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Cathy Clarke, Michael Paradiso; A performance deficit at the site of attentional cueing. Journal of Vision 2003;3(9):327. doi: https://doi.org/10.1167/3.9.327.
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The spatial structure of attention was studied using a 2AFC task in which human and monkey subjects reported the color of a peripheral flashed bar stimulus. Stimuli were presented at the location of a static peripheral cue on a majority of trials and at uncued iso-eccentric probe locations on the remaining trials. In different experiments, the probability of a target at the cued location ranged from 60–80%. Surprisingly, we found that sensitivity (d') was highest for locations approximately 1 degree from the cued target location, and significantly lower for stimuli that appeared at or within 0.5 degrees of the cued location. Sensitivity decreased for stimuli appearing further than 1 degree from the cue. This pattern of sensitivity was obtained using different cue types and stimulus shapes. Because a target at the cued location was more probable than at the probe locations, we considered the possibility that the unusual performance deficit at the cued location was due to adaptation. However, this seems unlikely as we used 6 different bar orientations at the cued location so that no individual target at that location was more probable (and thus more able to adapt receptors) than a target at a probe location. Also, the effect was similar in experiments with a relatively long inter-trial interval (2.5 sec). The deficit at the cued location did not appear to be due to inhibition of return (IOR), because we observed the same spatial pattern of sensitivity when the cue was flashed with a cue-stimulus onset asynchrony of 100ms, a condition previously shown to not produce IOR. Our results suggest that visual performance is sometimes best a small distance away from the locus of attentional cueing rather than precisely at the cued location. At first glance our data appear to contradict the majority of work demonstrating peak performance at a cued target location. However, most previous cue-validity experiments did not probe performance at a scale as fine as in our study.
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