Visual feature binding requires reentry.

Reentrant processing has been proposed as a critical mechanism in feature binding. To test this claim, participants were shown arrays of six pairs of crossed vertical and horizontal bars. In each pair, one bar was white; one was red, green, or blue. Identifying the orientation, but not the color, of the nonwhite bar in the target item required correct binding. Four dots appeared around one of the items (the target) and either disappeared with it or persisted for 300 ms after the array disappeared. This type of trailing mask is thought to interfere with target processing by disrupting reentry. Consistent with the hypothesis that binding requires reentrant processing, the trailing mask significantly reduced the accuracy of orientation but not color judgments. In a control condition, when the white bar was omitted, binding was no longer required, and both color and orientation were accurately reported.