Separate motion-detecting mechanisms for first- and second-order patterns revealed by rapid forms of visual motion priming and motion aftereffect.

摘要

Fast adaptation biases the perceived motion direction of a subsequently presented ambiguous test pattern (R. Kanai & F. A.Verstraten, 2005). Depending on both the duration of the adapting stimulus (ranging from tens to hundreds of milliseconds)and the duration of the adaptation-test blank interval, the perceived direction of an ambiguous test pattern can be biasedtowards the same or the opposite direction of the adaptation pattern, resulting in rapid forms of motion priming or motionaftereffect respectively. These findings were obtained employing drifting luminance gratings. Many studies have shown thatfirst-order motion (luminance-defined) and second-order motion (contrast-defined) stimuli are processed by separatemechanisms. We assessed whether these effects also exist within the second-order motion domain. Results show that fastadaptation to second-order motion biases the perceived direction of a subsequently presented second-order ambiguoustest pattern with similar time courses to that obtained for first-order motion. To assess whether a single mechanism couldaccount for these results, we ran a cross-order adaptation condition. Results showed little or no transfer between the twomotion cues and probes, suggesting a degree of separation between the neural substrates subserving fast adaptation offirst- and second-order motion.