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Michael W. Grünau, David DiLenardo; Evidence for multiple motion aftereffects for radial flowfield stimuli. Journal of Vision 2002;2(7):372. doi: 10.1167/2.7.372.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose. The motion aftereffect (MAE) and interocular transfer (IOT) can be used to probe the human visual system for characteristics and location of motion mechanisms. In the present study, we used these techniques to examine several radial flowfield stimuli, which differed in motion coherence and dot lifetime (LT), by measuring direct and transfer MAEs with static and dynamic test stimuli. Methods. Adaptation stimuli were random dot expanding radial flowfields with acceleration, viewed by one eye. We compared a 100% coherent, infinite LT stimulus to a 100% coherent minimal LT stimulus and an infinite LT stimulus matched to the latter in terms of motion salience (35% coherence). The duration of direct MAEs was measured in the same eye, and that of transfer MAEs in the opposite eye. Results. Direct and transfer static MAEs were shortest for the incoherent stimulus, longer for the minimal LT stimulus and longest for the infinite LT stimulus, with transfer being partial (about 25%) for all. Direct dynamic MAEs were longer than static MAEs, with the coherent stimuli giving longer MAEs than the incoherent stimulus. IOT was around 50% for the coherent stimuli, irrespective of LT, and almost 90% for the incoherent stimulus. Conclusions. The results with the static test reveal mainly monocular mechanisms dependent on the coherence and LT parameters (low level). In addition, the dynamic test provides evidence for the strong involvement of binocular mechanisms that integrate over time. In the case of the incoherent stimulus, the mechanism is almost totally binocular, indicating that spatial integration can be achieved only at high binocular levels.
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