The impact of item encoding mechanisms on associative memory in young and older adults
Final Report Abstract
We examined the hypothesis that during episodic memory encoding, older adults focus more strongly on readily presented item-specific details than mentally generating connections among different information units. This leads to a weaker encoding of associations, which may be a mechanism contributing to their disproportionate reduction in associative (compared to item) memory. We tested this hypothesis in four studies by experimentally manipulating the effort required to process and encode item information in pair encoding tasks and testing the effects on item and associative memory in young and older adults. In study 1, we manipulated the visual complexity of objects included in study pairs. While event-related potential (ERP) evidence showed neural patterns related to the processing of stimulus complexity (experiment 1, including only young adults), higher stimulus complexity did not enhance the magnitude of the age-related associative memory deficit (experiment 2). In study 2, half of the participants were familiarized with one stimulus of each pair 24 hours before completing an associative memory task. Prior familiarization enhanced item memory in both age groups, but did not affect the magnitude of the age-related associative memory deficit. EEG was recorded during the task, but ERP analyses were still ongoing at the time of completing the final project report. In study 3, we manipulated stimulus presentation times between subjects, thereby limiting the extent to which the presented visual item information could be focused on, while holding overall encoding times constant. Two experiments revealed that stimulus presentation times did not affect the magnitude of the associative memory deficit in older adults. In study 4, we manipulated item processing difficulty by presenting word-color pairs either in the native or in a foreign language (German) of young and older Italian native speakers. In an intentional encoding condition, the associative memory deficit of older adults was enhanced in the foreign language, thus supporting the main project hypothesis. However, an elaborate exploratory analysis suggested that individuals with a higher foreign language proficiency generally seem to encode items in a foreign language better than those with lower language proficiency, at the expense of lower associative memory, but that this effect was actually age-invariant. In study 4, we also found that older adults benefitted less from specific strategy instructions and that the benefit was lower in the foreign language. Together, we found no (study 1-3) or very limited (study 4) evidence for the project hypothesis of an item encoding focus at the expense of associative memory contributing to the relative age-related associative memory deficit. Since all studies used familiar, meaningful stimuli, it is unknown whether these results generalize to tasks in which a compensation of perceptual deficits by older adults’ intact semantic processes is not possible.
Publications
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Examining the role of stimulus complexity in item and associative memory. Memory & Cognition.
Endemann, Ricarda & Kamp, Siri-Maria
