Using a novel variant of dichotic selective listening, we examined the control of auditory selective attention. In our task, subjects had to respond selectively to one of two simultaneously presented auditory stimuli (number words), always spoken by a female and a male speaker, by performing a numerical size categorization. The gender of the task-relevant speaker could change, as indicated by a visual cue prior to auditory stimulus onset. Three experiments show clear performance costs with instructed attention switches. Experiment 2 varied the cuing interval to examine advance preparation for an attention switch. Experiment 3 additionally isolated auditory switch costs from visual cue priming by using two cues for each gender, so that gender repetition could be indicated by a changed cue. Experiment 2 showed that switch costs decreased with prolonged cuing intervals, but Experiment 3 revealed that preparation did not affect auditory switch costs but only visual cue priming. Moreover, incongruent numerical categories in competing auditory stimuli produced interference and substantially increased error rates, suggesting continued processing of task-relevant information that often leads to responding to the incorrect auditory source. Together, the data show clear limitations in advance preparation of auditory attention switches and suggest a considerable degree of inertia in intentional control of auditory selection criteria.

Using an auditory variant of task switching, we examined the ability to intentionally switch attention in a dichotic-listening task. In our study, participants responded selectively to one of two simultaneously presented auditory number words (spoken by a female and a male, one for each ear) by categorizing its numerical magnitude. The mapping of gender (female vs. male) and ear (left vs. right) was unpredictable. The to-be-attended feature for gender or ear, respectively, was indicated by a visual selection cue prior to auditory stimulus onset. In Experiment 1, explicitly cued switches of the relevant feature dimension (e.g., from gender to ear) and switches of the relevant feature within a dimension (e.g., from male to female) occurred in an unpredictable manner. We found large performance costs when the relevant feature switched, but switches of the relevant feature dimension incurred only small additional costs. The feature-switch costs were larger in ear-relevant than in gender-relevant trials. In Experiment 2, we replicated these findings using a simplified design (i.e., only within-dimension switches with blocked dimensions). In Experiment 3, we examined preparation effects by manipulating the cueing interval and found a preparation benefit only when ear was cued. Together, our data suggest that the large part of attentional switch costs arises from reconfiguration at the level of relevant auditory features (e.g., left vs. right) rather than feature dimensions (ear vs. gender). Additionally, our findings suggest that ear-based target selection benefits more from preparation time (i.e., time to direct attention to one ear) than gender-based target selection.

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In ap revious study the authors examined intentional switching in auditory selective attention using ad ichoticlistening paradigm. In the present study this paradigm wase xtended to more natural and realistic environments by changing it to ab inaural-listening paradigm in which human performance with different methods of spatial reproduction were compared. Four reproduction methods were used: real sources in an anechoic environment, individual binaural synthesis reproduced with headphones, non-individual binaural synthesis reproduced with headphones, and non-individual binaural synthesis reproduced with twol oudspeakers and Cross-Talk-Cancellation-Filters. Speech of twospeakers waspresented simultaneously to subjects from twoout of eight different directions. Guided by avisual cue, subjects were asked to categorize the target'sspeech while ignoring the distractor's speech. Results showed greater reaction times and error rates for non-individual repro duction methods. The influences of the spatial transition of the target-speaker (switch or repetition of speaker'sd irection in space)a nd of the spatial arrangement of the twospeakers were largely identical across reproduction methods, even though it wasg enerally easier to filter out distractor'ss peech when using real sources. The findings suggest that the reproduction methods can be usefully applied to study auditory attention with only very little loss in accuracy.

The aim of our study was to examine the role of task preparation and task inhibition in age-related task-switching deficits. In 2 experiments, we used a cuing paradigm with 3 tasks and manipulated the cue-stimulus interval (CSI). Additionally, switching among 3 tasks enabled us to examine n-2 task repetition costs, which reflect persisting inhibition of abandoned tasks. In Experiment 1, we found larger mixing costs (i.e., performance in mixed-task blocks vs. single-task blocks) in older adults than in young adults, and preparation effects were smaller in older adults than in young adults. In Experiment 2, where CSIs were blocked instead of randomly varied, we replicated reduced effects of task preparation in older adults. N-2 task repetition costs were not significant in Experiment 1 but significant in Experiment 2, and these costs did not differ across age groups in both experiments. The data suggest a task-preparation deficit in older adults that contributes to increased mixing costs in older adults.

Using a cued auditory task-switching variant of dichotic listening, we varied the response-cue interval (RCI) to examine temporal dissipation effects. On each trial, participants were presented with two different number words, one spoken by a female speaker and another by a male speaker (dichotic listening), that served as competing targets for a numerical judgment. The gender of the task-relevant speaker was indicated by a visual task cue prior to each trial. Experiment 1A used two different cues for each task (i.e., gender) and showed only small cue repetition benefits (same cue vs. alternate cue) but large auditory switch costs (alternate cue vs. task switch). A replication without immediate cue repetitions (Experiment 1B) showed very similar switch costs, suggesting that immediate cue repetitions play a negligible role for the size of auditory task switch costs. Moreover, switch costs were reduced when the (entirely task-irrelevant) location of the task-relevant speaker changed, relative to when it was unchanged, suggesting an episodic feature-binding component in our dichotic-listening task. Importantly, both experiments showed no effect of RCI on auditory switch costs. Because statistical power for this null effect was reasonably high across experiments (n = 50), this finding suggests that auditory attention settings do not dissipate quickly over time.

Using a task-switching variant of dichotic listening, we examined the ability to intentionally switch auditory attention between two speakers. We specifically focused on possible interactions with stimulus-response compatibility. In each trial, two words, one spoken by a male and another by a female, were presented dichotically via headphones. In one experimental group, two animal names were presented, and the relevant animal had to be judged as smaller or larger than a sheep by pressing a left or right response key. In another group, two number words were presented and had to be judged as smaller or larger than 5. In each trial, a visual cue indicated the gender of the relevant speaker. Performance was worse when the gender of the relevant speaker switched from trial to trial. These switch costs were larger for animal names than for number words, suggesting stronger interference with slower access to semantic categories. Responses were slower if the side of the target stimulus (as defined by the relevant gender) was spatially incompatible with the required response (as defined by the size judgment). This stimulus-response compatibility effect did not differ across stimulus material and did not interact with attentional switch costs. These results indicate that auditory switch costs and stimulus-response compatibility effects are dissociable, referring to target selection and response selection, respectively.

These data suggest that the ability to intentionally switch auditory attention in a selective listening task is not compromised in healthy aging. We discuss the role of modality-specific factors in age-related differences.