Tracking the misallocation and reallocation of spatial attention towards auditory stimuli.

Completely ignoring a salient distractor presented concurrently with a target is difficult and sometimes attention is involuntarily attracted to the distractor's location (attentional capture). Employing the N2ac component as a marker of attention allocation towards sounds, in this study we investigate the spatio-temporal dynamics of auditory attention across two experiments. Human participants (male and female) performed an auditory search task, where the target was accompanied by a distractor in 2/3rd of the trials. For a distractor more salient than target (Exp. 1), we observe not only a distractor N2ac (indicating attentional capture), but the full chain of attentional dynamics implied by the notion of attentional capture, namely: (a) the distractor captures attention before the target is attended, (b) allocation of attention to the target is delayed by distractor presence, and (c) the target is attended after the distractor. Conversely, for a distractor less salient than the target (Exp. 2), although responses were delayed, no attentional capture was observed. Together, these findings reveal two types of spatial-attentional dynamics in the auditory modality (distraction with and without attentional capture).Significance Statement Oftentimes, we find it hard to avoid attending to a salient sound that distracts us from our current tasks. Although, a common everyday experience, little is known about how spatial distraction unfolds at the neural level in the auditory modality. Using electrophysiological markers of attention allocations, we report comprehensive evidence of spatial attentional capture by a salient auditory distractor, indicating that attention is first misallocated to the distractor and only afterwards reallocated towards the target. Similar patterns were observed earlier only in vision and their discovery in the auditory modality indicates towards the existence of domain-general spatial attentional dynamics consistent across sensory modalities. We also demonstrate that only a distractor more salient than the target reliably captures attention.

Preparatory Control Against Distraction Is Not Feature-Based.

Salient-but-irrelevant stimuli (distractors) co-occurring with search targets can capture attention against the observer's will. Recently, evidence has accumulated that preparatory control can prevent this misguidance of spatial attention in predictable situations. However, the underlying mechanisms have remained elusive. Most pertinent theories assume that attention is guided by specific features. This widespread theoretical claim provides several strong predictions with regard to distractor handling that are disconfirmed here: Employing electrophysiological markers of covert attentional dynamics, in three experiments, we show that distractors standing out by a feature that is categorically different from the target consistently captures attention. However, equally salient distractors standing out in a different feature dimension are effectively down-weighted, even if unpredictably swapping their defining feature with the target. This shows that preparing for a distractor's feature is neither necessary nor sufficient for successful avoidance of attentional capture. Rather, capture is prevented by preparing for the distractor's feature dimension.

Intercommunication between prefrontal and posterior brain regions for protecting visual working memory from distractor interference.

Because visual working memory has a very restricted capacity, good filtering mechanisms are essential for its successful functioning. A neuronal signal emitted by the prefrontal cortex is considered to be an important contributor to filtering. Proof of the functional significance of this signal during normal cognitive functioning is, however, still missing. Furthermore, research has so far neglected that the prefrontal cortex must receive input from posterior brain areas that report the necessity to filter. From human electroencephalograms, we extracted several event-related components that reflect the different subprocesses of filtering. On the basis of their timing and a clear pattern of correlations, we reason that filtering might consist of a causal chain of events that involve prefrontal and posterior cortex regions: After distractors are detected in posterior regions, a prefrontal mechanism is activated, which in turn prevents subsequent unnecessary parietal storage of distractor information.

The surprising robustness of visual search against concurrent auditory distraction.

People often complain about distraction by irrelevant sounds that reportedly hamper performance on concurrent visual tasks demanding the allocation of focused attention toward relevant stimuli, such as processing street signs during driving. To study this everyday issue experimentally, we devised a cross-modal distraction paradigm, inspired by a standard visual-distraction paradigm (additional-singleton paradigm) that is highly sensitive to measure interference on the allocation of attention. In a visual-search pop-out task, participants reported whether a salient target (a tilted bar) was present or absent, while a completely irrelevant, but salient auditory distractor accompanied some trials. To our surprise, the results revealed no notable distraction on visual-search performance (controlled for speed-accuracy tradeoffs). Reliable auditory distraction failed to occur even when the distractor was a (highly salient) auditory oddball or was additionally presented with a temporal advantage of 300 ms. However, when the auditory modality was made relevant globally while maintaining its irrelevance to the visual-search task, we finally observed the expected interference effect. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Two good reasons to say 'change!' - ensemble representations as well as item representations impact standard measures of VWM capacity.

Visual working memory (VWM) is a central bottleneck in human information processing. Its capacity is most often measured in terms of how many individual-item representations VWM can hold (k). In the standard task employed to estimate k, an array of highly discriminable colour patches is maintained and, after a short retention interval, compared to a test display (change detection). Recent research has shown that with more complex, structured displays, change-detection performance is, in addition to individual-item representations, supported by ensemble representations formed as a result of spatial subgroupings. Here, by asking participants to additionally localize the change, we reveal indication for an influence of ensemble representations even in the very simple, unstructured displays of the colour-patch change-detection task. Critically, pure-item models from which standard formulae of k are derived do not consider ensemble representations and, therefore, potentially overestimate k. To gauge this overestimation, we develop an item-plus-ensemble model of change detection and change localization. Estimates of k from this new model are about 1 item (~30%) lower than the estimates from traditional pure-item models, even if derived from the same data sets.

Biasing Allocations of Attention via Selective Weighting of Saliency Signals: Behavioral and Neuroimaging Evidence for the Dimension-Weighting Account.

Objects that stand out from the environment tend to be of behavioral relevance, and the visual system is tuned to preferably process these salient objects by allocating focused attention. However, attention is not just passively (bottom-up) driven by stimulus features, but previous experiences and task goals exert strong biases toward attending or actively ignoring salient objects. The core and eponymous assumption of the dimension-weighting account (DWA) is that these top-down biases are not as flexible as one would like them to be; rather, they are subject to dimensional constraints. In particular, DWA assumes that people can often not search for objects that have a particular feature but only for objects that stand out from the environment (i.e., that are salient) in a particular feature dimension. We review behavioral and neuroimaging evidence for such dimensional constraints in three areas: search history, voluntary target enhancement, and distractor handling. The first two have been the focus of research on DWA since its inception and the latter the subject of our more recent research. Additionally, we discuss various challenges to the DWA and its relation to other prominent theories on top-down influences in visual search.

Recollection is delayed under changed viewing conditions: A graded effect on the latency of the late posterior component.

Object recognition is a central human ability. In everyday life, the conditions under which objects have to be recognized are usually not perfect. Often, viewing conditions change in between two encounters with an object; typical are changes in illumination or in the object-observer distance. With such changes, object recognition sometimes feels slightly delayed. We examined this phenomenon empirically by measuring the latency of the well-established electrophysiological correlate of recollection, the late posterior component (LPC), in an object-recognition task. Although the cognitive processes underlying successful recognition are well examined, thus far the consequences of changed viewing conditions on the timing of these processes have not been investigated. The ERP technique is well suited for investigating this question, because it allows differentiating between processes contributing to recognition times (in particular, recollection from familiarity as indexed by the FN400 component) and measuring their time course with high temporal precision. In the present study, participants' task was to differentiate previously studied (old) objects from a set of new objects. Viewing conditions for old objects changed slightly, changed strongly, or remained identical between learning and test. We found that the latency of the LPC in response to an old object was delayed whenever viewing conditions changed. Moreover, this delay in LPC latency scaled with the size of the change. These effects were absent for the FN400. This is the first examination of effects of changes in viewing conditions on the latency of recollection and the first dissociation of FN400 and LPC latencies.

ERP evidence for hemispheric asymmetries in abstract but not exemplar-specific repetition priming.

Implicit memory retrieval is thought to be exemplar-specific in the right hemisphere (RH) but abstract in the left hemisphere (LH). Yet, conflicting behavioral priming results illustrate that the level at which asymmetries take effect is difficult to pinpoint. In the present divided visual field experiment, we tried to address this issue by analyzing ERPs in addition to behavioral measures. Participants made a natural/artificial decision on lateralized visual objects that were either new, identical repetitions, or different exemplars of studied items. Hemispheric asymmetries did not emerge in either behavioral or late positive complex (LPC) priming effects, but did affect the process of implicit memory retrieval proper as indexed by an early frontal negativity (N350/(F)N400). Whereas exemplar-specific N350/(F)N400 priming effects emerged irrespective of presentation side, abstract implicit memory retrieval of different exemplars was contingent on right visual field presentation and the ensuing initial stimulus processing by the LH.