Disruption of cognitive performance by sound : Differentiating two forms of auditory distraction

Attentional selectivity—the capacity to focus on task-relevant events and ignore effectively task-irrelevant events—is a core feature of all efficient information processing. In order to be maximally efficient, attention must be flexible so that it can be responsive to unexpected and potentially significant events outside the focus of attention. Flexibility is achieved by having a degree of processing of events that are at any one time outside the attentional focus. This is only achieved at some cost, however, both from the need to monitor events but also because such events have the potential to wrest attention away from task-relevant processing even when they are not in fact of interest or importance. Attentional control—which is essentially about mapping of events in the world onto one of a range of possible actions— cannot be completely efficient. Indeed, in the auditory modality there is evidence that all auditory information is processed in an obligatory fashion, making behaviour particularly liable to distraction by sound. A range of findings reviewed here suggest that this obligatory processing of sound can lead to two distinct forms of auditory distraction. The first—competitionfor-action—occurs when the results of obligatory sound processing are similar to those of the focal task. The second—interruption-of-action—takes place when an unexpected sound draws attention away from the focal activity. In this paper, we focus on reviewing four lines of recent evidence that suggest that the two forms of distraction are distinct, namely: i) that the two forms act additively; as well as differences in the expression of each according to ii) the type of focal task; iii) the attentional load involved in stimulus-encoding; and iv) whether the focal information is being taken in or whether it is being acted-upon. We first provide an overview of each form of distraction.