PubMed1993

Complete interocular transfer of motion adaptation effects on motion coherence thresholds.

The binocularity of visual mechanisms in humans can be investigated by measuring the interocular transfer (IOT) of visual aftereffects. Cells in extrastriate visual areas of macaque, e.g. the middle temporal (MT) area, are uniformly binocular, whereas cells in striate area V1 vary in their degree of binocularity. Therefore, IOT of aftereffects mediated by extrastriate cortex should be nearly complete compared to the partial transfer (about 70%) found for aftereffects thought to be mediated by V1. If MT and other extrastriate areas play a significant role in motion perception, then IOT of motion adaptation aftereffects on the perception of moving stimuli should be nearly complete. After motion adaptation, the perception of global movement direction in partially coherent random dot kinematograms (RDKs) is temporarily impaired if the predominant direction of dots in the test stimulus matches that of the adaptation stimulus. I measured the IOT of this motion incoherence aftereffect in four observers. Post-adaptation motion coherence thresholds were elevated equally for interocular and intraocular adaptation, indicating complete transfer of the aftereffect. Measurement of the classical motion aftereffect using the same stimuli and conditions showed partial or absent transfer. These data support the idea that extrastriate areas play a key role in motion perception and suggest that the motion incoherence aftereffect and the classical motion aftereffect may involve different mechanisms.

Adaptation, Ocular↗
PubMed1978

Form aftereffect contingent upon a colour shift.

After prolonged fixation of coloured gratings of low spatial frequency, images of the gratings can be elicited up to 90 min thereafter when the colour of a spatially homogeneous test field is suddenly changed. Only adapting gratings with luminance contrast induce clear aftereffects. Control experiments rule out afterimages as an explanation of the aftereffects.

Adaptation, Ocular↗
PubMed2002

Buildup and decay of a three-dimensional rotational aftereffect obtained with a three-dimensional figure.

Gaps in past literature have raised questions regarding the kinds of stimuli that can lead to three-dimensional (3-D) rotation aftereffects. Further, the characteristics of the buildup and decay of such aftereffects are not clear. In the present experiments, rotation aftereffects were generated by projections of cube-like stimuli whose dynamic perspective motions gave rise to the perception of rotation in unambiguous directions; test stimuli consisted of similar cubes whose rotation directions were ambiguous. In experiment 1, the duration of the adaptation stimulus was varied and it was found that the 3-D rotation aftereffect develops with a time constant of approximately 26 s. In experiment 2, the duration between adaptation and testing was varied. It was found that the 3-D rotation aftereffect has a decay constant of about 9 s, similar to that observed with 2-D motion aftereffects. Experiment 3 showed that the rotation aftereffects were not simple depth aftereffects. To account for these aftereffects and related data, a modification of an existing neural-network model is suggested.

Adult↗
PubMed2005

Stereoscopic depth aftereffects without retinal position correspondence between adaptation and test stimuli.

To clarify whether stereo-slant aftereffects are independent of stimulated retinal position, two experiments compared the magnitude of aftereffects between the following two conditions: when the adaptation and test stimulus fell on (1) the same retinal position, and (2) on different retinal positions separated by 0.5 degrees -20 degrees . In Experiment 1, disc- or ring-shaped surface consisting of random-dots was presented at the central or peripheral visual fields. In Experiment 2, rectangular surface was presented at the upper or lower visual fields. After two minutes inspection of a random-dot stereogram depicting a +/-30 degrees slanted surface, the observer adjusted the slant of the test stimulus to appear fronto-parallel. The results of the experiments showed that significant aftereffects were observed similarly in both conditions. Moreover, the separation nor the stimulus shape scarcely affected the magnitude of the aftereffects. Based on these results we concluded that the depth processing mechanism which operates independently from the stimulated retinal position is responsible for the depth aftereffects we found.

Adaptation, Physiological↗
PubMed1998

Stereodeficient subjects show substantial differences in interocular transfer of two motion adaptation aftereffects.

Interocular transfer (IOT) of two motion aftereffects was examined in subjects with normal and deficient stereopsis. Normal subjects showed complete (100%) IOT of motion adaptation on coherent motion thresholds, but only partial IOT of a conventional motion aftereffect, supporting suggestions that the latter aftereffect may be mediated at a lower level in the visual pathway than the extrastriate regions implicated in processing coherent motion. This idea was strengthened by an even greater dissociation between the extent of IOT of the two aftereffects among stereodeficient subjects who exhibited very low IOT of the conventional motion aftereffect, but high (> 87%) IOT of the coherence motion aftereffect.

Adaptation, Ocular↗