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Hayward J. Godwin, Tamaryn Menneer, Shaun Helman, Kyle R. Cave, Nick Donnelly; In difficult visual search, high frequency targets are found at the expense of low frequency targets. Journal of Vision 2007;7(9):706. doi: https://doi.org/10.1167/7.9.706.
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© ARVO (1962-2015); The Authors (2016-present)
Previous studies have demonstrated that searching simultaneously for two dissimilar targets is very inefficient compared to searching separately for each target. This study investigated how this multiple-target cost interacts with the relative frequency of the appearance of two target classes. Response accuracy was measured during simultaneous search for either of two classes of targets, and compared against performance in independent single-target searches. Targets and distractors were complex objects, and a target was present on 50% of trials. The frequency with which the two classes of targets appeared in simultaneous multiple-target search was varied in two ways. One group of participants searched for multiple target classes that appeared with an equal frequency to one another. For the second group, one target class appeared nine times more regularly than the other. Accuracy in multiple-target search was compared with the accuracy for each target in single-target search. Accuracy was lower in multiple-target search for both targets when they appeared at an equal rate to one another, demonstrating a multiple-target cost over single-target search. However, there was no reduction in accuracy in the multiple-target search for the higher-frequency target, but there was a large reduction in accuracy for the lower-frequency target. When one target class is more frequent, effort is devoted to finding it, at the expense of finding the less frequent target class.
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