Citation for published item:h¤ onhmmerD tFqF nd qruertD eF nd uerzelD hF nd fekerD FsF @PHITA 9ettentionl guidne y reltive fetures X ehviorl nd eletrophysiologil evideneF9D syhophysiologyFD SQ @UAF ppF IHUREIHVQF Further information on publisher's website: httpsXGGdoiForgGIHFIIIIGpsypFIPTRS Publisher's copyright statement: his is the epted version of the following rtileX h¤ onhmmerD tF qFD qruertD eFD uerzelD hF nd fekerD F sF @PHITAD ettentionl guidne y reltive feturesX fehviorl nd eletrophysiologil evideneF syhophysiologyD SQ@UAX IHUREIHVQD whih hs een pulished in (nl form t httpsXGGdoiForgGIHFIIIIGpsypFIPTRSF his rtile my e used for nonEommeril purposes in ordne ith iley erms nd gonditions for selfErhivingF Additional information: Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. Attentional guidance by relative features 2 Abstract Our ability to select task-relevant information from cluttered visual environments is widely believed to be due to our ability to tune attention to the particular elementary feature values of a sought-after target (e.g., red, orange, yellow). By contrast, recent findings showed that attention is often tuned to feature relationships, viz., features that the target has relative to irrelevant features in the context (e.g., redder, yellower; Becker, 2010). However, the evidence for such a relational account is so far exclusively based on behavioral measures that do not allow a safe inference about early perceptual processes. The present study provides a critical test of the relational account, by measuring an electrophysiological marker in the EEG of participants (N2pc) in response to briefly presented distractors (cues) that could either match the physical features of the target or its relative features. In a first experiment, the target color and non-target color was kept constant across trials. In line with a relational account, we found that only cues with the same relative color as the target were attended, regardless of whether the cues had the same physical color as the target. In a second experiment, we demonstrate that attention is biased to the exact target feature value when the target is embedded in a randomly varying context. Taken together, these results provide the first electrophysiological evidence that attention can modulate early perceptual processes differently; in a contextdependent manner vs. a context-independent manner, resulting in marked differences in the range of colors that can attract attention.Attentional guidance by relative features 3

Reaction times in a visual search task increase when an irrelevant but salient stimulus is presented. Recently, the hypothesis that the increase in reaction times was due to attentional capture by the salient distractor has been disputed. We devised a task in which a search display was shown after observers had initiated a reaching movement toward a touch screen. In a display of vertical bars, observers had to touch the oblique target while ignoring a salient color singleton. Because the hand was moving when the display appeared, reach trajectories revealed the current selection for action. We observed that salient but irrelevant stimuli changed the reach trajectory at the same time as the target was selected, about 270 ms after movement onset. The change in direction was corrected after another 160 ms. In a second experiment, we compared manual selection of color and orientation targets and observed that selection occurred earlier for color than for orientation targets. Salient stimuli support faster selection than do less salient stimuli. Under the assumption that attentional selection for action and perception are based on a common mechanism, our results suggest that attention is indeed captured by salient stimuli.

Recent attentional capture studies with the spatial cueing paradigm often found that target-dissimilar precues resulted in longer RTs on valid than invalid cue trials. These same location costs were accompanied by a contralateral positivity over posterior electrodes from 200 to 300 ms, similar to a P D component. Same location costs and the P D have been linked to the inhibition of cues with a unique feature (singleton cues) that do not match the target feature. In some studies reporting same location costs, the cue was surrounded by other cues (i.e., the context cues) that matched the physical or relative feature of the target. We hypothesized that the context cues might have captured attention and might have elicited data patterns that mimicked the inhibitory effects. To disentangle inhibition of the singleton cue from capture by the context cues, we added gray cues to the cue array, which we considered neutral because gray matched neither the target nor the nontarget color. In four experiments, the results consistently showed that the context cues in the nonmatching cue condition captured attention, as reflected in shorter RTs compared to neutral cues and a substantial N2pc to lateralized context cues. By contrast, the evidence for inhibition of the singleton cue was rather weak. Therefore, same location costs and lateralized positivity in the event-related potential of participants in several recent studies probably reflected attentional capture by the context cues, not inhibition of the singleton cue. Public Significance StatementHow do we select relevant information from cluttered visual scenes? Many studies suggest that attentional control mechanisms facilitate processing of relevant and inhibit processing of irrelevant information. Several recent studies found evidence that supports the inhibition of irrelevant information. This study shows, however, that in a subset of these studies the findings are more likely associated with facilitation of context information than with inhibition.

A salient stimulus may interrupt visual search because of attentional capture. It has been shown that attentional capture occurs with a wide, but not with a small attentional window. We tested the hypothesis that capture depends more strongly on the shape of the attentional window than on its size. Search elements were arranged in two nested rings. The ring containing the search target remained fixed, while a salient color singleton occurred either in the same or in the other ring. We observed that color singletons only disrupted search when shown in the same ring as the search target. It is important to note that, when focusing on the outer array, which presumably required a larger attentional window, singletons on the inner array did not capture attention. In contrast to the original attentional window hypothesis, our results show that attentional capture does not always occur with a large attentional window. Rather, attention can be flexibly allocated to the set of relevant stimulus locations and attentional capture is confined to the attended locations. Further experiments showed that attention was allocated to search elements that were perceptually grouped into "whole" or "Gestalt"-like objects, which prevented attentional capture from nearby locations. However, when attention was allocated to noncontiguous locations that did not form a perceptual Gestalt, nearby locations elicited attentional capture. Perceptual grouping could be based on a combination of color and position, but not on color alone. Thus, the allocation of attention to Gestalt-like objects that were jointly defined by similarity and proximity prevented attentional capture from nearby locations.

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