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Carson Pun, Maha Adamo, Peter J. Lenkic, Susanne Ferber; Unfiltered and unforgotten: The fate of irrelevant visual stimuli in elderly adults. Journal of Vision 2009;9(8):574. doi: 10.1167/9.8.574.
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© ARVO (1962-2015); The Authors (2016-present)
The ability to hold visual information in mind after it is no longer physically present seems to decline with age. Our study investigates whether this age-related decline may be a derivative of the poor ability to filter out irrelevant information. It has been shown that the contents of visual short-term memory (VSTM) can be reflected electrophysiologically when the task involves ignoring irrelevant information. Specifically, we were interested in the contralateral delay activity (CDA) where a difference wave is computed by subtracting the ipsilateral from the contralateral activity when subjects view bilateral displays. The amplitude of this difference has been found to correlate with VSTM capacity. Furthermore, young adults with low capacity show a sustained increase in CDA when presented with irrelevant information, suggesting that they do not effectively ignore these distractors. Using EEG, we employed a VSTM paradigm where participants' attention was directed either to the left or to the right of a fixation cross and they were asked to perform a memory task consisting of colored squares with set sizes of one and three. In some trials, colored circles would be presented amongst the target squares and young and old participants were asked to ignore these distractors. Interestingly, the CDA response in elderly adults does not seem to discriminate between relevant and irrelevant items. This failure to prioritize relevant information may contribute to the typically observed age-related decline in working memory performance.
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