Abstract
Purpose: Visual motion is a special kind of information: since it loses its behavioral relevance quickly, it is crucial for time-constrained behavior. For this reason, one might expect that visual motion should be rapidly available to motor systems as well as to perception. We examined whether visual motion information in one region of the visual field influences fast reaching movements to, as well as perception of, an object in another part of the field and compared the time courses for these two measurements. Methods: A square wave grating translated vertically on a monitor and then reversed direction. A brief stationary flash was presented next to the grating (separated by ∼10 deg) at various times before or after the grating reversed direction. The endpoint accuracy of reaching movements to the flash was measured and compared to perceptual localization of the flash using the same stimulus. Results: Perceptual task: The flash appeared shifted in the direction of the nearby grating's motion. Motor task: Reaching endpoints were also shifted in the direction of the nearby motion. The time course of the reaching mislocalizations was consistent with that of the perceptual illusion. Conclusions: The motion of one object influenced reaching movements to a spatially-separated stationary object, showing that, unlike many other kinds of visual information, motion signals over large regions of the visual field are taken into account before manual localization takes place. The mechanism(s) subserving perceptual and motor localization share a common motion input. Supported by NIH.