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Task preparation involves multiple component processes, including a general evaluative process that signals the need for adjustments in control, and the engagement of task-specific control settings. Here we examined the dynamics of these different mechanisms in preparing the attentional control system for visual search. We explored preparatory activity using pupil dilation, a well-established measure of task demands and effortful processing. In an initial exploratory experiment, participants were cued at the start of each trial to search for either a salient color singleton target (an easy search task) or a low-salience shape singleton target (a difficult search task). Pupil dilation was measured during the preparation period from cue onset to search display onset. Mean dilation was larger in preparation for the difficult shape target than the easy color target. In two additional experiments, we sought to vary effects of evaluative processing and task-specific preparation separately. Experiment 2 showed that when the color and shape search tasks were matched for difficulty, the shape target no longer evoked larger dilations, and the pattern of results was in fact reversed. In Experiment 3, we manipulated difficulty within a single feature dimension, and found that the difficult search task evoked larger dilations. These results suggest that pupil dilation reflects expectations of difficulty in preparation for a search task, consistent with the activity of an evaluative mechanism. We did not find consistent evidence for relationship between pupil dilation and search performance (accuracy and response timing), suggesting that pupil dilation during search preparation may not be strongly linked to ongoing task-specific preparation.
This article was published in the following journal.
Name: PloS one
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We investigated pupil dilation in 96 subjects during task preparation and during a post-trial interval in a visual search task and an auditory working memory task. Completely informative difficulty cu...
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The use of biological mechanisms, usually involving living organisms such as bacteria, for the reduction or regulation of the population of noxious, destructive, or dangerous pests. Environmental concerns have focused attention on natural forms of disease control as potentially safe and effective alternatives to chemical pesticides. This has led to increased efforts to develop control strategies that rely on natural predators and parasites or that involve genetically engineered microbial pest control agents.
The tendency to react to stimuli that are different from, but somewhat similar to, the stimulus used as a conditioned stimulus.
Agents causing contraction of the pupil of the eye. Because the size of the pupil is under the antagonistic control of the sympathetic and parasympathetic systems, drugs affecting either system can cause miosis. Drugs that mimic or potentiate the parasympathetic input to the circular constrictor muscle and drugs that inhibit sympathetic input to the radial dilator muscle tend to contract the pupils. Some sources use the term miotics only for the parasympathomimetics but any drug used to induce miosis is included here.
Unequal pupil size, which may represent a benign physiologic variant or a manifestation of disease. Pathologic anisocoria reflects an abnormality in the musculature of the iris (IRIS DISEASES) or in the parasympathetic or sympathetic pathways that innervate the pupil. Physiologic anisocoria refers to an asymmetry of pupil diameter, usually less than 2mm, that is not associated with disease.
Constriction of the pupil in response to light stimulation of the retina. It refers also to any reflex involving the iris, with resultant alteration of the diameter of the pupil. (Cline et al., Dictionary of Visual Science, 4th ed)