Polly Dalton

Auditory Attentional Capture: Effects of Singleton Distractor Sounds

The phenomenon of attentional capture by a unique yet irrelevant singleton distractor has typically been studied in visual search. In this article, the authors examine whether a similar phenomenon occurs in the auditory domain. 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 establish the phenomenon of auditory attentional capture.

The role of working memory in auditory selective attention.

A growing body of research now demonstrates that working memory plays an important role in controlling the extent to which irrelevant visual distractors are processed during visual selective attention tasks (e.g., Lavie, Hirst, De Fockert, & Viding, 2004). Recently, it has been shown that the successful selection of tactile information also depends on the availability of working memory (Dalton, Lavie, & Spence, 2009). Here, we investigate whether working memory plays a role in auditory selective attention. Participants focused their attention on short continuous bursts of white noise (targets) while attempting to ignore pulsed bursts of noise (distractors). Distractor interference in this auditory task, as measured in terms of the difference in performance between congruent and incongruent distractor trials, increased significantly under high (vs. low) load in a concurrent working-memory task. These results provide the first evidence demonstrating a causal role for working memory in reducing interference by irrelevant auditory distractors.

Response requirements modulate tactile spatial congruency effects

Several recent studies have provided support for the view that tactile stimuli/events are remapped into an abstract spatial frame of reference beyond the initial somatotopic representation present in the primary somatosensory cortex. Here, we demonstrate for the first time that the extent to which this remapping of tactile stimuli takes place is dependent upon the particular demands imposed by the task that participants have to perform. Participants in the present study responded to either the elevation (up vs. down) or to the anatomical location (finger vs. thumb) of vibrotactile targets presented to one hand, while trying to ignore distractors presented simultaneously to the other hand. The magnitude and direction of the target–distractor congruency effect was measured as participants adopted one of two different postures with each hand (palm-up or palm-down). When the participants used footpedal responses (toe vs. heel; Experiment 1), congruency effects were determined by the relative elevation of the stimuli in external coordinates (same vs. different elevation), regardless of whether the relevant response feature was defined externally or anatomically. Even when participants responded verbally (Experiment 2), the influence of the relative elevation of the stimuli in external space, albeit attenuated, was still observed. However, when the task involved responding with the stimulated finger (four-alternative forced choice; Experiment 3), congruency effects were virtually eliminated. These findings support the view that tactile events can be remapped according to an abstract frame of reference resulting from multisensory integration, but that the frame of reference that is used while performing a particular task may depend to a large extent on the nature of the task demands.

Attentional capture in serial audiovisual search tasks

The phenomenon of attentional capture has typically been studied in spatial search tasks. Dalton and Lavie (2004) recently demonstrated that auditory attention can also be captured by a singleton item in a rapidly presented tone sequence. In the experiments reported here, we investigated whether these findings extend cross-modally to sequential search tasks using audiovisual stimuli. Participants searched a stream of centrally presented audiovisual stimuli for targets defined on a particular dimension (e.g., duration) in a particular modality. Task performance was compared in the presence versus absence of a unique singleton distractor. Irrelevant auditory singletons captured attention during visual search tasks, leading to interference when they coincided with distractors but to facilitation when they coincided with targets. These results demonstrate attentional capture by auditory singletons during nonspatial visual search.

The role of working memory in tactile selective attention

Load theory suggests that working memory controls the extent to which irrelevant distractors are processed (e.g., Lavie, Hirst, De Fockert, & Viding, 2004). However, so far this proposal has only been tested in vision. Here, we examine the extent to which tactile selective attention also depends on working memory. In Experiment 1, participants focused their attention on continuous target vibrations while attempting to ignore pulsed distractor vibrations. In Experiment 2, targets were always presented to a particular hand, with distractors being presented to the other hand. In both experiments, a high (vs. low) load in a concurrent working memory task led to greater interference by the tactile distractors. These results establish the role of working memory in the control of tactile selective attention, demonstrating for the first time that the principles of load theory also apply to the tactile modality.

Overriding auditory attentional capture

Attentional capture by color singletons during shape search can be eliminated when the target is not a feature singleton (Bacon & Egeth, 1994). This suggests that a “singleton detection” search strategy must be adopted for attentional capture to occur. Here we find similar effects on auditory attentional capture. Irrelevant highintensity singletons interfered with an auditory search task when the target itself was also a feature singleton. However, singleton interference was eliminated when the target was not a singleton (i.e., when nontargets were made heterogeneous, or when more than one target sound was presented). These results suggest that auditory attentional capture depends on the observer’s attentional set, as does visual attentional capture. The suggestion that hearing might act as an early warning system that would always be tuned to unexpected unique stimuli must therefore be modified to accommodate these strategy-dependent capture effects.

Temporal attentional capture: Effects of irrelevant singletons on rapid serial visual search

The presence of a unique yet irrelevantsingleton in visual search or spatial-cuing tasks is typically associated with performance costs, suggesting that singletons tend to capture attention. However, since singletons have always been spatially separated from targets in previous experiments, it remains unclear whether an irrelevant visual singleton that occurs at the same spatial location as the target but at a different point in time can produce temporal capture of attention. Here, we asked participants to search visual sequences at fixation for targets defined by size (larger or smaller than the nontargets). The presence (vs. absence) of a color singleton lengthened response times on the size discrimination task, suggesting that irrelevant singletons can lead to a temporal attentional capture.

Auditory attentional capture: implicit and explicit approaches

The extent to which distracting items capture attention despite being irrelevant to the task at hand can be measured either implicitly or explicitly (e.g., Simons, Trends Cogn Sci 4:147–155, 2000). Implicit approaches include the standard attentional capture paradigm in which distraction is measured in terms of reaction time and/or accuracy costs within a focal task in the presence (vs. absence) of a task-irrelevant distractor. Explicit measures include the inattention paradigm in which people are asked directly about their noticing of an unexpected task-irrelevant item. Although the processes of attentional capture have been studied extensively using both approaches in the visual domain, there is much less research on similar processes as they may operate within audition, and the research that does exist in the auditory domain has tended to focus exclusively on either an explicit or an implicit approach. This paper provides an overview of recent research on auditory attentional capture, integrating the key conclusions that may be drawn from both methodological approaches.

Out of touch? Visual load induces inattentional numbness

It is now well known that the absence of attention can leave people unaware of both visual and auditory stimuli (e.g., Dalton & Fraenkel, 2012; Mack & Rock, 1998). However, the possibility of similar effects within the tactile domain has received much less research. Here, we introduce a new tactile inattention paradigm and use it to test whether tactile awareness depends on the level of perceptual load in a concurrent visual task. Participants performed a visual search task of either low or high perceptual load, as well as responding to the presence or absence of a brief vibration delivered simultaneously to either the left or the right hand (50% of trials). Detection sensitivity to the clearly noticeable tactile stimulus was reduced under high (vs. low) visual perceptual load. These findings provide the first robust demonstration of “inattentional numbness,” as well as demonstrating that this phenomenon can be induced by concurrent visual perceptual load.

Driving with navigational instructions: Investigating user behaviour and performance

This paper reports the results of an inter-disciplinary study investigating user preferences and performance in relation to spoken in-car route guidance. In-car navigation systems are becoming increasingly popular. However, despite large amounts of research assessing the presentation of spatial information, and the usability and interaction issues surrounding the interfaces, there has been much less investigation of the impacts of auditory presentation of route information. We addressed this issue using a multi-disciplinary approach to collect both qualitative and quantitative data through questionnaires and user experiments. Our research identified a user preference for auditory presentation of route information, as well as a memory advantage for auditory over visual presentation. We also found that simple auditory route instructions could be followed without significant interference to a simulated driving task, whereas more complex auditory instructions did cause interference. Taken together, this research highlights the importance of the design of spoken route guidance instructions in minimising the cognitive demands that they impose.