Attention capture by novel sounds: Distraction versus facilitation

Unexpected sounds have been shown to capture attention, triggering an orienting response. However, opposing effects of this attention capture on the performance of a concomitant visual task have been reported, in some instances leading to distraction and in others to facilitation. Moreover, the orienting response towards the unexpected stimuli can be modulated by working memory (WM) load, but the direction of this modulation has been another issue of controversy. In four experiments, we aimed to establish the critical factors that determine whether novel sounds facilitate or disrupt task performance and the modulation of these effects by WM load. Depending on the overall attentional demands of the task, novel sounds led to faster or slower responses. WM load attenuated novel sound effects, independent of their direction (facilitation or distraction). We propose a model by which the unexpected stimuli always generate the same orienting response but result in distraction or facilitation depending critically on the attentional focusing induced by the task at hand and the temporal relationship between the irrelevant and task-related stimuli.