Feature priming and the capture of visual attention: linking two ambiguity resolution hypotheses.

Visual search for a unique stimulus is often faster when the feature defining this target is repeated. Recent research has related this feature priming to ambiguity: priming effects appear stronger when the search target is perceptually ambiguous, as when the search array contains a salient distractor. Here we link the ambiguity that underlies feature priming to ambiguity in neural representation caused by the receptive field organization of visual cortex. We show that as the magnitude of neural activity involved in resolving perceptual ambiguity in early stages of visual cortex increases-indexed in posterior aspects of the N2pc component of the visual-event related potential--so does the behavioral feature priming effect. When ambiguity resolution mechanisms act strongly and the target repeats, target processing is facilitated. When these mechanisms act strongly, but the features that have previously defined the target come to characterize the distractor, attention is captured to the distractor location. These results suggest that ambiguity and the attentional mechanisms responsible for resolving it play central roles in feature priming.