Temporal and spatial frequency tuning of the flicker motion aftereffect.
The motion aftereffect (MAE) was used to study the temporal and spatial frequency selectivity of the visual system at supra-threshold contrasts. Observers adapted to drifting sine-wave gratings of a range of spatial and temporal frequencies. The magnitude of the MAE induced by the adaptation was measured with counterphasing test gratings of a variety of spatial and temporal frequencies. Independently of the spatial or temporal frequency of the adapting grating, the largest MAE was found with slowly counterphasing test gratings (at approximately 0.125-0.25 Hz). The largest MAEs were also found when the test grating was of similar spatial frequency to that of the adapting grating, even at very low spatial frequencies (0.125 c/deg). These data suggest that MAEs are dominated by a single, low-pass temporal frequency mechanism and by a series of band-pass spatial frequency mechanisms. The band-pass spatial frequency tuning even at low spatial frequencies suggests that the "lowest adaptable channel" concept [Cameron et al. (1992). Vision Research, 32, 561-568] may be an artifact of disadvantaged low spatial frequencies using static test patterns.
Bex
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PJ
McGill Vision Research, Department of Ophthalmology, McGill University, Canada. bex@cvs.rochester.edu
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Mareschal
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D000221:Adaptation, Ocular; D000360:Afterimage / Q000502:physiology*; D005403:Fixation, Ocular; D006801:Humans; D009039:Motion Perception / Q000502:physiology*; D009903:Optical Illusions / Q000502:physiology*; D010364:Pattern Recognition, Visual / Q000502:physiology; D010775:Photic Stimulation; D011601:Psychophysics; D013997:Time Factors