Temporal and Spatial Constraints of Action Effect on Sensory Binding

Previous studies have shown that asynchrony in perceived changes in the visual attributes of an object is attenuated when the object is the target of a manual reaching action (e.g. Corveleyn et al. in J Vis, 2012. doi: 10.1167/12.11.20 ). In the present study, we examined the temporal and spatial constraints associated with the effect of action on sensory binding. Participants performed a temporal order judgment task which required them to judge which changed first, the position or the colour of a visual stimulus, either while performing a concurrent motor task (manual acquisition of a visual target) or not (perceptual task). In Experiment 1, the fixed-attribute change (colour or position) occurred 0, 250, 500 or 1000 ms following the end of the motor action or the presentation of an auditory cue, while the variable-attribute change (position or colour) occurred randomly within an interval of ±200 ms from the fixed-attribute change. In Experiment 2, the visual stimulus was presented at a distance of 0, 2, 4 or 8 cm from a central fixation cross which was the target in the motor task. The fixed attribute (colour or position) changed 700 ms after an auditory cue (perceptual task) or when the hand reached the visual target (motor task). The variable-attribute change (position or colour) again occurred within an interval of ±200 ms from the fixed-attribute change. Statistical analysis of the point of subjective simultaneity revealed that performing a motor action reduced the perceived temporal asynchrony in the perceptual task, but only when the visual changes occurred less than 500 ms (for the fixed attribute) following movement execution (Exp. 1) and at a distance of less than 4 cm from the movement endpoint (Exp. 2). These results indicate that action-induced sensory binding requires temporal contiguity and spatial congruency between the endpoint of the action and its visual consequences.