TEMPORAL AND SPATIAL-FREQUENCY TUNING OF THE FLICKER MOTION AFTEREFFECT

The motion aftereffect (MAE) was used to study the temporal and spatia l frequency selectivity of the visual system at supra-threshold contra sts, Observers adapted to drifting sine-wave gratings of a range of sp atial and temporal frequencies. The magnitude of the MAE induced by th e adaptation was measured with counterphasing test gratings of a varie ty of spatial and temporal frequencies, Independently of the spatial o r temporal frequency of the adapting grating, the largest MAE was foun d with slowly counterphasing test gratings (at approximately 0.125-0.2 5 Hz). The largest MAEs were also found when the test grating was of s imilar spatial frequency to that of the adapting grating, even at very low spatial frequencies (0.125 c/deg), These data suggest that MAEs a re dominated by a single, low-pass temporal frequency mechanism and by a series of band-pass spatial frequency mechanisms, The band-pass spa tial frequency tuning even at low spatial frequencies suggests that th e ''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. Copyright (C) 1996 Elsevier S cience Ltd.