Attention was focused at a specific location either by a briefly flashed cue (cue-induced attention) or by a voluntary effort (voluntary attention). In both cases, briefly presented probes appeared displaced away from the focus of attention. The results showed that the effect of cue-induced attention was transient whereas the effect of voluntary attention was long lasting. The repulsion effect was most evident with brief probe durations (<200 ms). Control experiments ruled out nonattentional hypotheses based on classic figural aftereffects and apparent motion. Although a number of studies have demonstrated enhancements of visual perception at attended locations, the present studies show that focused attention can distort the encoding of nearby positions. Speculation is offered that the repulsion effect is one of the costs involved in the allocation of more resources to the focus of attention. Attention is often regarded as a mechanism by which our brains selectively gate a subset of sensory stimulation into consciousness. In the visual modality, we normally attend to sensory signals coming through the central region of the retina in and around the fovea. In casual terms, we normally "see" what we are looking at. Because of the high cone density and cortical magnification factor, the fovea affords the highest sensitivity and acuity under photopic conditions. It thus makes sense that our visual systems normally gate the highest quality signals coming through the small region centered around the fovea into conscious processing. Stimuli of interest are brought into the fovea by way of saccadic and smooth-pursuit eye movements. However, most of us can voluntarily direct attention away from the fovea and focus it at some location in the periphery. Common introspection is that voluntarily focused attention in the periphery somehow helps us see and react faster to events in the attended region. In fact, as early as in the late 19th century, Helmholtz (1896) reported enhanced contrast sensitivity at voluntarily attended locations. The focus of attention can also be attracted to abrupt spatial-temporal discontinuities. A sudden flash of intense

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The ability to track multiple moving objects with attention has been the focus of much research. However, the literature is relatively inconclusive regarding two key aspects of this ability, (1) whether the distribution of attention among the tracked targets is fixed during a period of tracking or is dynamically adjusted, and (2) whether motion information (direction and/or speed) is used to anticipate target locations even when velocities constantly change due to inter-object collisions. These questions were addressed by analyzing target-localization errors. Targets in crowded situations (i.e., those in danger of being lost) were localized more precisely than were uncrowded targets. Furthermore, the response vector (pointing from the target location to the reported location) was tuned to the direction of target motion, and observers with stronger direction tuning localized targets more precisely. Overall, our results provide evidence that multiple-object tracking mechanisms dynamically adjust the spatial distribution of attention in a demand-based manner (allocating more resources to targets in crowded situations) and utilize motion information (especially direction information) to anticipate target locations.

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The current study investigated the influence of a low-level local feature (curvature) and a high-level emergent feature (facial expression) on rapid search. These features distinguished the target from the distractors and were presented either alone or together. Stimuli were triplets of up and down arcs organized to form meaningless patterns or schematic faces. In the feature search, the target had the only down arc in the display. In the conjunction search, the target was a unique combination of up and down arcs. When triplets depicted faces, the target was also the only smiling face among frowning faces. The face-level feature facilitated the conjunction search but, surprisingly, slowed the feature search. These results demonstrated that an object inferiority effect could occur even when the emergent feature was useful in the search. Rapid search processes appear to operate only on high-level representations even when low-level features would be more efficient.