Tracking the Location of Visuospatial Attention in a Contingent Capture Paradigm

Abstract

Currently, there is considerable controversy regarding the degree to which top-down control can affect attentional capture by salient events. According to the contingent capture hypothesis, attentional capture by a salient stimulus is contingent on a match between the properties of the stimulus and top-down attentional control settings. In contrast, bottom-up saliency accounts argue that the initial capture of attention is determined solely by the relative salience of the stimulus, and the effect of top-down attentional control is limited to effects on the duration of attentional engagement on the capturing stimulus. In the present study, we tested these competing accounts by utilizing the N2pc event-related potential component to track the locus of attention during an attentional capture task. The results were completely consistent with the contingent capture hypothesis: An N2pc wave was elicited only by distractors that possessed the target-defining attribute. In a second experiment, we expanded upon this finding by exploring the effect of target-distractor similarity on the duration that attention dwells at the distractor location. In this experiment, only distractors possessing the target-defining attribute (color) captured visuospatial attention to their location and the N2pc increased in duration and in magnitude when the capture distractor also shared a second target attribute (category membership). Finally, in three additional control experiments, we replicated the finding of an N2pc generated by distractors, only if they shared the target-defining attribute. Thus, our results demonstrate that attentional control settings influence both which stimuli attract attention and to what extent they are processed.

Task relevance effects in electrophysiological brain activity: Early, but not first

“…The contrasting view is that stimulus features that are contingent with a current behavioural goal (e.g., redness when the target is red) have an effect on these early processing stages (Folk and Remington, 2006). Based on this position we predicted that relevance factors (e.g., distracter-target contingency) affect early ERP components simultaneously or even prior to visual saliency (e.g., luminance contrast) (Leblanc et al, 2008).…”

“…For example, Eimer and Kiss (2010)) found that a task-relevant, spatially uninformative cue modulated ERPs in the time-window 180-280 ms after cue onset. Using a rapid serial visual presentation task Leblanc et al (2008) found that lateral flankers sharing a critical property with the target interfered with target detection. Similar to the findings of Kiss (2008, 2010) this effect was accompanied by a modulation of the N2pc, an ERP component related to contralateral shifts of attention (Luck and Hillyard, 1994).…”

“…In contrast, other studies using similar paradigms found that stimulus relevance is a crucial determinant of attentional capture and may affect early cortical processing of visual stimuli (Eimer and Kiss, 2008;Leblanc et al, 2008;Ptak et al, 2011;Yantis and Egeth, 1999). For instance, the capture of attention by goal-relevant features modulates event-related potentials (ERPs) approximately 180 ms after stimulus onset (Leblanc et al, 2008). However, these studies aimed to show that relevant stimulus features influence early brain activity; therefore, the saliency of stimuli was kept constant, precluding the observation of competitive or interactive effects between bottom-up and top-down processes.…”

“…An argument put forward to favour this proposal is the observation that irrelevant distracters with a unique feature capture attention (Jonides and Yantis, 1988) or gaze (Theeuwes et al, 1999;van Zoest et al, 2004) and elicit electrophysiological responses preceding activity related to processing of the relevant target (Hickey et al, 2006). In contrast, other studies using similar paradigms found that stimulus relevance is a crucial determinant of attentional capture and may affect early cortical processing of visual stimuli (Eimer and Kiss, 2008;Leblanc et al, 2008;Ptak et al, 2011;Yantis and Egeth, 1999). For instance, the capture of attention by goal-relevant features modulates event-related potentials (ERPs) approximately 180 ms after stimulus onset (Leblanc et al, 2008).…”

All set, indeed! N2pc components reveal simultaneous attentional control settings for multiple target colors.

“…Previous ERP studies of task-set contingent attentional capture have demonstrated that the N2pc can be used to measure currently active topdown attentional control settings. During search for a specific target feature, task-set matching colour singleton cues (e.g., red singleton cues during search for red targets) triggered an N2pc, but nonmatching cues did not (e.g., red singleton cues during search for blue targets or small targets; e.g., Eimer & Kiss, 2008;Lien, Ruthruff, Goodin, & Remington, 2008;Leblanc, Prime, & Jolicoeur, 2008;Eimer, Kiss, Press, & Sauter, 2009). The presence of an N2pc to target-matching cues shows that these cues capture attention at a relatively early stage of visual-perceptual processing, while the absence of an N2pc to nonmatching cues indicates that their features fail to capture attention because they are not part of the currently active task set.…”