FOURSITES

Prolonged exposure to moving stimuli gives rise to direction-selective loss in detection sensitivity (direction-selective adaptation: DSA), and illusory backward motion in static and dynamic test stimuli (static MAE and dynamic MAE). Previous studies, including ours, have shown that the three motion aftereffects have distinct properties with regard to sensitivity to second-order motion, spatial-frequency selectivity, temporal tuning and interocular transfer. In addition, our recent findings suggest that the flicker MAE is composed of low- and high-level components. The low-level component is mostly monocular, predominates in the periphery, is immune to attentional modulation, and is selective to stimulus type (first-order / second-order). The high-level component is binocular, predominates in the central visual field, is affected by attention, and is non-selective to stimulus type. These results support a functional structure of the motion system, in which first-order and second-order motion signals are primarily processed in separate pathways, each consisting of multiple scale channels, and the outputs of the two pathways are integrated at a later stage.