Independent, synchronous access to color and motion features.

We investigated the role of attention in pairing superimposed visual features. When moving dots alternate in color and in motion direction, reports of the perceived color and motion reveal an asynchrony: the most accurate reports occur when the motion change precedes the associated color change by approximately 100ms [Moutoussis, K., & Zeki, S. (1997). A direct demonstration of perceptual asynchrony in vision. Proceedings of the Royal Society of London B, 264, 393-399]. This feature binding asynchrony was probed by manipulating endogenous and exogenous attention. First, endogenous attention was manipulated by changing which feature dimension observers were instructed to attend to first. This yielded little effect on the asynchrony. Second, exogenous attention was manipulated by briefly presenting a ring around the target, cueing the report of the color and motion seen within the ring. This reduced or eliminated the apparent latency difference between color and motion. Accuracy was best predicted by timing of each feature relative to the cue rather than the timing of the two features relative to each other, suggesting independent attentional access to the two features with an exogenous attention cue. The timing of attentional cueing affected feature pairing reports as much as the timing of the features themselves.