When a stimulus appears in a previously cued location several hundred milliseconds after the cue, the time required to detect that stimulus is greater than when it appears in an uncued location. This increase in detection time is known as inhibition of return (lOR). It has been suggested that lOR reflects the action of a general attentional mechanism that prevents attention from returning to previously explored loci. At the same time, the robustness of lOR has been recently disputed, given several failures to obtain the effect in tasks requiring discrimination rather than detection. In a series of eight experiments, we evaluated the differences between detection and discrimination tasks with regard to lOR. We found that lOR was consistently obtained with both tasks, although the temporal parameters required to observe lOR were different in detection and discrimination tasks. In our detection task, the effect appeared after a 400-msec delay between cue and target, and was still present after 1,300msec. In our discrimination task, the effect appeared later and disappeared sooner. The implications of these data for theoretical accounts of lOR are discussed.Attention is widely presumed to play an important role in the rapid and efficient scanning ofvisual environments. In particular, when search is difficult, the movement of attention from one location to another may improve discrimination at each location, and thus also improve overall search efficiency. However, the efficiency of search also depends on the ability to prevent attention from returning to previously examined locations. This issue has been the focus of considerable study by attention researchers over the past decade.Specifically, it has been shown that response to a target is speeded if the location at which the target appears is precued. In the cost-benefit paradigm (Posner, 1980), subjects are to respond to a target appearing in one of three boxes, one in the center ofthe screen and one to each side of the center. Before the target appears, the subject's attention is cued to one of the two peripheral locations. This attentional cuing is accomplished by making one of the two peripheral boxes flicker briefly. The target then appears in either the cued location (cued trials) or the uncued location (uncued trials). When the cue-target stimulus onset asynchrony (SOA) is less than about 300 msec, responses are faster on cued than on uncued trials.We thank Steven P. Tipper, Bruce Milliken, Arthur F. Kramer, an anonymous reviewer, and especially Raymond Klein for their useful comments. Bruce Milliken also helped improve our English. Pilar Gonzalvo helped us with data collecting. We are grateful to all of them.

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The emotions displayed by others can be cues to predict their behavior. Happy expressions are usually linked to positive consequences, whereas angry faces are associated with probable negative outcomes. However, there are situations in which the expectations we generate do not hold. Here, control mechanisms must be put in place. We designed an interpersonal game in which participants received good or bad economic offers from several partners. A cue indicated whether the emotion of their partner could be trusted or not. Trustworthy partners with happy facial expressions were cooperative, and angry partners did not cooperate. Untrustworthy partners cooperated when their expression was angry and did not cooperate when they displayed a happy emotion. Event-Related Potential (ERP) results showed that executive attention already influenced the frontal N1. The brain initially processed emotional expressions regardless of their contextual meaning but by the N300, associated to affective evaluation, emotion was modulated by control mechanisms. Our results suggest a cascade of processing that starts with the instantiation of executive attention, continues by a default processing of emotional features and is then followed by an interaction between executive attention and emotional factors before decision-making and motor stages.

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Steady-state visual evoked potential (SSVEP)-based brain-computer interfaces (BCIs) use the spectral power of the potentials for classification as they can be voluntarily enhanced or diminished by the subject by means of selective attention. The features traditionally extracted from the EEG and used for BCIs have been characterized as a normal distribution, although some studies have shown recently that this normal distribution is not the most appropriate for SSVEPs. In this paper we attempt to characterize the power of SSVEPs as a random variable that follows Rayleigh and exponential distributions when the stimulus is attended and ignored, respectively. BCIs based on SSVEPs can improve the transfer-bit and successful-classification rates if this new model is used instead of the traditional one based on the normal distribution.

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Two of the sources of information most relevant to guide social decisionmaking are the cooperative tendencies associated to different people and their facial emotional displays. The present electrophysiological experiment aimed to study how the use of personal identity and emotional expressions as cues impacts different stages of face processing and their potential isolated or interactive processing. Participants played a modified Trust Game with 8 different alleged partners, and in separate blocks either the identity or the emotions carried information regarding potential trial outcomes (win or loss).Behaviorally, participants were faster to make decisions based on identity compared to emotional expressions. Also, ignored (non-predictive) emotions interfered with decisions based on identity in trials where these sources of information conflicted. Electrophysiological results showed that expectations based on emotions modulated processing earlier in time than those based on identity. Whereas emotion modulated the central N1 and VPP potentials, identity judgments heightened the amplitude of the N2 and P3b. In addition, the conflict that ignored emotions generated was reflected on the N170 and P3b potentials. Overall, our results indicate that using identity or emotional cues to predict cooperation tendencies recruits dissociable neural circuits from an early point in time, and that both sources of information generate early and late interactive patterns.