Abstract
Two different motion mechanisms have been identified with motion aftereffect (MAE). (1) A slow motion mechanism, accessed by a static MAE, is sensitive to high-spatial and low-temporal frequency; (2) a fast motion mechanism, accessed by a flicker MAE, is sensitive to low-spatial and high-temporal frequency. We examined their respective responses to global motion after adapting to a global motion pattern constructed of multiple compound Gabor patches arranged circularly. Each compound Gabor patch contained two gratings at different spatial frequencies (0.53 and 2.13 cpd) drifting in opposite directions. The participants reported the direction and duration of the MAE for a variety of global motion patterns. We discovered that static MAE durations depended on the global motion patterns, e.g., longer MAE duration to patches arranged to see rotation than to random motion (Exp 1), and increase with global motion strength (patch number in Exp 2). In contrast, flicker MAEs durations are similar across different patterns and adaptation strength. Further, the global integration occurred at the adaptation stage, rather than at the test stage (Exp 3). These results suggest that slow motion mechanism, assessed by static MAE, integrate motion signals over space while fast motion mechanisms do not, at least under the conditions used.
Highlights
Two different motion mechanisms have been identified with motion aftereffect (MAE). (1) A slow motion mechanism, accessed by a static MAE, is sensitive to high-spatial and low-temporal frequency; (2) a fast motion mechanism, accessed by a flicker MAE, is sensitive to low-spatial and high-temporal frequency
The results showed that the MAE direction was opposite to the high spatial frequency components in the static test and that of low spatial frequency components in the flicker test for all conditions except for single patch of contraction
Such patch-number dependence is exclusively found under a static MAE, indicating that a slow motion mechanism is sensitive to global motion while a fast motion mechanism is not
Summary
Two different motion mechanisms have been identified with motion aftereffect (MAE). (1) A slow motion mechanism, accessed by a static MAE, is sensitive to high-spatial and low-temporal frequency; (2) a fast motion mechanism, accessed by a flicker MAE, is sensitive to low-spatial and high-temporal frequency. Two types of local motion detectors are often assumed that are distinct in terms of temporal c haracteristics[22,23,24,25,26,27,28,29] Among these studies, Shioiri and Matsumiya[23] developed a motion aftereffect (MAE) technique to isolate fast and slow motion mechanisms with a test stimulus under different temporal conditions. Sensitivity to relative motion is effective to spatially integrate motion direction signals, and narrow orientation tuning provides more precise direction information coding These properties enable slow motion mechanisms to contribute more to global motion with complex spatial variations, such as rotation, expansion/contraction, biological motion than fast motion mechanisms. These studies suggest that both fast and slow motion signals can be used for processing global motion
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