The identity intrusion effect: Attentional capture or perceptual load?

Abstract

Theeuwes and Burger (1998) concluded that irrelevant colour singletons can capture attention within the context of a serial search task by showing that the identity of these singletons can intrude on target processing. However, other researchers have suggested that such distractor interference may arise from a passive, capacity-based selection mechanism that processes all display items automatically and in parallel across the visual field until attentional resources are consumed (Lavie, 1995). According to this perceptual load hypothesis, distractor interference should occur when perceptual load is low but not when perceptual load is high. The present study investigated whether the observed identity intrusion effect was due to attentional capture or perceptual load. Experiment 1 replicated the main findings reported by Theeuwes and Burger under conditions of relatively low perceptual load. Experiment 2 provided critical evidence for the perceptual load account by showing that the identity intrusion effect occurred in the context of low perceptual load, but not high perceptual load. The present findings were therefore interpreted to support the perceptual load account of the identity intrusion effect, not the attentional capture account.