| Résumé | Introduction: If an individual is engaged in a visual task, the onset of a highly novel but unattended auditory stimulus may result in a switch of attention away from the processing of the task-at-hand and to the processing of the more potentially relevant auditory stimuli. This switch is called attention capture. An auditory deviant, representing a change to any feature of a frequently occurring standard stimulus, will automatically elicit an event-related potential, the deviant-related negativity (DRN). If the deviant is highly novel, it may also elicit a later positivity, the P3a, associated with the switching of attention. There is some evidence that carrying out a visual working memory (WM) task may reduce the extent of attention capture. Also, individuals carrying out a task within a virtual reality (VR) environment often report that they may not be aware of irrelevant external stimuli occurring in the external environment that might otherwise elicit attention capture.
Methods: Nineteen young adults were engaged in three visual tasks: watching a silent video (control), performing a delayed match-to-sample WM task in a VR environment and performing a somewhat similar WM task presented on a 2D monitor. A multi-feature auditory sequence was presented concurrently but this was irrelevant to the visual task and was to-be-ignored. The sequence consisted of a frequently occurring standard stimulus and six different rarely occurring deviants, created by changing a different feature of the standard.
Results: All unattended auditory deviants elicited a significant DRN, reflecting robust automatic detection of auditory change. The nature of the visual task had no significant effect on the DRN. Only highly novel deviants (white noise, environmental sounds) elicited a P3a when participants watched the video. This P3a was significantly reduced during both the VR WM and 2D WM tasks.
Discussion: These findings suggest that early processes associated with detection of acoustic change operate automatically, regardless of the demands of the visual task. On the other hand, the P3a, associated with attention-capture and the switching of attention from the task-at-hand, was reduced in the VR a WM task. It was, however, also reduced in the 2D WM task. It is thus not clear whether the VR environment or the fact that participants were engaged in a WM task was responsible for the reduction of the P3a. |
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