Auditory cues for attention management

An exhaustible supply of mental resources necessitate that we are selective for what we attend to. Attention prioritizes what ought to be processed and what ignored, allocating valuable resources to selected information at the cost of unattended information elsewhere. For this purpose it is necessary to know the conditions that help the brain decide when attention should be paid, where to and to what information. The question that is central to this dissertation is how auditory cues can support the management of limited attentional resources based on auditory characteristics. Auditory cues can (1) increase the overall alertness, (2) orient attention to unattended information, or (3) manage attentional resources by informing of an upcoming task-switch and, therefore, indicate when to pay attention to which task. The first study of this dissertation investigated whether different population groups might process auditory cues differently, thus resulting in different levels of alertness (1). Study two examined more specifically whether the type of auditory cue (verbal command or auditory icon) used as in-vehicle notifications can influence the level of alertness (1). Studies three and four investigated the use of a special auditory cue characteristic, the looming intensity profile, for directing attention to regions of interest (2). Here, attention orienting to peripheral events was tested within a dual-task paradigm which required attention shifts between the two tasks (3). Throughout the studies, I show that electroencephalography (EEG) is an indispensable tool for evaluating auditory cues and their influence on crossmodal attention. By using EEG measurements, I was able to demonstrate that auditory cues evoked the same level of alertness across different populations and that differences in behavioral responses are not due to subjective differences of cue processing (Chapter 2). More importantly, I was able to show that verbal commands and auditory cues can be functionally discriminated by the brain. While both sounds are alerting they ought to be used complementary, depending on the intended goal (Chapter 3). The studies that employed the looming sound to redirect spatial attention to an unattended visual target showed a robust benefit in response times at longer cue-target intervals (Chapter 4 and 5). The looming benefit in processing visual targets is also apparent as enhanced neural activity in the right posterior hemisphere 280ms after target onset. Source-estimation results suggest that a preferential activation of frontal and parietal areas, which are involved in attention orienting, give rise to this looming benefit (Chapter 5). Finally, auditory cues improved performance for unattended targets but might also benefit the central visuo-motor task by only directing attention to the periphery without moving the eyes away from the visuo-motor task. This demonstrates that auditory cues also help in managing attention by preparing for task switches such that covert attention is allocated to the respective task when this task has to be performed. Overall this dissertation demonstrates that the careful selection of auditory cues can go a long way in supporting attention management

The time course of auditory looming cues in redirecting visuo-spatial attention

Abstract By orienting attention, auditory cues can improve the discrimination of spatially congruent visual targets. Looming sounds that increase in intensity are processed preferentially by the brain. Thus, we investigated whether auditory looming cues can orient visuo-spatial attention more effectively than static and receding sounds. Specifically, different auditory cues could redirect attention away from a continuous central visuo-motor tracking task to peripheral visual targets that appeared occasionally. To investigate the time course of crossmodal cuing, Experiment 1 presented visual targets at different time-points across a 500 ms auditory cue’s presentation. No benefits were found for simultaneous audio-visual cue-target presentation. The largest crossmodal benefit occurred at early cue-target asynchrony onsets (i.e., CTOA = 250 ms), regardless of auditory cue type, which diminished at CTOA = 500 ms for static and receding cues. However, auditory looming cues showed a late crossmodal cuing benefit at CTOA = 500 ms. Experiment 2 showed that this late auditory looming cue benefit was independent of the cue’s intensity when the visual target appeared. Thus, we conclude that the late crossmodal benefit throughout an auditory looming cue’s presentation is due to its increasing intensity profile. The neural basis for this benefit and its ecological implications are discussed