The applied value of collaborative memory research in aging: Behavioral and neural considerations

Our aim in this paper is to bring attention to the applied value of collaborative memory research in aging. At this time, much collaborative memory research focuses on the negative effects of collaboration in younger adults, and is primarily basic in nature. Here, we highlight the positive effects of collaboration that have received less attention, with a particular emphasis on the applied value of these effects in older adults. We first review studies to show that recalling in a group improves later individual recall and reduces memory errors in older adults. We then outline a four-step approach towards bridging laboratory and applied collaborative memory research, which involves: (1) complementing traditional paradigms with more ecologically valid paradigms, (2) evaluating these paradigms in applied settings, (3) adapting these paradigms for use with cognitively intact and cognitively impaired populations, and (4) modifying these paradigms to examine the neural systems that operate during collaborative recall.     

Prospective memory in young and older adults: The effects of ongoing-task load

ABSTRACT

Prospective memory involves remembering to perform intended actions in the future. Previous work with the multinomial model of event-based prospective memory indicated that adult age-related differences in prospective-memory performance were due to the prospective (not the retrospective) component of the task (Smith & Bayen, 2006 Smith, R. E. and Bayen, U. J. 2006. The source of age differences in event-based prospective memory: A multinomial modeling approach. Journal of Experimental Psychology: Learning, Memory, and Cognition, 32: 623–635. [Crossref], [PubMed], [Web of Science ®] , [Google Scholar], Journal of Experimental Psychology: Learning, Memory, and Cognition, 32, 623). However, ongoing-task performance was also lower in older adults in that study. In the current study with young and older adults, the difficulty of the ongoing task was manipulated by varying the number of colors per trial to create easier and harder versions of the ongoing task for each age group. The easier version included 2 colors per trial for older adults and 4 colors for young adults. The harder version included 4 colors for older adults and 6 colors for young adults. By adjusting the ongoing-task difficulty, older adults were able to perform the ongoing task as well or better than the young adults. Analyses with the multinomial model revealed that making the ongoing task easier for older adults (or more difficult for young adults) did not eliminate age-related differences in prospective-memory performance and the underlying prospective component.     

Primed word-fragment completion and successive memory test performance in normal aging

Young and old subjects were investigated to examine whether: the effects of priming are influenced by aging; there is independence between primed word-fragment completion and recognition performances; and the dependence between different tests is influenced by aging. A successive test paradigm was employed involving repeated assessment of to-be-remembered words by means of recognition and primed word-fragment completion. The results show that implicit memory declines with increasing age, and that correlations between different memory tests decrease with age. The outcome suggests that age-related memory decline involves several forms of memory, including primed word-fragment completion, and is reflected in correlations between measures of implicit and explicit memory.     

Influence of memory strategies on memory test performance: A study in healthy and pathological aging

ABSTRACT

The ability to generate memory strategies is a key factor in the performance of episodic memory tasks. Whether the ability to generate memory strategies exerts an influence in the performance of memory tests in the elderly population is still a matter of debate. Here we present results from an experimental memory task (Test of Memory Strategies, TMS), comprised of five lists of words starting from an incidental learning task, and four more lists which progressively gain in their external organization of the material, reducing the necessity of mobilizing complex memory strategies. TMS has been applied to four groups of elderly patients (amnestic Mild Cognitive Impairment – aMCI, multidomain (mMCI), and Vascular Cognitive Impairment – VCI and Depression) and a healthy aging group. In conditions with low organization of the material, the mMCI and VCI groups (both showing a greater executive function impairment) have shown lower performance. However, as the material was progressively organized, they improved their performance. The aMCI group showed similar performance to the control group at the lower level of external organization but did not improve performance in conditions with a high level of external organization. The mMCI and VCI groups showed lower performance on all TMS conditions compared with controls. Discriminant analysis revealed 90% sensitivity and specificity to differentiate between groups based on TMS conditions. These results indicate how executive functions influence performance on memory tasks in elderly subjects with different neuropsychological profiles.     

The effect of strategies and contexts on memory for movement patterns

Two experiments on memory for movement patterns examined possible motor aspects of this memory type. None of the experiments found any evidence for motor effects. The first experiment showed lower memory with induced motor strategies than with any of the other induced strategies. The second experiment demonstrated stronger context effects under retrieval than under encoding conditions. The results are discussed in terms of functional and structural conceptions of episodic short-term memory of motor information.     

Dissociative experience and mood-dependent memory

Amnesia is the main phenomenon in dissociative experiences. The present study investigated whether amnesia in participants with frequent dissociative experiences depended on state-dependent memory. Undergraduates scoring high (n=32) or low (n=32) on the Dissociative Experiences Scale Version-II (DES-II) participated in this experiment. Mood induction and a remember/know task were used in a typical mood-independent memory design. In the inconsistent mood state condition, participants in the high DES group showed decreased memory performance compared to the low DES group. These results were attributed to the recollection components of recognition and not to the familiarity component. Therefore we concluded that the normal population with highly frequent dissociative experiences showed strong state-dependent memory and had a memory bias in the recollection component of memory.     

A benefit of context reinstatement to recognition memory in aging: the role of familiarity processes

Reinstatement of encoding context facilitates memory for targets in young and older individuals (e.g., a word studied on a particular background scene is more likely to be remembered later if it is presented on the same rather than a different scene or no scene), yet older adults are typically inferior at recalling and recognizing target–context pairings. This study examined the mechanisms of the context effect in normal aging. Age differences in word recognition by context condition (original, switched, none, new), and the ability to explicitly remember target–context pairings were investigated using word–scene pairs (Experiment 1) and word–word pairs (Experiment 2). Both age groups benefited from context reinstatement in item recognition, although older adults were significantly worse than young adults at identifying original pairings and at discriminating between original and switched pairings. In Experiment 3, participants were given a three-alternative forced-choice recognition task that allowed older individuals to draw upon intact familiarity processes in selecting original pairings. Performance was age equivalent. Findings suggest that heightened familiarity associated with context reinstatement is useful for boosting recognition memory in aging.     

Differential time-dependent effects of emotion on recollective experience and memory for contextual information

Emotion has been suggested to slow forgetting via a mechanism that enhances memory consolidation. Here, we investigate whether this time dependent process influences the subjective experience of recollection as well as the ability to retrieve specific contextual details of the study event. To do so we examined recognition for emotional and neutral pictures at two retention intervals and collected remember/know reports and reports about the task that had been performed with the item during encoding. Recollective experience was enhanced for emotional compared to neutral photos after a 24-h delay, but not immediately after encoding. In contrast, memory for the task performed during encoding did not differ between emotional and neutral photos at either time point. The findings indicate that emotion slows the effects of forgetting on the recollective experience associated with studied events, without necessarily slowing the forgetting of specific contextual details of those events.     

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

Recall is typically better for emotional than for neutral stimuli. This enhancement is believed to rely on limbic regions. Memory is also better for neutral stimuli embedded in an emotional context. The neural substrate supporting this effect has not been thoroughly investigated but may include frontal lobe, as well as limbic circuits. Alzheimer's disease (AD) results in atrophy of limbic structures, whereas normal aging relatively spares limbic regions but affects prefrontal areas. The authors hypothesized that AD would reduce all enhancement effects, whereas aging would disproportionately affect enhancement based on emotional context. The results confirmed the authors' hypotheses: Young and older adults, but not AD patients, showed better memory for emotional versus neutral pictures and words. Older adults and AD patients showed no benefit from emotional context, whereas young adults remembered more items embedded in an emotional versus neutral context.     

The role of attention in the contextual enhancement of visual memory for natural scenes

The role of attention in memory for objects in natural scenes was investigated using a visual memory. In Experiment 1, participants were asked to memorize six cued (to be attended) objects in a natural scene, and were subsequently tested on one of the cued objects. Four types of test scene images were created by jumbling different sections in scene's background: Attended sections changed, unattended sections changed, both sections changed, and both unchanged. In Experiment 2, the procedure was the same as that of the jumble condition except that scenes to be memorized were also jumbled. Results showed that jumbling of attended sections reduced memory performance, whereas jumbling unattended sections did not, irrespective of the regularity of scene to be memorized. This finding suggests that attention plays an important role in mental construction of a natural scene representation, and leads to enhanced visual memory.     

The effect of spatial and nonspatial contextual information on visual object memory

Recent research has found visual object memory can be stored as part of a larger scene representation rather than independently of scene context. The present study examined how spatial and nonspatial contextual information modulate visual object memory. Two experiments tested participants’ visual memory by using a change detection task in which a target object's orientation was either the same as it appeared during initial viewing or changed. In addition, we examined the effect of spatial and nonspatial contextual manipulations on change detection performance. The results revealed that visual object representations can be maintained reliably after viewing arrays of objects. Moreover, change detection performance was significantly higher when either spatial or nonspatial contextual information remained the same in the test image. We concluded that while processing complex visual stimuli such as object arrays, visual object memory can be stored as part of a comprehensive scene representation, and both spatial and nonspatial contextual changes modulate visual memory retrieval and comparison.     

The role of memory for compounds in cue competition

Revisions of common associative learning models incorporate a within-compound association mechanism in order to explain retrospective cue competition effects (e.g., [Dickinson, A., & Burke, J. (1996). Within-compound associations mediate the retrospective revaluation of causality judgements. Quarterly Journal of Experimental Psychology, 49B, pp. 60-80.]). These models predict a correlation between memory for compounds (as a measure for the strength of within-compound associations) and retrospective cue competition but not forward cue competition. This was indeed found in a study of [Melchers, K. G., Lachnit, H., & Shanks, D. (2004). Within-compound associations in retrospective revaluation and in direct learning: A challenge for comparator theory. Quarterly Journal of Experimental Psychology, 57B, pp. 25-54.]. We argue that a higher-order reasoning account of causal learning can also explain the evidence for the role of within-compound associations in cue competition. Moreover, this account predicts that if making inferences during the learning stage is impeded, a correlation between memory for compounds and forward cue competition should be found as well. The results of a new study confirmed this prediction.     

Trade-offs in visual attention and the enhancement of memory specificity for positive and negative emotional stimuli

Emotional influences on memory can lead to trade-offs in memory for gist or detail and trade-offs in memory for central or peripheral aspects of an event. Attentional narrowing has often been proposed as a theoretical explanation for this pattern of findings with negative emotion. These trade-offs have been less extensively investigated with positive emotion. In three experiments, we investigate memory for specific visual details of positive and negative stimuli, examine central–peripheral trade-offs in memory, and assess the hypothesis that attentional narrowing contributes to emotional enhancement of memory specificity. We found that memory for details was enhanced by negative and positive emotion. Central–peripheral trade-offs were found in memory for negative emotional stimuli but not in memory for positive emotional stimuli. These trade-offs with negative emotion were associated with attentional narrowing at the time of encoding, as measured by eye movements. There were no attentional effects at the time of encoding found with positive emotional stimuli. Evidence was found for the attentional narrowing hypothesis of memory specificity and central–peripheral trade-offs in memory for negative emotional events. Alternative explanations for the positive emotional enhancement of memory specificity are required.     

Effects of context expectation on prospective memory performance among older and younger adults

This experiment examined the impact of context expectation on prospective memory (PM) performance among older and younger adults. Participants responded to PM target words embedded in an ongoing lexical decision task (LDT). Older and younger adults performed similarly on the PM task. Regardless of age, PM was significantly better for participants in the correct context expectation condition and significantly worse in the incorrect context expectation condition relative to participants who held no expectations about the context in which targets would appear. Participants’ LDT response latencies were used to assess cost of the PM task to the ongoing task. Latencies were discernibly longer in the LDT block where the PM targets were expected compared to the block where they were not expected. The findings provide new information about how context can be used to support PM aging and suggest that contextual information can be equally beneficial for older and younger adults.     

Stereotype activation, inhibition, and aging

This research explored age-related changes in drawing stereotypic inferences during the comprehension of narrative texts. Previous research suggests that declines in inhibitory function can lead older adults to rely more on stereotypes and be more prejudiced than younger adults, even in the face of a desire to be non-prejudiced. In two experiments reported here, younger and older adults read stories that allowed for stereotypic inferences. Older adults were less likely to inhibit stereotypic inferences as measured by recognition measures and lexical decision times. A third control experiment verified that the results of the lexical decision task were not due to a priori response biases for the specific target words. Overall, older adults were more likely to make and maintain stereotypic inferences than younger adults, potentially causing them to be more prejudiced than younger adults.     

Emotional stimuli exert parallel effects on attention and memory

Because emotional and neutral stimuli typically differ on non-emotional dimensions, it has been difficult to determine conclusively which factors underlie the ability of emotional stimuli to enhance immediate long-term memory. Here we induced arousal by varying participants' goals, a method that removes many potential confounds between emotional and non-emotional items. Hungry and sated participants encoded food and clothing images under divided attention conditions. Sated participants attended to and recalled food and clothing images equivalently. Hungry participants performed worse on the concurrent tone-discrimination task when they viewed food relative to clothing images, suggesting enhanced attention to food images, and they recalled more food than clothing images. A follow-up regression analysis of the factors predicting memory for individual pictures revealed that food images had parallel effects on attention and memory in hungry participants, so that enhanced attention to food images did not predict their enhanced memory. We suggest that immediate long-term memory for food is enhanced in the hungry state because hunger leads to more distinctive processing of food images rendering them more accessible during retrieval.     

Time of day affects implicit memory for unattended stimuli

We investigated whether circadian arousal affects perceptual priming as a function of whether stimuli were attended or ignored during learning. We tested 160 participants on- and off-peak with regards to their circadian arousal. In the study phase, they were presented with two superimposed pictures in different colours. They had to name the pictures of one colour while ignoring the others. In the test phase, they were presented with the same and randomly intermixed new pictures. Each picture was presented in black colour in a fragment completion task. Priming was measured as the difference in fragmentation level at which the pictures from the study phase were named compared to the new pictures. Priming was stronger for attended than ignored pictures. Time of day affected priming only for ignored pictures, with stronger priming effects off-peak than on-peak. Thus, circadian arousal seems to favour the encoding of unattended materials specifically at off-peak.     

Dissociated deficits of visuo-spatial memory in near space and navigational space: Evidence from brain-damaged patients and healthy older participants

ABSTRACT

Defects confined to spatial memory can severely affect a variety of daily life activities, such as remembering the location of objects or navigating the environment, until now the skills involved have been mostly assessed with regard to the visual domain using traditional pencil and paper tests. Our aim was to test the efficacy of a recently developed psychometric instrument (Walking Corsi Test: WalCT) to assess the specific contribution of spatial memory to the complex task of retrieving route knowledge. The WalCT is a 3×2.5-m version of the well-known Corsi Block-tapping Test (CBT), in which patients are required to memorize (and replicate) a sequence of body displacements. We assessed the ability of left and right brain-damaged patients, as well as healthy young and senior controls, to perform both the CBT and the WalCT. Results showed differences related to age in the healthy individuals and specific functional dissociations in the brain-damaged patients. The double dissociations found in this study demonstrate the importance of having a task able to detect navigational disorders, because virtual reality tasks are often much too difficult for aged brain-damaged patients to perform.     

Spatial distribution of attentional bias in visuo-spatial working memory following multiple cues

When attention is focused on one location, its spatial distribution depends on many factors, such as the distance between the attended location and the target location, the presence of visual meridians in between them, and the way, endogenous or exogenous, by which attention is oriented. However, it is not well known how attention distributes when more than one location is endogenously or exogenously cued, which was the focus of the current study. Furthermore, the distribution of attention has been manly investigated in perception. In the present study we faced this issue from a different perspective, by examining the spatial distribution of the attentional bias in visuo-spatial working memory (VSWM), when attention is oriented either exogenously or endogenously, i.e., after two peripheral vs. central symbolic cues (also manipulating cue–target predictability). Results indicated a systematic difference between endogenous and exogenous attention regarding the distribution of the attentional bias over VSWM. In fact, attentional bias following endogenous cues was affected by the presence of visual meridians and by the split of the attentional focus, converging in a unipolar attentional distribution, independently of cue–target predictability. On the other hand, when pulled by exogenous cues, attention distributed uni-modally or multi-modally depending on the distance between the cued locations, with larger effects for highly predictive cues. Results are discussed in terms of space-based, object-based and perceptual grouping mechanisms.