Effects of emotional arousal on memory binding in normal aging and Alzheimer's disease

Previous research suggests that associative memory declines in normal aging and is severely affected by Alzheimer's disease (AD); however, it is unclear whether and how this deficit can be minimized. The present study investigated whether emotional arousal improves associative memory in healthy younger and older adults and patients with probable AD. We examined the effect of arousal on memory for item-location associations. Arousal improved memory for item location similarly across the three groups, whereas valence had no effect in any groups. Overall, our results suggest that arousal has beneficial effects on associative memory in healthy older adults and patients with AD, as previously observed in younger adults.     

The effects of presentation rate and retention interval on memory for items and associations in younger adults: A simulation of older adults’ associative memory deficit

Older adults show an associative deficit in episodic memory compared to younger adults. Previous research suggests both strategic and automatic binding deficits contribute to older adults’ poorer memory performance. Using behavioral manipulations designed to affect strategic and automatic binding of associations, three experiments attempted to simulate an associative deficit in younger adults. In these experiments participants learned face-scene pairs and then were given item and associative recognition memory tests. We manipulated the time allotted at encoding and retrieval to simulate strategic deficits, and the length of the retention interval to simulate automatic deficits. Results indicate that both manipulations separately contribute to a differential decline in associative memory, similar to the one shown by older adults, especially as reflected in the differential increase in false alarm rate in the associative memory test more than in the item memory test. Considerations of possible underlying brain mechanisms are discussed.     

The effects of aging and divided attention on memory for item and associative information

The present study examined how aging and divided attention influence memory for item and associative information. Older adults and younger adults working under full-attention conditions and younger adults working under divided-attention conditions studied unrelated word pairs. Memory for item information was measured by later recognition of the 2nd word in the pair, and associative information was measured by recognition of the entire pair. Both older adults in the full-attention condition and younger adults in the divided-attention condition performed more poorly than younger adults in the full-attention condition, with the deficit in associative information being greater than the deficit in item information. In addition, a differentially greater associative decrement was found for the older adults, as shown by their heightened tendency to make false-alarm responses to re-paired (conjunction) distractors. The results are discussed in terms of an age-related reduction in processing resources compounded by an age-related increase in older adults' reliance on familiarity in associative recognition memory.     

Differential effects of alcohol on associative versus item memory

Alcohol has detrimental effects on a range of cognitive processes, the most prominent being episodic memory. These deficits appear functionally similar to those observed within the normal aging population. We investigated whether an associative memory deficit, as found in older adults, would also be evident in young adults moderately intoxicated by alcohol. Participants were shown unrelated word pairs and then tested on both their item recognition (old/new item?) and associative recognition (intact/recombined pair?). Half the participants were under the influence of alcohol whereas the other half were sober. Alcohol impaired memory performance but significantly more so for associative than for item memory. Moreover, within the alcohol group, the associative memory deficit was significantly related to the amount of alcohol consumed. The findings suggest that not all aspects of episodic memory are equally impaired by alcohol, which may have practical implications for criminal investigations involving eye witnesses who have consumed alcohol.     

Differential effects of age on item and associative measures of memory: a meta-analysis

In this meta-analysis, the authors evaluated recent suggestions that older adults' episodic memory impairments are partially due to a reduced ability to encode and retrieve associated/bound units of information. Results of 90 studies of episodic memory for both item and associative information in 3,197 young and 3,192 older adults provided support for the age-related associative/binding deficit suggestion, indicating a larger effect of age on memory for associative information than for item information. Moderators assessed included the type of associations, encoding instructions, materials, and test format. Results indicated an age-related associative deficit in memory for source, context, temporal order, spatial location, and item pairings, in both verbal and nonverbal material. An age-related associative deficit was quite pronounced under intentional learning instructions but was not clearly evident under incidental learning instructions. Finally, test format was also found to moderate the associative deficit, with older adults showing an associative/binding deficit when item memory was evaluated via recognition tests but not when item memory was evaluated via recall tests, in which case the age-related deficits were similar for item and associative information.     

Attention and the acquisition of new knowledge: their effects on older adults' associative memory deficit

Older adults experience a selective associative memory deficit by demonstrating intact item memory relative to impaired associative memory when compared with younger adults. Age-related deficits in associative memory have been suggested to arise from declines in attentional resources, and the role of attention during encoding and retrieval in associative memory for words and their spatial locations was investigated in the current experiment. Additionally, the tendency of younger and older adults to use knowledge acquired during encoding to improve their associative memory judgments through a strategic associative memory process was also investigated. Younger and older adults studied a list of words with each word belonging to one of four categories, which followed one of four mathematical probability structures for their presentation. Older adults exhibited intact item memory and impaired associative memory relative to full attention younger adults. In addition, both older and younger adults demonstrated an ability to engage in strategic associative memory, by learning and later using the probability structure introduced at study to guide their associative memory judgments. In contrast, dividing the attention of younger adults during encoding impaired item memory, associative memory and strategic associative memory, whereas dividing attention at retrieval did not result in similar deficits. These data add to a growing body of literature demonstrating older adults to exhibit a selective associative memory deficit that is not simulated by dividing the attention of younger adults at encoding or retrieval. Furthermore, younger and older adults maintain the ability to use new knowledge to guide their associative judgments.     

Older adults’ associative deficit in episodic memory: Assessing the role of decline in attentional resources

In this study, we evaluated an associative deficit hypothesis. This hypothesis suggests that the deficit seen in the episodic memory performance of older adults is due, in considerable part, to older adults’ difficulty in binding together unrelated components of an episode into a cohesive entity (Naveh-Benjamin, 2000). The study extended the conditions under which older adults show a differential deficit in tests requiring associations among the episode components to situations in which the item and the associative recognition tests are equated on the response mode used and on the amount of information displayed. In addition, we tested the potential role of a decrease in attentional resources in the associative deficit of older adults by comparing their performance to that of younger adults under conditions of reduced attentional resources. The results of the study, which indicate that younger adults under divided attention do not show an associative deficit, are interpreted as indicating that the associative deficit of older adults is due to factors other than depleted attentional resources.     

The effects of emotional arousal and gender on the associative memory deficit of older adults

In this study we assessed the potential moderating roles of stimulus type (emotionally arousing) and participants’ characteristics (gender) in older adults’ associative memory deficit. In two experiments, young and older participants studied lists that included neutral and emotionally arousing word pairs (positive and negative) and completed recognition tests for the words and their associations. In Experiment 1, the majority of the word pairs were composed of two nouns, whereas in Experiment 2 they were composed of adjective–noun pairs. The results extend evidence for older adults’ associative deficit and suggest that older and younger adults’ item memory is improved for emotionally arousing words. However, associative memory for the word pairs did not benefit (and even showed a slight decline) from emotionally arousing words, which was the case for both younger and older adults. In addition, in these experiments, gender appeared to moderate the associative deficit of older adults, with older males but not females demonstrating this deficit.     

Aging, source memory, and emotion

In 2 experiments we assessed younger and older adults' ability to remember contextual information about an event. Each experiment examined memory for 3 different types of contextual information: (a) perceptual information (e.g., location of an item); (b) conceptual, nonemotional information (e.g., quality of an item); and (c) conceptual, emotional information (e.g., safety of an item). Consistent with a large literature on aging and source memory, younger adults outperformed older adults when the contextual information was perceptual in nature and when it was conceptual, but not emotional. Age differences in source memory were eliminated, however, when participants recalled emotional source information. These findings suggest that emotional information differentially engages older adults, possibly evoking enhanced elaborations and associations. The data are also consistent with a growing literature, suggesting that emotional processing remains stable with age (e.g., Carstensen & Turk-Charles, 1994, 1998; Isaacowitz, Charles, & Carstensen, 2000).     

Assessing the associative deficit of older adults in long-term and short-term/working memory

Older adults exhibit a deficit in associative long-term memory relative to younger adults. However, the literature is inconclusive regarding whether this deficit is attenuated in short-term/working memory. To elucidate the issue, three experiments assessed younger and older adults' item and interitem associative memory and the effects of several variables that might potentially contribute to the inconsistent pattern of results in previous studies. In Experiment 1, participants were tested on item and associative recognition memory with both long-term and short-term retention intervals in a single, continuous recognition paradigm. There was an associative deficit for older adults in the short-term and long-term intervals. Using only short-term intervals, Experiment 2 utilized mixed and blocked test designs to examine the effect of test event salience. Blocking the test did not attenuate the age-related associative deficit seen in the mixed test blocks. Finally, an age-related associative deficit was found in Experiment 3, under both sequential and simultaneous presentation conditions. Even while accounting for some methodological issues, the associative deficit of older adults is evident in short-term/working memory. (PsycINFO Database Record (c) 2012 APA, all rights reserved).     

Age-related differences in the von restorff isolation effect

When one item is made distinct from the other items in a list, memory for the distinctive item is improved, a finding known as the isolation or von Restorff effect (after von Restorff, 1933). Although demonstrated numerous times with younger adults and children, this effect has not been found with older adults (Cimbalo & Brink, 1982). In contrast to the earlier study, we obtained a significant von Restorff effect for both younger and older adults using a physical manipulation of font colour. The effect size for older adults was smaller than that obtained for younger adults, confirming a prediction of Naveh-Benjamin's (2000) associative deficit hypothesis, which attributes age-related differences in memory performance to older adults' reduced ability to form associations. The findings are consistent with related research in which older adults demonstrate similar—but smaller—benefits for distinctive information to those for younger adults.     

Differential age-related effects on conjunctive and relational visual short-term memory binding

An age-related associative deficit has been described in visual short-term binding memory tasks. However, separate studies have suggested that ageing disrupts relational binding (to associate distinct items or item and context) more than conjunctive binding (to integrate features within an object). The current study directly compared relational and conjunctive binding with a short-term memory task for object–colour associations in 30 young and 30 older adults. Participants studied a number of object–colour associations corresponding to their individual object span level in a relational task in which objects were associated to colour patches and a conjunctive task where colour was integrated into the object. Memory for individual items and for associations was tested with a recognition memory test. Evidence for an age-related associative deficit was observed in the relational binding task, but not in the conjunctive binding task. This differential impact of ageing on relational and conjunctive short-term binding is discussed by reference to two underlying age-related cognitive difficulties: diminished hippocampally dependent binding and attentional resources.     

The effects of pure pair repetition on younger and older adults' associative memory

Although aging causes relatively minor impairment in recognition memory for components, older adults' ability to remember associations between components is typically significantly compromised, relative to that of younger adults. This pattern could be associated with older adults' relatively intact familiarity, which helps preserve component memory, coupled with a marked decline in recollection, which leads to a decline in associative memory. The purpose of the current study is to explore possible methods that allow older adults to rely on pair familiarity in order to improve their associative memory performance. Participants in 2 experiments were repeatedly presented with either single items or pairings of items prior to a study list so that the items and the pairs were already familiar during the study phase. Pure pair repetition (the effects of pair repetition after the effects of item repetition are taken into account) increased associative memory for older and younger adults. Findings based on remember and know judgments suggest that familiarity but not recollection is involved in mediating the repetition effect.     

Age-related differences in the von Restorff isolation effect

When one item is made distinct from the other items in a list, memory for the distinctive item is improved, a finding known as the isolation or von Restorff effect (after von Restorff, 1933). Although demonstrated numerous times with younger adults and children, this effect has not been found with older adults (Cimbalo & Brink, 1982). In contrast to the earlier study, we obtained a significant von Restorff effect for both younger and older adults using a physical manipulation of font colour. The effect size for older adults was smaller than that obtained for younger adults, confirming a prediction of Naveh-Benjamin's (2000) associative deficit hypothesis, which attributes age-related differences in memory performance to older adults' reduced ability to form associations. The findings are consistent with related research in which older adults demonstrate similar—but smaller—benefits for distinctive information to those for younger adults.     

Effects of aging and divided attention on memory for items and their contexts

It is commonly found that memory for context declines disproportionately with aging, arguably due to a general age-related deficit in associative memory processes. One possible mechanism for such deficits is an age-related reduction in available processing resources. In two experiments we compared the effects of aging to the effects of division of attention in younger adults on memory for items and context. Using a technique proposed by Craik (1989), linear functions relating memory performance for items and their contexts were derived for a Young Full Attention group, a Young Divided Attention group, and an Older Adult group. Results suggested that the Old group showed an additional deficit in associative memory that was not mimicked by divided attention. It is speculated that both divided attention and aging are associated with a loss of available processing resources that may reflect inefficient frontal lobe functioning, whereas the additional age-related decrement in associative memory may reflect inefficient processing in medial-temporal regions.     

The role of source memory in older adults' recollective experience

Younger adults' "remember" judgments are accompanied by better memory for the source of an item than "know" judgments. Furthermore, remember judgments are not merely associated with better memory for individual source features but also with bound memory for multiple source features. However, older adults, independent of their subjective memory experience, are generally less likely to "bind" source features to an item and to each other in memory (i.e., the associative deficit). In two experiments, we tested whether memory for perceptual source features, independently or bound, is also the basis for older adults' remember responses or if their associative deficit leads them to base their responses on other types of information. The results suggest that retrieval of perceptual source features, individually or bound, forms the basis for younger but not for older adults' remember judgments even when the overall level of memory for perceptual sources is closely equated (Experiment 1) and when attention is explicitly directed to the source information at encoding (Experiment 2).     

Memory for age-face associations in younger and older adults: the role of generation and schematic support

Memory for ages of unfamiliar faces was examined in an associative memory task to determine whether generation as well as schematic support (cues from faces) would enhance later cued recall of the age information and reduce older adults' associative deficit. Participants studied faces and were either presented with the age or first had to guess before being shown the correct age. Later, participants were given a cued-recall test. Both younger and older adults exhibited associative memory enhancements from first generating the ages at encoding (a generation effect) despite the fact the initial generation was often inaccurate. Although older adults recalled fewer ages overall compared with younger adults, older adults were able to remember the age information for older faces equally as well as younger adults. However, when errors committed during generation were large and when schematic support was not available to support encoding and retrieval (when the age information was inconsistent given the cues from the face), generating was no longer beneficial for either older or younger adults. Thus, although older adults display an associative deficit when remembering specific age-face associations, this can be reduced through the use of prior knowledge and generation at encoding.     

Paying attention to binding: Further studies assessing the role of reduced attentional resources in the associative deficit of older adults

The present experiments investigated whether the observed associative deficit in older adults' episodic memory is mediated by a reduction of attentional resources. Using a dual-task procedure, younger and older participants studied lists of word pairs either under full attention or while performing a concurrent task. Both experiments showed that dividing attention did not cause a greater impairment to memory for associations than to memory for items in either age group. Furthermore, an analysis of concurrent task performance revealed that older adults' attentional costs for both learning and binding items were not larger than for learning items alone, relative to younger adults. These data provide support for a multicausal interpretation of older adults' memory deficits in which common, depleted attentional resources may be a mechanism that reduces memory for components of an episode in both older and younger adults under divided attention at encoding. In addition, older adults have a unique deficit in memory for the associations between the components, which does not seem to be resource dependent.     

Age-related differences in associative memory depend on the types of associations that are formed

ABSTRACT

Building on well-established findings of age-related decline in associative memory, we examined whether the magnitude of age differences depends on the types of associations that are formed. Specifically, because of predominant age-related changes in the hippocampus, we expected to find larger age differences in recognition of between-domain than within-domain associations. Twenty younger and 20 older healthy adults were given two associative recognition tests, using face–name and word–word pairs, that were matched for difficulty level. As hypothesized, a three-way interaction indicated that, relative to item recognition, age differences in associative recognition were greater for between-domain face–name associations than for within-domain word–word associations. This dissociation is consistent with the idea that the hippocampus plays a prominent role in binding information received from distal neocortical regions. The discussion focuses on the roles of recollection and familiarity in supporting associative memory as well as implications for the remediation of age-related memory decline.     

Adult age differences in memory for name-face associations: The effects of intentional and incidental learning

Previous studies have indicated that older adults have a special deficit in the encoding and retrieval of associations. The current study assessed this deficit using ecologically valid name-face pairs. In two experiments, younger and older participants learned a series of name-face pairs under intentional and incidental learning instructions, respectively, and were then tested for their recognition of the faces, the names, and the associations between the names and faces. Under incidental encoding conditions older adults' performance was uniformly lower than younger adults in all three tests, indicating age-related impairments in episodic memory representations. An age-related deficit specific to associations was found under intentional but not under incidental learning conditions, highlighting the importance of strategic associative processes and their decline in older adults. Separate analyses of hits and false alarms indicate that older adults' associative deficit originated from high false alarm rates in the associative test. Older adults' high false alarm rates potentially reflect their reduced ability to recollect the study-phase name-face pairs in the presence of intact familiarity with individual names and faces.