Age differences in context integration in memory

Destination Memory for Self-Related Information: When I Tell Elvis Presley about My Favorite Food

Destination memory, the ability to remember to whom information was previously delivered, has found to be influenced by social processing and social interactions. This memory has also been shown to be compromised in normal aging. Our paper investigated whether older adults would demonstrate better destination memory for self-related information than for general information.

METHODS

We asked younger adults and older adults to tell self-related information (e.g., "I like Chinese food") and semantic information (e.g., "the moon is smaller than the sun") to pictures of celebrities (e.g., Elvis Presley).

RESULTS

Analysis showed higher destination memory for self-related information than for semantic information in older adults and younger adults.

DISCUSSION

Older adults may draw on self-related information to improve memory and social interactions.

Preservation of long-term memory in older adults using a spaced learning paradigm

How much information we retain depends on type/schedule of training. It has been widely acknowledged that spaced learning is advantageous compared to massed learning for cognitively healthy young adults and should be considered an educational standard. Literature would suggest that the spacing effect is preserved with age, though it is unclear whether this effect translates to more ecologically valid concepts such as face-name associations, which are particularly susceptible to deterioration with age. Two experiments were conducted to investigate the effects of spacing across recent/remote retention intervals, and the effect of age on spacing in cognitively healthy older adults using the Face-Name Pairs task. Experiment 1 results suggest that the beneficial memory effects of spacing are particularly observed with long-term memory. Experiment 2 results suggest that older adults are impaired at learning compared to younger adults, that the spacing effect influences both older and younger adults at longer intervals, and that spaced-trained participants display similar forgetting patterns at longer intervals, irrespective of age. These results may have some implications regarding improving the conditions under which optimum retention occurs (namely, whether spacing is beneficial when learning ecologically valid concepts at longer intervals outside of laboratory settings), and may provide insight into the effect of age on our ability to learn and remember face-name associations.

Reducing age-related Memory Deficits: The Roles of Environmental Support and self-initiated Processing Activities

BACKGROUND

The notion that memory performance in older adults can be boosted by information provided by the environment was proposed by Craik (1983). The suggestion was that age-related memory deficits can be attenuated and sometimes even eliminated by a complementary combination of environmental support and consciously controlled self-initiated activities.

OBJECTIVE

The objective of the present article was to review the subsequent empirical and theoretical work on the topics of environmental support and self-initiated ativities as they relate to the effects of aging on human memory.

DISCUSSION

The notion of schematic support from the person's knowledge base is introduced and its relevance discussed. In addition, the effects of various types of support on encoding and retrieval processes in older adults are desribed, and the increasing theoretical importance of executive processes in reducing age-related memory deficits is discussed.

CONCLUSION

As one main conclusion, it is suggested that self-initiated control processes interact with both information provided by the environment and by the person's knowledge base to improve the effectiveness of encoding and retrieval processing in older adults.

Sleep quality and memory function in healthy ageing

OBJECTIVE

To study the relationship between sleep quality and memory in healthy ageing.

METHODS

The study included 99 people older than 50 years (69 women and 30 men; mean age, 68.74±7.18 years) with no associated diseases. Patients completed digital versions of the Word Learning and Visual Paired Associates tests and the Pittsburgh Sleep Quality Index questionnaire to assess the quality of sleep.

RESULTS

Pittsburgh Sleep Quality Index score was negatively correlated with Visual Paired Associates and Word Learning test performance. Performance in these 2 memory tests decreased in line with sleep quality. In addition, performance in Visual Paired Associates test was negatively correlated with subjective sleep quality, duration, and sleep disturbances. Performance on the Word Learning test was negatively correlated with subjective sleep quality and efficiency. Participants' sex showed a weak effect on Visual Paired Associates performance and sleep latency.

CONCLUSIONS

Medical professionals working with elderly patients should take into consideration the effect of poor sleep quality on memory. Cognitive impairment in these patients may be a manifestation of a neuroendocrine imbalance due to a disrupted circadian rhythm. More research is needed to prove this hypothesis.

EXPRESS: Age-related differences when searching in a real environment: The use of semantic contextual guidance and incidental object encoding

Visual search is a crucial, everyday activity that declines with aging. Here, referring to the environmental support account, we hypothesized that semantic contextual associations between the target and the neighboring objects (e.g., a teacup near a tea bag and a spoon), acting as external cues, may counteract this decline. Moreover, when searching for a target, viewers may encode information about the co-present distractor objects, by simply looking at them. In everyday life, where viewers often search for several targets within the same environment, such distractor objects may often become targets of future searches. Thus, we examined whether incidentally fixating a target during previous trials, when it was a distractor, may also modulate the impact of aging on search performance. We used everyday object arrays on tables in a real room, where healthy young and older adults had to search sequentially for multiple objects across different trials within the same array. We showed that search was quicker: (1) in young than older adults, (2) for targets surrounded by semantically associated objects than unassociated objects, but only in older adults, and (3) for incidentally fixated targets than for targets that were not fixated when they were distractors, with no differences between young and older adults. These results suggest that older viewers use both environmental support based on object semantic associations and object information incidentally encoded to enhance efficiency of real-world search, even in relatively simple environments. This reduces, but does not eliminate, search decline related to aging.

Sleep quality and memory function in healthy ageing

OBJECTIVE

To study the relationship between sleep quality and memory in healthy ageing.

METHODS

The study included 99 people older than 50 years (69 women and 30 men; mean age, 68.74 ± 7.18 years) with no associated diseases. Patients completed digital versions of the Word Learning (WL) and Visual Paired Associates (VPA) tests and the Pittsburgh Sleep Quality Index (PSQI) questionnaire to assess the quality of sleep.

RESULTS

PSQI score was negatively correlated with VPA and WL test performance. Performance in these 2 memory tests decreased in line with sleep quality. In addition, performance in VPA test was negatively correlated with subjective sleep quality, duration, and sleep disturbances. Performance on the WL test was negatively correlated with subjective sleep quality and efficiency. Participants' sex showed a weak effect on VPA performance and sleep latency.

CONCLUSIONS

Medical professionals working with elderly patients should take into consideration the effect of poor sleep quality on memory. Cognitive impairment in these patients may be a manifestation of a neuroendocrine imbalance due to a disrupted circadian rhythm. More research is needed to prove this hypothesis.

Episodic memory boosting in older adults: exploring the association of encoding strategies and physical activity

Background: Contextual memory is susceptible to the effects of aging and its impairment compromises episodic memories and quality of life in older adults. Objective: Compare the effects of cognitive support on incidental contextual memory free recall and recognition with a naturalistic experimental paradigm and explore the association of encoding strategies and physical activity on memory improvement. Methods: Subjects (≥60 years, n = 52) were assigned to one of two encoding conditions for the contextual memory task: with or without an incidental associative instruction to encourage association of an item to its spatial context. Immediate free recall and recognition tests were run to assess the encoding instruction efficiency. The association of memory performance and physical activity was analyzed using the scores on the International Physical Activity Questionnaire (IPAQ) to subdivide each experimental group into Low IPAQ (below median) and High IPAQ (above median) subgroups. Results: The associative encoding instruction increased contextual memory free recall and recognition, with greater effects on free recall. The most robust associations between physical activity and contextual memory were also seen on free recall, in which higher levels of physical activity corresponded to increased baseline performance (non-associative encoding condition) and greater improvement of memory by the encoding support (associative encoding condition). Conclusion: Cognitive support at encoding can improve contextual memory free recall and recognition, suggesting they are prone to rehabilitation. Moreover, higher physical activity levels were positively associated with encoding strategies on contextual memory improvement, increasing the availability of latent process-based components of the cognitive reserve.

The role of social attention in older adults’ ability to interpret naturalistic social scenes

Age-related differences on theory of mind (ToM) tasks are well established. However, the literature has been criticised for predominantly relying on tasks with poor ecological validity, and consequently it remains unclear whether these age differences extend to tasks with greater realism. In addition, we currently have a limited understanding of the factors that may contribute to age-related declines in ToM. To address these issues, we conducted two studies that assessed age differences in ToM using multimodal social scene stimuli. Study 1 also examined eye movements to assess whether biases in visual attention may be related to age-related difficulties in ToM, and Study 2 included an assessment of social attention (as indexed by biological motion perception) and working memory to assess whether these capacities may explain age difficulties in ToM. In both studies, the results showed that older adults performed worse than their younger counterparts on the ToM tasks, indicating that age-related difficulties in ToM extend to measures that more closely represent everyday social interactions. The eye-tracking data in Study 1 showed that older adults gazed less at the faces of protagonists in the social scenes compared with younger adults; however, these visual biases were not associated with ToM ability. Study 2 showed that older age was associated with a reduced ability to detect biological motion cues, and this mediated age-related variance in ToM ability. These findings are discussed in relation to competing theoretical frameworks of ageing that predict either improvements or declines in ToM with age.

Visual Acuity does not Moderate Effect Sizes of Higher-Level Cognitive Tasks

BACKGROUND/STUDY CONTEXT

Declining visual capacities in older adults have been posited as a driving force behind adult age differences in higher-order cognitive functions (e.g., the "common cause" hypothesis of Lindenberger & Baltes, 1994, Psychology and Aging, 9, 339-355). McGowan, Patterson, and Jordan (2013, Experimental Aging Research, 39, 70-79) also found that a surprisingly large number of published cognitive aging studies failed to include adequate measures of visual acuity. However, a recent meta-analysis of three studies (La Fleur and Salthouse, 2014, Psychonomic Bulletin & Review, 21, 1202-1208) failed to find evidence that visual acuity moderated or mediated age differences in higher-level cognitive processes. In order to provide a more extensive test of whether visual acuity moderates age differences in higher-level cognitive processes, we conducted a more extensive meta-analysis of topic.

METHODS

Using results from 456 studies, we calculated effect sizes for the main effect of age across four cognitive domains (attention, executive function, memory, and perception/language) separately for five levels of visual acuity criteria (no criteria, undisclosed criteria, self-reported acuity, 20/80-20/31, and 20/30 or better).

RESULTS

As expected, age had a significant effect on each cognitive domain. However, these age effects did not further differ as a function of visual acuity criteria.

CONCLUSION

The current meta-analytic, cross-sectional results suggest that visual acuity is not significantly related to age group differences in higher-level cognitive performance-thereby replicating La Fleur and Salthouse (2014). Further efforts are needed to determine whether other measures of visual functioning (e.g., contrast sensitivity, luminance) affect age differences in cognitive functioning.

What you know can influence what you are going to know (especially for older adults)

Stimuli related to an individual’s knowledge/experience are often more memorable than abstract stimuli, particularly for older adults. This has been found when material that is congruent with knowledge is contrasted with material that is incongruent with knowledge, but there is little research on a possible graded effect of congruency. The present study manipulated the degree of congruency of study material with participants’ knowledge. Young and older participants associated two famous names to nonfamous faces, where the similarity between the nonfamous faces and the real famous individuals varied. These associations were incrementally easier to remember as the name–face combinations became more congruent with prior knowledge, demonstrating a graded congruency effect, as opposed to an effect based simply on the presence or absence of associations to prior knowledge. Older adults tended to show greater susceptibility to the effect than young adults, with a significant age difference for extreme stimuli, in line with previous literature showing that schematic support in memory tasks particularly benefits older adults.

When does prior knowledge disproportionately benefit older adults' memory?

Material consistent with knowledge/experience is generally more memorable than material inconsistent with knowledge/experience – an effect that can be more extreme in older adults. Four experiments investigated knowledge effects on memory with young and older adults. Memory for familiar and unfamiliar proverbs (Experiment 1) and for common and uncommon scenes (Experiment 2) showed similar knowledge effects across age groups. Memory for person-consistent and person-neutral actions (Experiment 3) showed a greater benefit of prior knowledge in older adults. For cued recall of related and unrelated word pairs (Experiment 4), older adults benefited more from prior knowledge only when it provided uniquely useful additional information beyond the episodic association itself. The current data and literature suggest that prior knowledge has the age-dissociable mnemonic properties of (1) improving memory for the episodes themselves (age invariant), and (2) providing conceptual information about the tasks/stimuli extrinsically to the actual episodic memory (particularly aiding older adults).

Antimnemonic effects of schemas in young and older adults

Schema-consistent material that is aligned with an individual’s knowledge and experience is typically more memorable than abstract material. This effect is often more extreme in older adults and schema use can alleviate age deficits in memory. In three experiments, young and older adults completed memory tasks where the availability of schematic information was manipulated. Specifying nonobvious relations between to-be-remembered word pairs paradoxically hindered memory (Experiment 1). Highlighting relations within mixed lists of related and unrelated word pairs had no effect on memory for those pairs (Experiment 2). This occurred even though related word pairs were recalled better than unrelated word pairs, particularly for older adults. Revealing a schematic context in a memory task with abstract image segments also hindered memory performance, particularly for older adults (Experiment 3). The data show that processing schematic information can come with costs that offset mnemonic benefits associated with schema-consistent stimuli.

Neural correlates of local contextual processing across stimulus modalities and patient populations

The objective of the current review is to integrate information from a series of studies, employing a paradigm that evaluates local contextual processing using electrophysiological measures. Collectively these studies provide an overview of how utilization of predictive context changes as a function of stimulus modality and across different patient populations, as well as the networks that may be critical for this function. The following aspects of local contextual processing will be discussed and reviewed: (i) the correlates associated with contextual processing that have been identified in healthy adults, (ii) stimulus modality effects, (iii) specific alterations and deficits of local contextual processing in aging and across different neurological and psychiatric patient populations, including patients with prefrontal cortex lesions, Parkinson's disease, schizophrenia, and major depressive disorder, (iv) the potential for utilizing the correlates of local context as biomarkers for frontal cognitive dysfunction and (v) the role of frontal networks in the processing of contextual information. Overall findings show that behavioral and neural correlates associated with processing of local context are comparable across stimulus modalities, but show specific alterations in aging and across different neurological and psychiatric disorders.

How does it STAC up? Revisiting the scaffolding theory of aging and cognition

"The Scaffolding Theory of Aging and Cognition (STAC)", proposed in 2009, is a conceptual model of cognitive aging that integrated evidence from structural and functional neuroimaging to explain how the combined effects of adverse and compensatory neural processes produce varying levels of cognitive function. The model made clear and testable predictions about how different brain variables, both structural and functional, were related to cognitive function, focusing on the core construct of compensatory scaffolding. The present paper provides a revised model that integrates new evidence about the aging brain that has emerged since STAC was published 5 years ago. Unlike the original STAC model, STAC-r incorporates life-course factors that serve to enhance or deplete neural resources, thereby influencing the developmental course of brain structure and function, as well as cognition, over time. Life-course factors also influence compensatory processes that are engaged to meet cognitive challenge, and to ameliorate the adverse effects of structural and functional decline. The revised model is discussed in relation to recent lifespan and longitudinal data as well as emerging evidence about the effects of training interventions. STAC-r goes beyond the previous model by combining a life-span approach with a life-course approach to understand and predict cognitive status and rate of cognitive change over time.

Everyday memory strategies for medication adherence

The need to manage chronic diseases and multiple medications increases for many older adults. Older adults are aware of memory declines and incorporate compensatory techniques. Everyday memory strategies used to support medication adherence were investigated. A survey distributed to 2000 households in the Atlanta metropolitan area yielded a 19.9% response rate including 354 older adults, aged 60-80 years. Older adults reported forgetting to take their medications, more so as their activity deviated from normal routines, such as unexpected activities. The majority of older adults endorsed at least two compensatory strategies, which they perceived to be more helpful in normal routines. Compensatory strategies were associated with higher education, more medications, having concern, and self-efficacy to take medications. As memory changes, older adults rely on multiple cues, and perceive reliance on multiple cues to be helpful. These data have implications for the design and successful implementation of medication reminder systems and interventions.

Age-related differences according to the associative deficit and the environmental support hypotheses: an application of the formal charm associative memory model

BACKGROUND/STUDY CONTEXT: According to both the associative deficit hypothesis (ADH; Naveh-Benjamin, 2000 , Journal of Experimental Psychology: Learning, Memory, and Cognition, 26, 1170-1187) and the environmental support hypothesis (ESH; Craik, 1983 , Philosophical Transactions of the Royal Society of London Series B, 302, 354-359), memory decline with aging can be seen as an impairment of the self-initiated associative memory processes such that supportive encoding and/or retrieval can reduce age-related differences. A formalization of relationships between the ADH and ESH was investigated using the distributed memory model "CHARM" (Composite Holographic Associative Recall-Recognition Model; Metcalfe, 1982 , Psychological Review, 89, 627-661; Metcalfe, 1991 , Psychological Review, 98, 529-543).

METHODS

Empirical data were collected in young and elderly participants on cued recall and recognition tests according to both the level of processing (LOP: phonetic vs. semantic tasks) and the self-generated cueing (elaboration effect: provided vs. self-generated cue) manipulation. These data were compared with those from CHARM simulations that were designed to evaluate the impact of deteriorated associative processes (i.e., ADH) and the role of LOP and elaboration effects (i.e., ESH) in memory performance.

RESULTS

The simulated data were largely consistent with the empirical data, showing that the impairment of associative processes in the CHARM model was accompanied by an increased need for environmental support at encoding (interaction between age, LOP, and elaboration) to reduce memory decline in cued recall tasks, which is somewhat observed in the recognition scores.

CONCLUSION

The overall results from CHARM simulations are in accordance with both the ADH and ESH hypotheses and provide discussion on the formal connections between these two main aging explanations.

The role of perceptual information in familiarity-based scene recognition

A method to analyze the role of familiarity in recognizing pictures of everyday scenes is introduced. The idea is to manipulate two within-subjects conditions: an experimental condition where the scenes repeat perceptual information (e.g. buildings and/or vehicles) and a control condition. The results show the two conditions did not differ in terms of hit rates, but in the experimental condition there were significantly fewer false alarms, yielding better results, which supports the findings of past research studies that have used verbal materials. This perceptual facilitation was maintained throughout a week-long retention interval. Finally, a detailed analysis of this facilitation shows it was due to a significant reduction in false alarms on know judgments, emphasizing familiarity's role in explaining this effect.

Context processing in aging: older mice are impaired in renewal of extinguished fear

Fear conditioning, extinction, and renewal were evaluated in adult (6-month-old) and aging (17-month-old) male C57Bl/6 mice. Mice were subjected to five tone-shock trials and later exposed to 150 tone-alone trials. Thereafter, all mice showed little fear in the extinction context. Adult mice demonstrated return of fear in a distinct context (renewal) but aging mice did not. Aging mice showed normal shock sensitivity, tone fear learning, and extinction. Aging mice thus exhibited a very selective deficit in the contextual gating of extinguished fear. This contextual gating deficit may reflect age-related pathology in the hippocampus and prefrontal cortex.

What do we know about aging and spatial cognition? Reviews and perspectives

In order to cope with normal cognitive aging we must understand the patterns and neurofunctional underpinnings of cognitive and behavioral changes throughout adulthood. In this review, we summarize recent advances in our understanding of age-related behavioral differences and changes in brain structure throughout the spatial domain. Although spatial cognition is critically important to everyday life, few studies have examined the relationship between this cognitive function and neural changes in the aged brain. Thus, spatial cognition is considered a key area in which the cognitive neuroscience of aging may expand in the near future. The first section of this review examines the methodologies and studies used to assess differences in spatial cognition during normal cognitive aging in animals and humans. We then relate how each domain of spatial cognition (e.g., visuospatial perception, mental imagery, memory and navigation) is affected by the aging process, and discuss possible links with changes in neural mechanisms. Lastly, we address putative links among the age-related deterioration patterns of the various spatial domains and make suggestions for future research.

Reduced specificity of hippocampal and posterior ventrolateral prefrontal activity during relational retrieval in normal aging

Neuroimaging studies of episodic memory in young adults demonstrate greater functional neural activity in ventrolateral pFC and hippocampus during retrieval of relational information as compared with item information. We tested the hypothesis that healthy older adults--individuals who exhibit behavioral declines in relational memory--would show reduced specificity of ventrolateral prefrontal and hippocampal regions during relational retrieval. At study, participants viewed two nouns and were instructed to covertly generate a sentence that related the words. At retrieval, fMRIs were acquired during item and relational memory tasks. In the relational task, participants indicated whether the two words were previously seen together. In the item task, participants indicated whether both items of a pair were previously seen. In young adults, left posterior ventrolateral pFC and bilateral hippocampal activity was modulated by the extent to which the retrieval task elicited relational processing. In older adults, activity in these regions was equivalent for item and relational memory conditions, suggesting a reduction in ventrolateral pFC and hippocampal specificity with normal aging.

Bringing an Ecological Perspective to the Study of Aging and Recognition of Emotional Facial Expressions: Past, Current, and Future Methods

Older adults perform worse on traditional tests of emotion recognition accuracy than do young adults. In this paper, we review descriptive research to date on age differences in emotion recognition from facial expressions, as well as the primary theoretical frameworks that have been offered to explain these patterns. We propose that this is an area of inquiry that would benefit from an ecological approach in which contextual elements are more explicitly considered and reflected in experimental methods. Use of dynamic displays and examination of specific cues to accuracy, for example, may reveal more nuanced age-related patterns and may suggest heretofore unexplored underlying mechanisms.

Differential age effects for implicit and explicit conceptual associative memory

Older adults show disproportionate declines in explicit memory for associative relative to item information. However, the source of these declines is still uncertain. One explanation is a generalized impairment in the processing of associative information. A second explanation is a more specialized impairment in the strategic, effortful recollection of associative information, leaving less effortful forms of associative retrieval preserved. Assessing implicit memory of new associations is a way to distinguish between these viewpoints. To date, mixed findings have emerged from studies of associative priming in aging. One factor that may account for the variability is whether the manipulations inadvertently involve strategic, explicit processes. In two experiments we present a novel paradigm of conceptual associative priming in which subjects make speeded associative judgments about unrelated objects. Using a size classification task, Experiment 1 showed equivalent associative priming between young and older adults. Experiment 2 generalized the results of Experiment 1 to an inside/outside classification task, while replicating the typical age-related impairment in associative but not item recognition. Taken together, the findings support the viewpoint that older adults can incidentally encode and retrieve new meaningful associations despite difficulty with the intentional recollection of the same information.

Contemporary review 2009: cognitive aging

This article addresses key topics in cognitive aging, intending to provide the reader with a brief overview of the current state of research in this growing, multidisciplinary field. A summary of the physiological changes in the aging brain is provided as well as a review of variables that influence cognitive abilities in older age. Normal aging differentially affects various aspects of cognition, and specific changes within various domains such as attention, executive functioning, and memory are discussed. Various theories have been proposed to account for the cognitive changes that accompany normal aging, and a brief examination of these theories is presented in the context of these domain-specific changes.

Does believing in "use it or lose it" relate to self-rated memory control, strategy use, and recall?

After an oral free recall task, participants were interviewed about their memory. Despite reporting similar levels of perceived personal control over memory, older and young adults differed in the means in which they believed memory could be controlled. Older adults cited health and wellness practices and exercising memory, consistent with a "use it or lose it" belief system, more often than young adults who were more likely to mention metacognition and flexible strategy use as means of memory control. Young adults reported using more effective relational strategies during study for a free recall test. Use of relational strategies predicted recall in both age groups, but did not materially affect age differences in performance. Metacognitive beliefs, including implicit theories about aging and memory decline, memory self-concept, and perceived control over memory functioning, did not systematically correlate with strategy use or recall.

Age effects on wayfinding and route learning skills

While existing evidence suggests that older adults have compromised spatial navigation abilities, the effects of age on specific aspects of navigational skill are less well specified. The current study examined age effects on spatial navigation abilities considering the multiple cognitive and neural factors that contribute to successful navigation. Young and older adults completed wayfinding and route learning tasks in a virtual environment and aspects of environmental knowledge were assessed. Prefrontal, caudate and hippocampal volumes were obtained in a subset of older adults. Age differences were observed in both wayfinding and route learning. For wayfinding, there were age effects in recalling landmarks, and recognizing environmental scenes. In the route learning condition, older adults evidenced difficulty with the location, temporal order and directional information of landmarks. In both conditions, there was evidence of age-related differences in the acquisition of configural knowledge. Wayfinding was associated with the hippocampus whereas route learning was associated with the caudate nucleus. These results provide indications of specific aspects of navigational learning that may contribute to age-related declines and potential neural substrates.

The impact of increased relational encoding demands on frontal and hippocampal function in older adults

In the present study, we manipulated the cognitive effort in an associative encoding task using functional magnetic resonance imaging (fMRI). Older and younger adults were presented with two objects that were either semantically related or unrelated, and were required to form a relationship between the items. Both groups self-reported greater difficulty in completing the unrelated associative encoding task providing independent evidence of the associative difficulty manipulation. On both the low and high difficulty tasks, older adults showed a typical pattern of increased right inferior frontal recruitment relative to younger adults. Of particular interest was the finding that both groups showed increased activation as task difficulty increased in the left inferior frontal gyrus and left hippocampus. Overall, the results suggest that the aging brain is characterized by greater prefrontal processing, but that as cognitive demand increases, the networks used by older and younger adults are the largely the same.

Electrophysiological evidence for aging effects on local contextual processing

We used event-related potentials to investigate how aging affects local contextual processing. Local context was defined as the occurrence of a short predictive series of visual stimuli before delivery of a target event. Stimuli were presented to either the left or right visual field and consisted of 15% targets (downward facing triangle) and 85% of equal numbers of three types of standards (triangles facing left, upwards and right). Recording blocks consisted of targets preceded by either randomized sequences of standards or by sequences including a three-standard predictive sequence signaling the occurrence of a subsequent target event. Subjects pressed a button in response to targets. Predictive local context affected target detection by reducing the duration of stimulus evaluation compared to detection of non-predictive random targets comparably for both young and older adults, as shown by a P3b latency shift. The peak of an earlier latency context positivity, which was seen only in the predicted compared to the random target condition, was prolonged in the older population compared to young adults. Finally, older subjects elicited a late sustained positivity in the predictive condition, not seen in the younger subjects. Taken together, these findings suggest that local contextual effects on target detection processes are altered with age.

Generation, intentionality of processing at encoding and retrieval, and age-related associative deficits

This research tested age-related differences in the retrieval of self-generated new associations under conditions that required intentional or incidental processing. Under intentional or incidental encoding conditions, young and older adults generated new associations by producing a response to a two-letter stem paired with a cue/prime word (e.g., throne-mo_). Memory for these new associations was tested under intentional or incidental retrieval conditions by pairing the word stem with the previous cue/prime word, its homophone partner, or a prime/cue not previously presented. Results indicated equivalent priming and cueing effects for both age groups in all conditions. These results suggest that generation of new associations can eliminate age-related associative deficits, even under intentional encoding and retrieval conditions that typically disadvantage older adults.

Effects of Aging on Associative Memory for Related and Unrelated Pictures

Associative memory deficits are pervasive with age. Memory for complex pictures, however, also seems to require the association of several scene elements into one representation, but picture memory is often age-invariant. We speculated that the natural relationships contained in pictures may explain this distinction and that memory for scenes with unusual novel relationships would be affected with aging. In three experiments, we found that, counter to our predictions, the relatedness of scene elements exerted little influence on picture memory and did not differentially affect older compared to younger adults. These data suggest that the semantically rich associations contained in pictures need not rely on prior knowledge and experiences in order to support age-invariant picture memory. Our results indicate that associative memory for complex pictures may differ from memory for inter-item associations, which may be more affected by aging.

Effects of aging on the neural correlates of successful item and source memory encoding

To investigate the neural basis of age-related source memory (SM) deficits, young and older adults were scanned with fMRI while encoding faces, scenes, and face-scene pairs. Successful encoding activity was identified by comparing encoding activity for subsequently remembered versus forgotten items or pairs. Age deficits in successful encoding activity in hippocampal and prefrontal regions were more pronounced for SM (pairs) as compared with item memory (faces and scenes). Age-related reductions were also found in regions specialized in processing faces (fusiform face area) and scenes (parahippocampal place area), but these reductions were similar for item and SM. Functional connectivity between the hippocampus and the rest of the brain was also affected by aging; whereas connections with posterior cortices were weaker in older adults, connections with anterior cortices, including prefrontal regions, were stronger in older adults. Taken together, the results provide a link between SM deficits in older adults and reduced recruitment of hippocampal and prefrontal regions during encoding. The functional connectivity findings are consistent with a posterior-anterior shift with aging previously reported in several cognitive domains and linked to functional compensation.

Environmental support: an integrative framework

OBJECTIVE

In this qualitative review, we develop an integrative framework to bring coherence to the concept of environmental support (ES) in the fields of human factors and cognitive aging.

BACKGROUND

The ES hypothesis, originally formulated to explain effects of retrieval support on age-related differences in memory by reducing need for self-initiated processing, has been applied to many domains, such that the concept now encompasses many manipulations and measures. We developed a framework in which different types of ES share a common function (external support of performance) but differ in how this function is accomplished. ES improves performance by reducing task demands on mental resources or promoting effective use of resources. Previous reviews show that ES can decrease age-related differences in performance (more benefit for older adults), provide equal benefit, or increase differences (more benefit for younger adults). We proposed that the outcome will depend on properties of the ES, task, and person.

METHOD

We applied our framework to the domains of language comprehension and human-computer interaction, selecting studies representative of differing outcomes for ES.

RESULTS

In both domains, we found that outcomes depended on ES, task, and person. Age differences were more likely to be reduced by ES that imposed minimal prerequisites for use and targeted processes that needed support.

CONCLUSION

Our review helps refine the ES concept by identifying conditions under which age differences in performance are reduced or magnified by ES.

APPLICATIONS

The framework provides guidance for human factors practitioners to design tasks and environments for older adults.

Generation and associative encoding in young and old adults: the effect of the strength of association between cues and targets on a cued recall task

The generation effect (i.e., better recall of the generated items than the read items) was investigated with a between-list design in young and elderly participants. The generation task difficulty was manipulated by varying the strength of association between cues and targets. Overall, strong associates were better recalled than weak associates. However, the results showed different generation effect patterns according to strength of association and age, with a greater generation effect for weak associates in younger adults only. These findings suggest that generating weak associates leads to more elaborated encoding, but that elderly adults cannot use this elaborated encoding as well as younger adults to recall the target words at test.

Improvement of contextual memory by S 24795 in aged mice: comparison with memantine

RESULTS

In comparison with 5-month-old mice, 18- to 19-month-old mice exhibited a severe and specific memory impairment in a contextual serial discrimination (CSD) task involving the learning and remembering of two successive spatial discriminations carried out on two distinct floors. This impairment was specific, as spatial memory, simultaneously tested on a simple discrimination (SD) task, was not affected in these aged mice. This deficit was completely reversed by 9-day per os administration of S 24795, a partial agonist of alpha 7 nicotinic receptors, at either 0.3 or 1.0 mg/kg. Memantine, an NMDA receptor antagonist, also had a memory-enhancing effect at a dose of 3.0 mg/kg, but not at 0.3 mg/kg.

CONCLUSIONS

The memory-enhancing effect of S 24795 was due to a strong enhancement of contextual memory as indicated by a decrease in interference rate, whereas memantine enhanced spatial/semantic memory. S 24795 was more effective than memantine and also appears to be more specific to flexible forms of memory, one of the first cognitive domains (i.e. episodic memory) affected in Alzheimer's disease.

Improvement of episodic contextual memory by S 18986 in middle-aged mice: comparison with donepezil

INTRODUCTION

This study compared the effects of S 18986, a positive allosteric modulator of alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)-type glutamate receptors, to those of donepezil a cholinesterase inhibitor on memory impairments induced by ageing in a contextual serial discrimination (CSD) task in middle-aged mice.

MATERIALS AND METHODS

The CSD task involved the learning of two consecutive discriminations in a four-hole board, each performed on two different floors. This model has been developed to study simultaneously different forms of memory in mice (i.e., episodic-like vs semantic-like forms of memory). We showed that placebo-middle-aged mice (14-15 months old) and placebo-aged subjects (19-20 months old) exhibited a severe memory deficit for the first but not the second discrimination, which was due to an increase in interference, as compared with placebo-treated young mice (5 months old). Middle-aged mice were given (9 days) per os administration of either donepezil, S 18986, or placebo.

RESULTS AND DISCUSSION

Both 0.3 mg/kg donepezil and 0.1 mg/kg S 18986 reversed the deficit of middle-aged mice through a significant increase in contextually correct responses and in parallel a tendency to reduce interfering responses.

CONCLUSION

Overall, S 18986 emerges as having a beneficial impact on contextual memory processes in middle-aged mice.

Design your own memory strategies! Self-generated strategy training versus mnemonic training in old age: An 8-month follow-up

We examined maintenance effects following training in a self-generated strategy versus a mnemonic strategy, designed to improve recall of four-digit numbers in older adults. This was accomplished by reassessing participants from a previous study eight months after completion of training. A control group that received no training was also included. The results showed that both training groups maintained training-related gains in number recall performance eight months later in a criterion task providing cognitive support. However, when no support was provided, number recall performance for the mnemonic group dropped slightly whereas performance for the self-generated strategy group improved. The control group maintained performance across assessments. These data indicate the numerical memory training may result in long-term effects in older adults and that, under some conditions, practising one's own memory strategies may have advantages over mnemonic training in old age.

Contextual interference in recognition memory with age

Previous behavioral research suggests that although elderly adults' memory benefits from supportive context, misleading or irrelevant contexts produce greater interference. In the present study, we use event-related fMRI to investigate age differences when processing contextual information to make recognition judgments. Twenty-one young and twenty elderly incidentally encoded pictures of objects presented in meaningful contexts, and completed a memory test for the objects presented in identical or novel contexts. Elderly committed more false alarms than young when novel objects were presented in familiar, but task-irrelevant, contexts. Elderly showed reduced engagement of bilateral dorsolateral prefrontal cortex and anterior cingulate relative to young, reflecting disruption of a cognitive control network for processing context with age. Disruption occurred for both high and low-performing elderly, suggesting that cognitive control deficits are pervasive with age. Despite showing disruption of the cognitive control network, high-performing elderly recruited additional middle and medial frontal regions that were not recruited by either low-performing elderly or young adults. This suggests that high-performing elderly may compensate for the disruption of the cognitive control network by recruiting additional frontal resources to overcome cognitive control deficits that affect recognition memory.

The Contribution of Mediator-Based Deficiencies to Age Differences in Associative Learning

Production, mediational, and utilization deficiencies, which describe how strategy use may contribute to developmental trends in episodic memory, have been intensively investigated. Using a mediator report-and-retrieval method, the authors present evidence concerning the degree to which 2 previously unexplored mediator-based deficits--retrieval and decoding deficiencies--account for age deficits in learning. During study, older and younger adults were instructed to use a strategy (imagery or sentence generation) to associate words within paired associates. They also reported each mediator and later attempted to retrieve each response and the mediator produced at study. Substantial deficits occurred in mediator recall, and small differences were observed in decoding mediators. Mediator recall also accounted for a substantial proportion of the age deficits in criterion recall independently of fluid or crystallized intelligence. Discussion focuses on mediator-based deficiencies and their implications for theories of age deficits in episodic memory.

Preserved spatial memory over brief intervals in older adults

Two studies compared young and older adults' memory for location information after brief intervals. Experiment 1 found that accuracy of intentional spatial memory for individual locations was similar in young and older participants for set sizes of 3 and 6. Both groups also encoded individual locations in relation to the larger configuration of locations. Experiment 2 showed that like young adults, older adults' latency to respond to a test probe in a letter working memory task was negatively influenced by spatial information that was irrelevant to the task. This interference effect indicated preserved incidental memory for spatial information in older adults. Together, these data suggest that initial encoding of spatial information for relatively small numbers of items is largely preserved in healthy older adults and that representations of spatial information persist over short intervals.

Age-related differences in the use of contextual information in recognition memory: a global matching approach

Age differences in the processing of contextual information were investigated using the Item, associated Context, and Ensemble (ICE) model (K. Murnane, M. P. Phelps, & K. Malmberg, 1999), a general global matching model of recognition memory. In two experiments, young and older adults studied words in environmental contexts and were tested in both the same and different contexts. Patterns of context effects for hit rate, false alarm rate, and d' suggest that older adults process associated context, but have difficulties integrating items and context into an ensemble. Thus, older adults appear to have a specific, rather than a general, deficit in processing contextual information. A deficiency in ensemble processing may be responsible for the prevalent finding that older adults show poorer recognition memory performance than young adults.

Age effect in recall performance according to the levels of processing, elaboration, and retrieval cues

The present study was conducted to investigate the incidence of several factors contributing to age-related memory decrement. Variables manipulated include quality (level of processing encoding conditions), the degree of effort and encoding quantitative elaboration (active/passive encoding conditions), and the influence of retrieval support (free-/cued recall conditions). In support of the environmental support hypothesis, middle-old and old subjects benefited more than young ones from cued recall in all the memory tests. Moreover, the results showed a differential (qualitative vs. quantitative) impairment of conceptual processing between the middle-old and the old-age groups. In the middle-olds, age differences were abolished by deep processing in old adults, age differences were attentuated only with deep and active processing associated with retrieval support. These gradual memory impairments are evaluated according to Mandler's model of memory (1979, In L. G. Nilsson [Ed.], Perspective in memory research. Hillsdale: Lawrence-Erlbaum), and the environmental support hypothesis is discussed in terms of the involvement of encoding and retrieval operations required by the memory task.