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Hayward J. Godwin, Tamaryn Menneer, Nick Donnelly; Weakened Target Representations in Low Prevalence Visual Search. Journal of Vision 2013;13(9):528. doi: https://doi.org/10.1167/13.9.528.
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© ARVO (1962-2015); The Authors (2016-present)
We examined the strength of activation of different target templates during a dual-target visual search task. We manipulated the proportion of trials where each target was presented (known as the target prevalence) in order to assess whether target templates are shaped by regularities in the environment. We recorded participants’ eye movement behaviour as they searched for two targets, one of which appeared on 45% of trials (TH) while the other appeared on 5% of trials (TL). We sought to determine whether guidance or identification processes (or both) were weakened by a reduction in target prevalence. Response accuracy data demonstrated that participants were less likely to detect TL than TH, replicating the prevalence effect. Analyses of eye movement behaviour indicated that guidance was weakened in low prevalence: participants were both less likely, and less rapid, to fixate distractors that shared their colour with TL than TH. Furthermore, identification processes in low prevalence search were also shown to be weakened, with the time between first fixating TL and responding ‘present’ being longer than the time between first fixating TH and responding ‘present’. Taken together, these results demonstrate that low target prevalence weakens target templates, both for guidance and recognition. This finding accounts for previous results, in which participants to fail to detect low prevalence targets, by showing that participants are less likely to fixate target objects, and, when they do, more time is required in order to identify those objects.
Meeting abstract presented at VSS 2013
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