A simulation of older adults’ associative memory deficit using structural process interference in young adults

Associative memory deficit underlies a part of older adults’ deficient episodic memory due to the reduced ability to bind units of information. In this article we further assess the mechanism underlying this deficit, by assessing the degree to which we can model it in young adults under conditions of divided attention. We shall describe two experiments in this paper; these experiments investigate item and associative recognition in young adults under full- or divided-attention conditions. The secondary tasks employed were N-back like (NBL), which serves as a working memory updating task, and parity judgement and visuospatial (VS) tasks, which serve as non-working memory tasks. The results of both experiments show that only the NBL specifically affected associative recognition, while the other tasks affected item and associative memory to the same degree, indicating a general resource competition. These results presented a convergence of evidence for the associative deficit in older adults by modelling it in young adults.

Age-related associative memory deficit: simulation and strategies to improve performance

According to the associative deficit hypothesis, older adults experience greater difficulty in remembering associations between pieces of information (associative memory) than young adults, despite their relatively intact memory for individual items (item memory). Recent research suggests that this deficit might be related to older adults’ reduced availability of attentional resources – the reservoir of mental energy needed for the operations of cognition functions. The purpose of this Dissertation was to examine the role of attentional resources in associative deficit, and to explore encoding manipulations that might alleviate the deficit in older adults. In Study 1, young adults’ attentional resources during encoding of word pairs were depleted using a divided attention task. These participants showed an associative deficit commonly observed in older adults, and were less likely to use effective encoding strategies and recollection-based processes to support their memory in comparison to young adults under full attention. The resemblance in memory performance between young adults under divided attention and older adults suggests that lack of attentional resources might be a contributing factor in older adults’ associative deficit. In Study 2, participants’ resource load during encoding was reduced by learning individual items and their associations sequentially in two phases. Older adults in this condition showed equivalent memory performance to young adults, and were more likely to use effective encoding strategies and recollection-based processes than older adults in Study 1 who studied items and associations simultaneously. Finally, Study 3 employed a value-directed learning paradigm, in which participants studied high- and low-value word pairs. Older adults showed similar memory performance for both high- and low-value word pairs as young adults, without any signs of associative deficit. Assigning value to associative information might prompt older adults to prioritize associative encoding over item encoding, which benefits their associative memory. Taken together, these results suggest that depletion of attentional resources during encoding could impair associative memory. Furthermore, older adults’ associative deficit could be effectively alleviated with sufficient environmental support during encoding, such as when resource competition between item and associative encoding is minimized (Study 2) or when being guided to prioritize encoding of associations over items (Study 3).

Age-related associative memory deficit: simulation and strategies to improve performance

According to the associative deficit hypothesis, older adults experience greater difficulty in remembering associations between pieces of information (associative memory) than young adults, despite their relatively intact memory for individual items (item memory). Recent research suggests that this deficit might be related to older adults’ reduced availability of attentional resources – the reservoir of mental energy needed for the operations of cognition functions. The purpose of this Dissertation was to examine the role of attentional resources in associative deficit, and to explore encoding manipulations that might alleviate the deficit in older adults. In Study 1, young adults’ attentional resources during encoding of word pairs were depleted using a divided attention task. These participants showed an associative deficit commonly observed in older adults, and were less likely to use effective encoding strategies and recollection-based processes to support their memory in comparison to young adults under full attention. The resemblance in memory performance between young adults under divided attention and older adults suggests that lack of attentional resources might be a contributing factor in older adults’ associative deficit. In Study 2, participants’ resource load during encoding was reduced by learning individual items and their associations sequentially in two phases. Older adults in this condition showed equivalent memory performance to young adults, and were more likely to use effective encoding strategies and recollection-based processes than older adults in Study 1 who studied items and associations simultaneously. Finally, Study 3 employed a value-directed learning paradigm, in which participants studied high- and low-value word pairs. Older adults showed similar memory performance for both high- and low-value word pairs as young adults, without any signs of associative deficit. Assigning value to associative information might prompt older adults to prioritize associative encoding over item encoding, which benefits their associative memory. Taken together, these results suggest that depletion of attentional resources during encoding could impair associative memory. Furthermore, older adults’ associative deficit could be effectively alleviated with sufficient environmental support during encoding, such as when resource competition between item and associative encoding is minimized (Study 2) or when being guided to prioritize encoding of associations over items (Study 3).

Relational binding and holistic retrieval in aging

Episodic memory binds together diverse elements of an event into a cohesive unit. This property enables the reconstruction of multidimensional experiences when triggered by a cue related to a past event via pattern completion processes. Such holistic retrieval is evident in young adults, as shown by dependency in the retrieval success for different associations from the same event (Horner & Burgess, 2013, 2014). Aspects of episodic memory capacity are vulnerable to aging processes, as shown by reduced abilities to form linkages within an event through relational binding (associative deficit hypothesis: Naveh-Benjamin, 2002). However, prior work has not examined whether this reduction affects holistic retrieval in typical aging. Here, we leveraged dependency analyses to examine whether older adults remember or forget events holistically, and whether the degree of holistic retrieval declines with old age. We found evidence for continued holistic retrieval, because accuracy for one aspect of an event predicted accuracy for other aspects of the same event. Younger and older adults did not differ in the degree of holistic recollection, despite robust age-related differences in relational binding. However, within the group of older adults, holistic recollection showed a significant decline with advancing age, controlling for pairwise relational binding performance, verbal IQ, and general cognitive status. These results suggest that a decline in holistic retrieval is an aspect of episodic memory decrements later in cognitive aging.

Does limited working-memory capacity underlie age differences in associative long-term memory?

Past research has consistently shown that episodic memory (EM) declines with adult age and, according to the associative-deficit hypothesis, the locus of this decline is binding difficulties. We investigated the importance of establishing and maintaining bindings in working memory (WM) for age differences in associative EM. In Experiment 1 we adapted the presentation rate of word pairs for each participant to achieve 67% correct responses during a WM test of bindings in young and older adults. EM for the pairs was tested thereafter in the same way as WM. Equating WM for bindings between young and older adults reduced, but did not fully eliminate, the associative EM deficit in the older adults. In Experiment 2 we varied the set size of word pairs in a WM test, retaining the mean presentation rates for each age group from Experiment 1. If a WM deficit at encoding causes the EM deficit in older adults, both WM and EM performance should decrease with increasing set size. Against this prediction, increasing set size did not affect EM. We conclude that reduced WM capacity does not cause the EM deficit of older adults. Rather, both WM and EM deficits are reflections of a common cause, which can be compensated for by longer encoding time.

Age-related Decline in Associative Memory: Understanding the Roles of Controlled and Automatic Processes

Memory decline in old age is highly noticeable based on tasks assessing episodic memory, which require remembering information about events at specific times and places. The exact cognitive mechanism that accounts for this prominent age-related decline in episodic memory has not been well-understood, and the multitude of mechanisms that were proposed have drawn a credible amount of research and discussions. The current review focuses on the associative deficit hypothesis (ADH) - originally proposed by Naveh-Benjamin and colleagues - that was suggested to form the basis of age-related declines in episodic memories. According to the ADH, older adults’ poorer episodic memory is attributed to the difficulties they experience in formulating relations or links between single units of information (i.e., items or contextual elements), binding them together into a coherent distinctive unit, and retrieving the links between the component features/units whenever necessary [COPYRIGHT CC-BY-NC-ND 4.0 J. Y. ZHONG, 2018].