On the role of item encoding mechanisms in associative memory in young and older adults: A mass univariate ERP study

Abstract

We examined the role of item encoding mechanisms in older adults' disproportionate deficit in memory for associations and individual differences therein. Young and older adults encoded sequentially presented object pairs via interactive imagery while their EEG was recorded. Compared to the young adults, older adults exhibited a reduction in associative, but not in item memory performance. Young adults showed frontal slow wave subsequent memory effects (SME) in both an item encoding contrast and an associative encoding contrast, presumably reflecting elaborative item processing, as well as the elaboration of an internal interactive image. Based on their performance in the subsequent associative memory test, older adults were subdivided into a high and a low performing group. In low performers, instead of a frontal slow wave SME a polarity-reversed, early parietal item SME was prominent, whose magnitude was negatively correlated with associative memory performance, potentially reflecting shallow, perceptual item encoding processes that are not well-suited for the formation of new associations. The present findings suggest that age-related deficits in elaboration of item information and an emphasis on the encoding of perceptual, item-specific details may contribute to reduced associative memory performance in older adults.

Keywords: Aging; Associative elaboration; Frontal slow wave; Individual differences; Item elaboration; Subsequent memory effect.