Attentional capture in hearing: Effects of irrelevant singleton sounds on auditory search.

The phenomenon of attentional capture by a unique yet irrelevant "singleton" distractor has typically been studied in visual search. In this thesis I ask whether attention can also be captured by auditory singletons in tasks of auditory search. Participants searched sequences of sounds for targets defined by frequency, intensity or duration. The presence of a "singleton" distractor that was unique on an irrelevant dimension (e.g. a low frequency singleton in search for a target of high intensity) was associated with search costs in both detection and discrimination tasks. However if the singleton feature coincided with the target item, search was facilitated. These results demonstrate attentional capture in the auditory domain. Further experiments showed that, like visual attentional capture, auditory attentional capture depends on participants adopting an "odd-one-out" strategy for attentional allocation. In addition, a final set of experiments confirmed that singleton interference could be found in tasks of visual sequential search, providing a direct visual analogue for the present auditory effects. Overall, this thesis establishes the phenomenon of auditory attentional capture, adding to a growing body of research demonstrating similarities between attentional processes in vision and hearing