We studied whether visual search for targets defined by a combination of features from different dimensions is guided by separately represented target features or by an integrated representation of the target objects. In Experiment 1, participants searched for target singleton bars that were defined by a specific combination of color (red or blue) and size (small or large). The target arrays were preceded by cue arrays that contained a spatially uninformative color/size singleton. Behavioral spatial-cueing effects indicative of attentional capture were triggered only by cues that matched both target-defining features, but not by partially target-matching cues, suggesting that attention was guided by integrated object representations. However, the presence of reliable N2pc components for partially matching cues demonstrated that these cues did capture attention, in line with independent feature-based guidance of attention. This dissociation between the electrophysiological and behavioral markers of attentional capture was confirmed in Experiment 2, in which targets were defined by a color/size disjunction. Our results suggest that the attentional selection of targets that are defined by a combination of features is a two-stage process: Attention is initially captured by all target-matching features, but is then rapidly withdrawn from nontarget objects that share some but not all features with the current target.

Although it is well established that prior experience with faces determines their subsequent social-emotional evaluation, recent work shows that top-down inhibitory mechanisms, including response inhibition, can lead to social devaluation after even a single, brief exposure. These rapidly induced effects indicate interplay among perceptual, attentional, response-selection and social-emotional networks; yet, the brain mechanisms underlying this are not well understood. This study used functional magnetic resonance imaging (fMRI) to investigate the neural mechanism mediating the relationship between inhibitory control and emotional devaluation. Participants performed two tasks: (i) a Go/No-Go task in response to faces and (ii) a trustworthiness rating task involving the previously seen faces. No-Go faces were rated as significantly less trustworthy than Go faces. By examining brain activations during Task 1, behavioral measures and brain activations obtained in Task 2 could be predicted. Specifically, activity in brain areas during Task 1 associated with (i) executive control and response suppression (i.e. lateral prefrontal cortex) and (ii) affective responses and value representation (i.e. orbitofrontal cortex), systematically covaried with behavioral ratings and amygdala activity obtained during Task 2. The present findings offer insights into the neural mechanisms linking inhibitory processes to affective responses.

A doktori ertekezesem celja, hogy szeleskorű kitekintessel mutassa be a kozmeghallgatas helyi onkormanyzati jogintezmenyenek magyar es nemzetkozi modelljeit, fejlődesi iranyait, valamint a hatalyos normativ es helyi onkormanyzati szabalyozasok alapulvetelevel ertekelje a jogintezmeny elmeleti kerdeseit, gyakorlati megvalosulasat, es megallapitsa a helyi onkormanyzas gyakorlataban is hasznosithato tudomanyos konkluziokat, javaslatokat.

When target-defining features are specified in advance, attentional target selection in visual search is controlled by preparatory top-down task sets. We used ERP measures to study voluntary target selection in the absence of such feature-specific task sets, and to compare it to selection that is guided by advance knowledge about target features. Visual search arrays contained two different color singleton digits, and participants had to select one of these as target and report its parity. Target color was either known in advance (fixed color task) or had to be selected anew on each trial (free color-choice task). ERP correlates of spatially selective attentional target selection (N2pc) and working memory processing (SPCN) demonstrated rapid target selection and efficient exclusion of color singleton distractors from focal attention and working memory in the fixed color task. In the free color-choice task, spatially selective processing also emerged rapidly, but selection efficiency was reduced, with nontarget singleton digits capturing attention and gaining access to working memory. Results demonstrate the benefits of top-down task sets: Feature-specific advance preparation accelerates target selection, rapidly resolves attentional competition, and prevents irrelevant events from attracting attention and entering working memory.

The question whether attentional capture by salient visual stimuli is driven by bottom-up salience or is contingent on top-down task set is still under dispute. We show that the ability of size singletons to capture attention is determined by current search goals. Participants searched for small or large target singletons among medium-size distractors. Attentional capture by small or large size singleton cues that preceded target search displays was reflected by spatial cueing effects and N2pc components. These effects were observed only when these cues matched the current target-defining feature, but not for physically identical but mismatching cues. Results demonstrate that attentional capture by size singletons is not driven by bottom-up salience, but is controlled by feature-specific task settings.

The question whether attentional capture by salient but task-irrelevant visual stimuli is triggered in a bottom-up fashion or depends on top-down task settings is still unresolved. Strong support for bottom-up capture was obtained in the additional singleton task, in which search arrays were visible until response onset. Equally strong evidence for top-down control of attentional capture was obtained in spatial cueing experiments in which display durations were very brief. To demonstrate the critical role of temporal task demands on salience-driven attentional capture, we measured ERP indicators of capture by task-irrelevant color singletons in search arrays that could also contain a shape target. In Experiment 1, all displays were visible until response onset. In Experiment 2, display duration was limited to 200 msec. With long display durations, color singleton distractors elicited an N2pc component that was followed by a late Pd component, suggesting that they triggered attentional capture, which was later replaced by location-specific inhibition. When search arrays were visible for only 200 msec, the distractor-elicited N2pc was eliminated and was replaced by a Pd component in the same time range, indicative of rapid suppression of capture. Results show that attentional capture by salient distractors can be inhibited for short-duration search displays, in which it would interfere with target processing. They demonstrate that salience-driven capture is not a purely bottom-up phenomenon but is subject to top-down control.

Salient visual singleton stimuli produce spatial cueing effects indicative of attentional capture only when they match current task sets, suggesting that capture is subject to top-down control. However, such task-set contingent capture effects could be associated with the top-down controlled disengagement of attention from non-matching stimuli that follows their initial bottom-up salience-driven selection. Using the N2pc component as an event-related potential marker of attentional capture, we demonstrate that top-down task set already controls the initial rapid selection of salient visual singleton stimuli prior to any subsequent attentional disengagement. These findings provide new evidence for the primacy of top-down control over bottom-up salience in attentional capture.

A neural adaptation paradigm where adaptor and test stimuli were presented in rapid succession was employed to investigate links between the face-sensitive N170 component and configural face processing. In Experiment 1, schematic adaptor stimuli preceded naturalistic images of upright faces, inverted faces, or isolated eyes. Relative to a baseline condition with schematic house adaptors, upright and inverted schematic faces adapted the N170 to subsequent naturalistic faces, demonstrating that this component is associated with neural processes involved in the analysis of first-order relational face configuration. In Experiment 2, two-tone Mooney faces adapted the N170 to naturalistic faces relative to a baseline condition with Mooney houses, suggesting links between the N170 and holistic face processing. Results demonstrate that the N170 component does not exclusively reflect the detection and analysis of individual face parts, but also the processing of first-order configural and global gestalt features of faces. They also show that neural adaptation procedures can be used to identify the neural mechanisms that are responsible for category-specific ERP components such as the N170.

We investigated whether the absence of one item in a regularly spaced visual array (gap cue) captures attention in a task-set-independent fashion. Participants searched for a large target among medium-size distractors (size task) or a red target among gray distractors (color task). Target arrays were preceded by uninformative cue arrays that contained a color singleton or a gap cue. The N2pc component was measured as an index of attentional capture. Color singleton cues captured attention only in the color task, but gap cues captured attention in both tasks. For cue arrays containing a color singleton and a gap cue on opposite sides, an N2pc was triggered by the color singleton in the color task. The absence of an item in a regular array triggered task-set-independent attentional capture when it was the only unique display feature, but not when a competing set-matching singleton was simultaneously present.

To investigate how target detection in visual search is modulated when a subset of distractors is presented in advance (preview search), we measured search performance and the N2pc component as an electrophysiological marker of attentional target selection. Targets defined by a color/shape conjunction were detected faster and the N2pc emerged earlier in preview search relative to a condition in which all items were presented simultaneously. Behavioral and electrophysiological preview benefits disappeared when stimuli were equiluminant with their background, in spite of the fact that targets were feature singletons among the new items in preview search. The results demonstrate that previewing distractors expedites the spatial selection of targets at early sensory-perceptual stages, and that these preview benefits depend on rapid attentional capture by luminance onsets.

Is the spatial selection of visual objects fully under the control of top-down factors such as current tasks sets? In his admirably clear and systematic review (Theeuwes, 2010), Jan Theeuwes claims that the selection of visual objects is determined solely by bottom-up mechanisms that are independent of observers' selection intentions, and that top-down control only comes into play at later stages of attentional processing. His argument starts with the assumption that visual information is initially processed in a parallel and feedforward fashion, and that this early stage is entirely stimulus-driven. That much is not contentious — in fact, many models of visual processing and attentional selectivity assume the existence of an early fast feedforward sweep that is essentially non-selective. Theeuwes' central and controversial claim concerns the factors that drive the subsequent attentional selection of visual objects. He argues that this selection is determined by bottom-up salience maps that are computed during the initial parallel visual processing stage. Crucially, this salience-driven attentional object selection cannot be prevented or even modulated by top-down task set. Top-down factors can only influence what happens after an object has been selected; for example, attention can be rapidly disengaged from objects that do not possess currently task-relevant attributes. But intentional factors have no role whatsoever in the attentional selection of visual objects. It is unusual to define a psychological concept (bottom-up visual selection) by applying a negative criterion (the absence of intentional modulation). As a result, there is a surprisingly wide range of cases that appear to meet this criterion. For example, Theeuwes considers phenomena such as intertrial feature priming or memory-driven attentional capture to be instances of bottom-up selection, even though here the selection of visual objects is not determined by their salience. Such an extension of the concept of bottom-up selection

To investigate how attentional capture in visual search is affected by generalized top-down search strategies, ERPs and behavioral performance were measured in two experiments where spatially nonpredictive color singleton cues preceded visual search arrays that contained one of two equally likely color singletons. When both singletons served as targets, irrelevant-color singleton cues produced behavioral attentional capture effects and elicited an N2pc component, indicative of a singleton search mode. When responses were required to only one of the two color singletons, the same cues no longer elicited behavioral spatial cuing effects, and the N2pc to these cues was attenuated and delayed, in line with the hypothesis that search was now guided by a feature-specific search strategy. Results demonstrate that the ability of visual singleton stimuli to capture attention is not simply determined by their bottom-up salience, but strongly modulated by top-down task sets.

To study the response profile of the face-selective N170 component, an adaptation procedure was employed where adaptor and test stimuli were presented in rapid succession. Test stimuli came from 4 different face categories (upright, inverted, and eyeless faces and eyes-only images). The same face stimuli, as well as upright and inverted houses, served as adaptors. Strong N170 amplitude reductions indicative of adaptation were found for all types of face test stimuli preceded by face adaptors relative to house adaptors, demonstrating that at a generic level, the N170 reflects the activation of face-selective neurons by full faces and by face parts. The highly specific pattern of N170 adaptation effects for different combinations of adaptor and test stimulus categories suggests additional distinct contributions of eye-selective neurons and of face-sensitive neurons that are tuned to deviations from canonical stimulus orientations to the N170 component. Results demonstrate that the N170 is generated by multiple neural sources at both early and later stages of configural face processing and that rapid adaptation techniques provide a powerful tool to dissociate these sources.

Previous research has demonstrated that the maintenance of visual information in working memory is associated with a sustained posterior contralateral negativity. Here we show that this component is also elicited during the spatially selective access to visual working memory. Participants memorized a bilateral visual search array that contained two potential targets on the left and right side. The task-relevant side was signalled by post-cues that were presented either 150 ms after array offset or after a longer interval (700-1000 ms). Enhanced negativities at posterior electrodes contralateral to the cued side of a target were elicited in response to both early and late post-cues, suggesting that they reflect not only memory maintenance, but also processes involved in the access to stored visual working memory representations. Results provide new electrophysiological evidence for the retinotopic organization of visual working memory.

Previous behavioural studies have shown that the repetition of target or distractor features across trials speeds pop-out visual search. We obtained behavioural and event-related brain potential (ERP) measures in two experiments where participants searched for a colour singleton target among homogeneously coloured distractors. An ERP marker of spatially selective attention (N2pc component) was delayed when either target or distractor colours were swapped across successive trials, demonstrating that intertrial feature priming systematically affects the onset of focal-attentional target processing. Results support the hypothesis that priming of pop-out effects are primarily generated at early perceptual/attentional stages of visual processing.