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This paper reports a series of experiments that were carried out in order to study the attentional system. Three networks make up this system, and each of them specializes in particular processes. The executive control network specializes in control processes, such as conflict resolution or detection of errors; the orienting network directs the processing system to the source of input and enhances its processing; the alerting network prepares the system for a fast response by maintaining an adequate level of activation in the cognitive system. Recently, Fan and collaborators [J Cogn Neurosci 14(3):340-347, 2002] designed a task to measure the efficiency of each network. We modified Fan's task to test the influences among the networks. We found that the executive control network is inhibited by the alerting network, whereas the orienting network raises the efficiency of the executive control network (Experiment 1). We also found that the alerting network influences the orienting network by speeding up its time course function (Experiment 2). Results were replicated in a third experiment, proving the effects to be stable over time, participants and experimental context, and to be potentially important as a tool for neuropsychological assessment.

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.

No abstract

Endogenous temporal-orienting effects were studied using a cuing paradigm in which the cue indicated the time interval during which the target was most likely to appear. Temporal-orienting effects were defined by lower reaction times (RTs) when there was a match between the temporal expectancy for a target (early or late) and the time interval during which the target actually appeared than when they mismatched. Temporal-orienting effects were found for both early and late expectancies with a detection task in Experiment 1. However, catch trials were decisive in whether temporal-orienting effects were observed in the early-expectancycondition. No temporal-orienting effects were found in the discrimination task. In Experiments 2A and 2B, temporal-orienting effects were observed in the discrimination task; however, they were larger when temporal expectancy was manipulated between blocks, rather than within blocks.