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Capture by context elements, not attentional suppression of distractors, explains the PD with small search displays by Dirk Kerzel & Nicolas Burra

According to the threat-capture hypothesis, fear-related stimuli have a high attentional priority. As a result, irrelevant-but-salient stimuli interfere more with a visual search task when they are perceived as threatening. We investigated the neural basis for behavioral interference in conditions that promote attentional suppression of distracting stimuli (i.e., easy search with fixed target/distractor roles). In Experiment 1, participants discriminated the shape of a neutral target (a flower), which competed for selection with a threat-related (spider) or neutral (leaf) distractor. In line with prior results, we observed larger interference from spider than leaf distractors. At an electrophysiological level, we found that participants actively suppressed both distractors as evidenced by the presence of a posterior positivity between 200-300 ms, the PD. Critically, the PD was delayed with spider compared to leaf distractors. Further, in the spider distractor condition, the offset of the PD component correlated with response time to complete the search task when the spider was present. Experiment 2 was a control experiment where we confirmed that the results depended on the execution of the peripheral search task. When participants performed a localization task on the fixation cross, the decisive results from Experiment 1 were not replicated despite equal peripheral stimulation. Our results indicate that the behavioral delay incurred by threatening stimuli is accompanied by a delay of suppressive mechanisms. In contrast, we found no evidence for initial capture followed by suppression that may be predicted by hypervigilance-avoidance theory.

Salient vocalizations, especially aggressive voices, are believed to attract attention due to an automatic threat detection system. However, studies assessing the temporal dynamics of auditory spatial attention to aggressive voices are missing. Using event-related potential markers of auditory spatial attention (N2ac and LPCpc), we show that attentional processing of threatening vocal signals is enhanced at two different stages of auditory processing. As early as 200 ms post stimulus onset, attentional orienting/engagement is enhanced for threatening as compared to happy vocal signals. Subsequently, as early as 400 ms post stimulus onset, the reorienting of auditory attention to the center of the screen (or disengagement from the target) is enhanced. This latter effect is consistent with the need to optimize perception by balancing the intake of stimulation from left and right auditory space. Our results extend the scope of theories from the visual to the auditory modality by showing that threatening stimuli also bias early spatial attention in the auditory modality. Although not the focus of the present work, we observed that the attentional enhancement was more pronounced in female than male participants.

We investigated the effects of task demands and individual differences on the allocation of attention. Using the same stimuli, participants indicated the orientation of a line contained in a shape singleton (identification task) or the presence of singletons (detection task). Shape singletons in the identification task elicited a contralateral negativity (N2pc) whereas shape singletons in the detection task elicited a contralateral positivity (Pd). We suggest that the reduction of attentional priority of a salient stimulus, reflected by the Pd, occurred more rapidly with the less demanding detection task. Further, fewer distractible participants showed a larger N2pc to lateral color distractors than highly distractible participants. We suggest that highly distractible participants developed compensatory mechanisms to suppress distracting stimuli.

Notre déploiement attentionnel lors de tâche de recherche visuelle est ralenti par la présence d'un stimulus saillant non-pertinent pour la tâche. Ceci plaide pour une priorité des processus descendants sur les processus ascendants. La capture attentionnelle étant un processus précoce, nous avons décidé d'enquêter sur ce processus en utilisant l'électrophysiologie et plus précisément, un potentiel évoqué latéralisé appelé N2pc. Nous avons pu montré que la N2pc pour le distracteur était modulé par l'imprévisibilté de la cible. En outre, nous avons constaté une forte corrélation entre l'amplitude de la N2pc au distracteur et le niveau de distraction, mesurée par un questionnaire d'auto — évaluation (« Cognitive Failure Questionnaire »). De plus, nous avons démontré que lorsque la tâche ne necssite pas une identification claire d'une cible, une N2pc peut être remplacé par une positivité au distracteur. En résumé, ces données impliquent que la capture attentionelle est modulé par les processus descendant.