Process explanations of age-related changes in memory specificity.

Adult aging is associated with a decline in memory for the specific details of past experiences, but the reasons for these declines remain to be fully elucidated. Here, we consider the potential of computational process models of memory to reveal mechanisms underlying age-related changes in memory specificity. We define empirical benchmarks in the most widely used tasks for studying age differences in memory -- recognition and free recall. We then systematically review two broad classes of process models -- global matching and retrieved context models -- that are well-suited to explaining these benchmarks. We discuss and at times illustrate through simulations how age differences in memory specificity can arise from different mechanisms in these models, such as reductions in encoding fidelity, cue-selectivity of retrieval, contextual reinstatement, or retrieval monitoring. These models hold great promise for uncovering the latent mechanisms of age-related memory change, but several explanatory shortcomings must be addressed for a more comprehensive theory to emerge. Because process models often incorporate simplifying shortcuts, they risk advancing descriptive rather than mechanistic explanations for age differences in memory. Furthermore, models that have identified multiple processes of age-related memory impairment have left unaddressed the ways in which these processes affect each other. By illuminating these and other challenges in current process models, our review aims to stimulate future advances that can dramatically reshape our understanding of the processes of age-related changes in memory specificity.

This study examined the effects of dual task requirements on age differences in free recall performance. One thousand adults ranging in age between 35 and 80 years performed a word recall task alone and concurrently with a card-sorting task (at encoding, retrieval, or both). Age differences in memory performance were substantial under single task conditions, but after correcting memory performance under dual task conditions for differences in single task performance, age did not predict performance. These results do not support the hypothesis that reduced attentional capacity in old age is underlying age differences in episodic memory.

An experiment is reported in which young and elderly subjects listened to and recalled spoken passages that ranged from highly predictable to low in predictability, under both single-task conditions and dual-task conditions in which passages were presented concurrently with a speeded matching task. Age differences in memory for the passages were shown to vary according to both the predictability of the text, and the level of importance of information. Although the elderly recalled less than the young, they showed similar patterns of recall for major ideas. At the level of details, however, age differences were larger as passages became less predictable. Age differences in memory were not magnified by the requirement to divide attention, regardless of whether an easy or more difficult concurrent task was presented. These findings suggest that although speech-processing ability in old age shows considerable resilience to conditions of heavy load, including divided attention, age-related changes may be observed at lower levels of information.

Older adults often report memories of past events that are partly false. To date, age differences in memory errors have primarily been examined after a delay of minutes to hours. However, in real-life situations we rely on memories formed days to weeks in the past. We examined associative memory for unrelated scene-word pairs in younger and older adults after 24 hr and 8 days. Age differences in memory were magnified after 8 days due to a disproportionate increase in false alarms to rearranged pairs in older adults. In both age groups, the effects of delay were modulated by memory fidelity and whether or not participants had experienced similar events, which potentially caused interference. Older adults were particularly vulnerable to associative memory errors having experienced similar events, even when the initial memory was of high fidelity. We suggest that the fidelity of memory representations in concert with monitoring processes to resolve interference determine how the passage of time affects the propensity to falsely remember details of the past. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

The slow oscillation (SO) observed during deep sleep is known to facilitate memory consolidation. However, the impact of age-related changes in sleep electroencephalography (EEG) oscillations and memory remains unknown. In this study, we aimed to investigate the contribution of age-related changes in sleep SO and its role in memory decline by combining EEG recordings and computational modeling. Based on the detected SO events, we found that older adults exhibit lower SO density, lower SO frequency, and longer Up and Down state durations during N3 sleep compared to young and middle-aged groups. Using a biophysically detailed thalamocortical network model, we simulated the "aged" brain as a partial loss of synaptic connections between neurons in the cortex. Our simulations showed that the changes in sleep SO properties in the "aged" brain, similar to those observed in older adults, resulting in impaired memory consolidation. Overall, this study provides mechanistic insights into how age-related changes modulate sleep SOs and memory decline.Clinical Relevance- This study contributes towards finding feasible biomarkers and target mechanism for designing therapy in older adults with memory deficits, such as Alzheimer's disease patients.

Age differences in adults' memory for performed actions (e.g., wave hand) are sometimes smaller than age differences in memory for nonperformed phrases. In this study, we examined the conditions under which performance reduces age differences in recall. Younger and older adults performed or read verb-noun phrases that were either related (e.g., actions performed in a kitchen) or unrelated. Performance did not reduce age differences in recall of the exact verbs and nouns used to describe an action, but performance did reduce age differences in memory for the gist of related actions. Older adults especially had difficulty recalling the exact verb used to describe the action. These results suggest that older adults may have better memory for actions than is revealed by tests of verbatim recall. They may remember performing the action but not remember the exact words used to describe the action.

Contributions of self-reported health to adult age differences in perceptual speed and memory were assessed for 301 adults ages 20-90. Participants were asked 4 health status questions, given 3 perceptual speed tests, 2 working memory tests, and 2 memory tests. Self-reported health was found to predict speed better than it predicted memory. Covariance structural equation modeling was used to assess the relations among age, self-reported health, perceptual speed, working memory, and memory. The results support the hypothesis that any effects of self-reported health on age differences in memory are mediated by perceptual speed.

Recent research suggests that affective and motivational processes can influence age differences in memory. In the current study, we examine the impact of both natural and induced mood state on age differences in false recall. Older and younger adults performed a version of the Deese–Roediger–McDermott (DRM; Roediger & McDermott, 1995, Journal of Experimental Psychology: Learning, Memory, and Cognition, 21, 803) false memory paradigm in either their natural mood state or after a positive or negative mood induction. Results indicated that, after accounting for age differences in basic cognitive function, age-related differences in positive mood during the testing session were related to increased false recall in older adults. Inducing older adults into a positive mood also exacerbated age differences in false memory. In contrast, veridical recall did not appear to be systematically influenced by mood. Together, these results suggest that positive mood states can impact older adults' information processing and potentially increase underlying cognitive age differences.

Very little is known about whether and how socioemotional factors influence age differences in associative memory. Here, we tested the hypothesis that reducing the threat induced by age-based stereotypes can reduce age differences in learning performance and strategy. Using an associative learning task, we replicated the classic finding of age differences under a high-threat condition: older adults had longer reaction times than younger adults and were much more reluctant to use memory retrieval. However, age differences were greatly diminished under a low-threat condition. These findings demonstrate that memory retrieval is an ability not entirely lost as individuals age because merely reducing stereotype threat helped restoring it. We conclude that socioemotional factors, such as stereotype threat, should be considered when evaluating younger and older adults' memory performance.

Despite the number of documented declines in memory with age, memory for socioemotional information can be preserved into older adulthood. These studies assessed whether memory for character information could be preserved with age, and how the general versus specific nature of the information tested affected outcomes. We hypothesized that memory for general impressions would be preserved with age, but that memory for specific details would be impaired. In two experiments, younger and older adults learned character information about individuals characterized as positive, neutral, or negative. Participants then retrieved general impressions and specific information for each individual. The testing conditions in Experiment 2 discouraged deliberate recall. In Experiment 1, we found that younger performed better than older adults on both general and specific memory measures. Although age differences in memory for specific information persisted in Experiment 2, we found that younger and older adults remembered general impressions to a similar extent when testing conditions encouraged the use of “gut impressions” rather than deliberate retrieval from memory. We conclude that aging affects memory for specific character information, but memory for general impressions can be age-equivalent. Furthermore, there is no evidence for a positivity bias or differences in the effects of valence on memory across the age groups.

While age-related changes in memory have been well documented, findings about jurors’ perceptions of older witnesses are conflicting. We investigated the effect of victim age (25 vs. 75 years old) and crime severity (victim injured vs. not injured) on mock jurors’ decisions in a robbery trial. Jury-eligible participants (120 women; 84 men) read a mock trial summary and delivered their verdicts online. Mock jurors believed the young victim more than the older victim when the crime was severe, while no age differences emerged for the less severe crime. Whereas previous research demonstrated that juror characteristics were generally associated with culpability, we demonstrated that with case-specific information, these general views became less important. In all, mock jurors were aware of age-related decline in memory provided by eyewitnesses only to a limited extent. Accordingly, in trials involving older witnesses, jurors will benefit from educative information about age-related memory changes.

Our understanding of the ways in which changes in specific neural systems mediate adult age differences in memory is rapidly increasing, due in no small part to the advent of functional neuroimaging techniques. This article reviews age-related changes in memory performance obtained with behavioral measures, describes models of the neural mechanisms of memory, and derives predictions from these models regarding age-related changes in brain activation patterns. The neuroimaging findings obtained to date support models emphasizing the role of prefrontal cortex in age-related changes in memory functioning, especially for episodic memory retrieval. In general, neural activation associated with episodic memory encoding is regionally similar for younger and older adults but relatively lower in magnitude for older adults. During retrieval, activation that is restricted to the right prefrontal cortex for younger adults is more likely to be bilateral for older adults. Prefrontal activation exhibits an age-related increase when working memory tasks require simple storage and an age-related decrease when working memory requires higher-level executive processes. Although the evidence is limited, behavioral performance and activation patterns appear to be similar among younger and older adults on tests of semantic (context-independent) and implicit memory. We conclude that several methodological issues, such as defining the relation between brain structure and function, and determining the relationship between performance and activation, are particularly important for understanding age-related changes. Future directions for aging research include further investigation of the relation between encoding and retrieval and the identification of both spared and impaired neural systems.

In this article, we apply the REM model (Shiffrin & Steyvers, 1997) to age differences in associative memory. Using Criss and Shiffrin's (2005) associative version of REM, we show that in a task with pairs repeated across 2 study lists, older adults' reduced benefit of pair repetition can be produced by a general reduction in the diagnosticity of information stored in memory. This reduction can be modeled similarly well by reducing the overall distinctiveness of memory features, or by reducing the accuracy of memory encoding. We report a new experiment in which pairs are repeated across 3 study lists and extend the model accordingly. Finally, we extend the model to previously reported data using the same task paradigm, in which the use of a high-association strategy introduced proactive interference effects in young adults but not older adults. Reducing the diagnosticity of information in memory also reduces the proactive interference effect. Taken together, the modeling and empirical results reported here are consistent with the claim that some age differences that appear to be specific to associative information can be produced via general degradation of information stored in memory. The REM model provides a useful framework for examining age differences in memory as well as harmonizing seemingly conflicting prior modeling approaches for the associative deficit. (PsycINFO Database Record

Learning and memory in the SAMP8 mouse

There is considerable experimental literature showing that memory for complex pictures is relatively insensitive to age. Previous research has shown that young and old adults do not differ in their ability to recognize complex scenes. Other studies, however, using simple line drawings, do find age differences. This experiment investigated the possibility that the failure to find age differences with memory for complex pictures occurs because of memory support provided at encoding and retrieval by both the degree of visual detail (complex perceptual information) and the degree of propositional content (linguistic meaningfulness) that are represented in complex scenes. Pictures were shown to young and old subjects that differed in visual detail (complex vs simple) and propositional content (concrete vs abstract). The results indicated that age differences in picture memory emerge if the pictures are either deprived of visual detail or reduced in propositional content.