Age-related differences in immediate serial recall: dissociating chunk formation and capacity

Multivitamin Supplementation Improves Memory in Older Adults: A Randomized Clinical Trial

BACKGROUND

Maintenance of cognitive abilities is of critical importance to older adults, yet few effective strategies to slow cognitive decline currently exist. Multivitamin supplementation is used to promote general health; it is unclear whether it favorably affects cognition in older age.

OBJECTIVES

To examine the effect of daily multivitamin/multimineral supplementation on memory in older adults.

METHODS

The COcoa Supplement and Multivitamin Outcomes Study Web (COSMOS-Web) ancillary study (NCT04582617) included 3562 older adults. Participants were randomly assigned to a daily multivitamin supplement (Centrum Silver) or placebo and evaluated annually with an Internet-based battery of neuropsychological tests for 3 y. The prespecified primary outcome measure was change in episodic memory, operationally defined as immediate recall performance on the ModRey test, after 1 y of intervention. Secondary outcome measures included changes in episodic memory over 3 y of follow-up and changes in performance on neuropsychological tasks of novel object recognition and executive function over 3 y.

RESULTS

Compared with placebo, participants randomly assigned to multivitamin supplementation had significantly better ModRey immediate recall at 1 y, the primary endpoint (t(5889) = 2.25, P = 0.025), as well as across the 3 y of follow-up on average (t(5889) = 2.54, P = 0.011). Multivitamin supplementation had no significant effects on secondary outcomes. Based on cross-sectional analysis of the association between age and performance on the ModRey, we estimated that the effect of the multivitamin intervention improved memory performance above placebo by the equivalent of 3.1 y of age-related memory change.

CONCLUSIONS

Daily multivitamin supplementation, compared with placebo, improves memory in older adults. Multivitamin supplementation holds promise as a safe and accessible approach to maintaining cognitive health in older age. This trial was registered at clinicaltrials.gov as NCT04582617.

Beyond balance and mobility, contributions of cognitive function to falls in older adults with cardiovascular disease

Objectives:

Older adults with cardiovascular disease (CVD) are at risk for cognitive impairment. Cognitive function is associated with falls in older adults however it is unknown if a relationship exists between cognitive function and falls in CVD. The aim of this study was to examine the contributions of cognitive function on falls in older adults with CVD.

Methods:

A secondary analysis was performed on data from the Health and Retirement Study cohort 2010 (N=3413) of older adults with CVD. Group assignment was based on falls history (yes/no) within the two years prior to the survey. Demographic (age, education, gender, marital status), physical (strength, balance, physical activity, and mobility) and cognitive (immediate and delayed recall, orientation, semantic verbal fluency, numeracy) information was extracted to characterize the sample. Comparisons between groups were completed for all of these variables. Logistic regression was performed to examine associations between each of the cognitive variables and falls while controlling for age, gender, marital status, education, and BMI.

Results:

Demographic (age, gender, marital status, and education), physical (grip strength, tandem stance time, and gait speed), and cognitive (orientation, immediate and delayed recall) variables differed by falls history (p<0.05). After controlling for confounding, immediate recall was the only significant predictor of falls (OR=1.09, 95% CI=1.01-1.17) (Nagelkerke R²=0.037, χ²=35.14, p<0.05) with correctly classifying 65.9% of cases.

Conclusions:

In older adults with CVD, cognitive and physical functions are more impaired in those with a falls history. Screening for cognitive function, specifically immediate recall, should be a part of the management of falls in this population.

Skill acquisition as a function of age, hand and task difficulty: Interactions between cognition and action

Some activities can be meaningfully dichotomised as 'cognitive' or 'sensorimotor' in nature-but many cannot. This has radical implications for understanding activity limitation in disability. For example, older adults take longer to learn the serial order of a complex sequence but also exhibit slower, more variable and inaccurate motor performance. So is their impaired skill acquisition a cognitive or motor deficit? We modelled sequence learning as a process involving a limited capacity buffer (working memory), where reduced performance restricts the number of elements that can be stored. To test this model, we examined the relationship between motor performance and sequence learning. Experiment 1 established that older adults were worse at learning the serial order of a complex sequence. Experiment 2 found that participants showed impaired sequence learning when the non-preferred hand was used. Experiment 3 confirmed that serial order learning is impaired when motor demands increase (as the model predicted). These results can be captured by reinforcement learning frameworks which suggest sequence learning will be constrained both by an individual's sensorimotor ability and cognitive capacity.

Self-initiated spatial working memory in young and older adults

The age-related decline in working memory (WM) has been studied extensively. Yet, research has focused mainly on one aspect of memory, in which older adults memorised information provided to them, neglecting the frequent everyday behaviour in which memory is self-initiated (SI), meaning that individuals memorise information they selected themselves. The present study used a modified spatial span task in which young and older adults memorised spatial sequences they constructed themselves, or random sequences provided to them. The results revealed that young and older adults carefully planned and constructed structured spatial sequences, by minimising distances between successive locations, and by selecting sequences with fewer path crossings and with more linear shapes. Older adults constructed sequences that were even more structured in some aspects. Young and older adults benefited from self-initiation to the same extent, showing similar age-related declines in SI and provided spatial WM. Overall, the study shows that older adults have access to metacognitive knowledge on the structure of efficient WM representations that benefit accuracy, and shows that older adults can use strategic encoding processes efficiently when encoding is SI. More generally, SI WM explores an important aspect of behaviour, demonstrating how older adults shape their environment to facilitate cognitive functioning.

Developmental Abilities to Form Chunks in Immediate Memory and Its Non-Relationship to Span Development

Both adults and children –by the time they are 2–3 years old– have a general ability to recode information to increase memory efficiency. This paper aims to evaluate the ability of untrained children aged 6–10 years old to deploy such a recoding process in immediate memory. A large sample of 374 children were given a task of immediate serial report based on SIMON®, a classic memory game made of four colored buttons (red, green, yellow, blue) requiring players to reproduce a sequence of colors within which repetitions eventually occur. It was hypothesized that a primitive ability across all ages (since theoretically already available in toddlers) to detect redundancies allows the span to increase whenever information can be recoded on the fly. The chunkable condition prompted the formation of chunks based on the perceived structure of color repetition within to-be-recalled sequences of colors. Our result shows a similar linear improvement of memory span with age for both chunkable and non-chunkable conditions. The amount of information retained in immediate memory systematically increased for the groupable sequences across all age groups, independently of the average age-group span that was measured on sequences that contained fewer repetitions. This result shows that chunking gives young children an equal benefit as older children. We discuss the role of recoding in the expansion of capacity in immediate memory and the potential role of data compression in the formation of chunks in long-term memory.

Retrospective cues based on object features improve visual working memory performance in older adults

Research with younger adults has shown that retrospective cues can be used to orient top-down attention toward relevant items in working memory. We examined whether older adults could take advantage of these cues to improve memory performance. Younger and older adults were presented with visual arrays of five colored shapes; during maintenance, participants were presented either with an informative cue based on an object feature (here, object shape or color) that would be probed, or with an uninformative, neutral cue. Although older adults were less accurate overall, both age groups benefited from the presentation of an informative, feature-based cue relative to a neutral cue. Surprisingly, we also observed differences in the effectiveness of shape versus color cues and their effects upon post-cue memory load. These results suggest that older adults can use top-down attention to remove irrelevant items from visual working memory, provided that task-relevant features function as cues.

Undivided attention improves postoperative anesthesia handover recall

BACKGROUND

For years, undivided attention during the presurgical "timeout" has been utilized as a precaution to ensure patient safety. The information relayed during the timeout is presented in a confirmatory nature rather than a delegation of new information. However, it is a standard of practice in which all members of the operating theater provide their full and undivided attention. Standards of patient care should be contiguous throughout the preoperative, perioperative, and postoperative stages of surgery. In this manner, it is expected that the same undivided attention afforded during the timeout should be maintained when transferring the patient to the postanesthesia care unit.

METHODS

In this study, information was collected regarding handover of information during the transfer status postsurgical procedures. Data were collected via observing interactions between the anesthesiologist and the nurse during verbal patient transfers.

RESULTS

This study demonstrated that the presence of undivided attention during the handover of a surgical patient in the postanesthesia care unit has a direct correlation with improved recall of the information discussed during handover.

CONCLUSION

Focus is on the quantity of information that can be recalled by the transferring nurse, and whether or not undivided attention affects the outcome. Analysis focuses on suggestions to better improve patient safety and recovery when being transferred in an anesthetic setting. The practice of patient handover should be standardized to better improve the safety and quality of medical care.

Older adults do not notice their names: a new twist to a classic attention task

Although working memory spans are, on average, lower for older adults than young adults, we demonstrate in 5 experiments a way in which older adults paradoxically resemble higher capacity young adults. Specifically, in a selective-listening task, older adults almost always failed to notice their names presented in an unattended channel. This is an exaggeration of what high-span young adults show and the opposite of what low-span young adults show. This striking finding in older adults remained significant after controlling for working memory span and for noticing their names in an attended channel. The findings were replicated when presentation rate was slowed and when the ear in which the unattended name was presented was controlled. These results point to an account of older adults' performance involving not only an inhibition factor, which allows high-span young adults to suppress the channel to be ignored, but also an attentional capacity factor, with more unallocated capacity. This capacity allows low-span young adults to notice their names much more often than older adults with comparably low working memory spans do.

The role of reduced working memory storage and processing resources in the associative memory deficit of older adults: simulation studies with younger adults

Previous research indicates that relative to younger adults, older adults show a larger decline in long-term memory (LTM) for associations than for the components that make up these associations. The purpose of the present study was to investigate whether we can impair associative memory performance in young adults by reducing their working memory (WM) resources, hence providing potential clues regarding the underlying causes of the associative memory deficit in older adults. With two experiments, we investigated whether we can reduce younger adults' long-term associative memory using secondary tasks in which either storage or processing WM loads were manipulated, while participants learned name-face pairs and then remembered the names, the faces, and the name-face associations. Results show that reducing either the storage or the processing resources of WM produced performance patterns of an associative long-term memory deficit in young adults. Furthermore, younger adults' associative memory deficit was a function of their performance on a working memory span task. These results indicate that one potential reason older adults have an associative deficit is a reduction in their WM resources but further research is needed to assess the mechanisms involved in age-related associative memory deficits.

Effects of language dominance on item and order memory in free recall, serial recall and order reconstruction

Spanish-English bilinguals (N = 144) performed free recall, serial recall and order reconstruction tasks in both English and Spanish. Long-term memory for both item and order information was worse in the less fluent language (L2) than in the more fluent language (L1). Item scores exhibited a stronger disadvantage for the L2 in serial recall than in free recall. Relative order scores were lower in the L2 for all three tasks, but adjusted scores for free and serial recall were equivalent across languages. Performance of English-speaking monolinguals (N = 72) was comparable to bilingual performance in the L1, except that monolinguals had higher adjusted order scores in free recall. Bilingual performance patterns in the L2 were consistent with the established effects of concurrent task performance on these memory tests, suggesting that the cognitive resources required for processing words in the L2 encroach on resources needed to commit item and order information to memory. These findings are also consistent with a model in which item memory is connected to the language system, order information is processed by separate mechanisms and attention can be allocated differentially to these two systems.

Can the focus of attention accommodate multiple, separate items?

Researchers of working memory currently debate capacity limits of the focus of attention, the proposed mental faculty in which items are most easily accessed. Cowan (1999) suggested that its capacity is about 4 chunks, whereas others have suggested that its capacity is only 1 chunk. Recently, Oberauer and Bialkova (2009) found evidence that 2 items could reside in the focus of attention, but only because they were combined into a single chunk. We modified their experimental procedure, which depends on a pattern of switch costs, to obtain a situation in which chunking was not likely to occur (i.e., each item remained a separate chunk) and still obtained results consistent with a capacity of at least 2 items. Therefore, either the focus of attention can hold multiple chunks or the switch cost logic must be reconsidered.

The status of rapid response learning in aging

Strong evidence exists for an age-related impairment in associative processing under intentional encoding and retrieval conditions, but the status of incidental associative processing has been less clear. In 2 experiments, we examined the effects of age on rapid response learning-the incidentally learned stimulus-response association that results in a reduction in priming when a learned response becomes inappropriate for a new task. Specifically, we tested whether priming was equivalently sensitive in both age groups to reversal of the task-specific decision cue. Experiment 1 showed that cue inversion reduced priming in both age groups with a speeded inside/outside classification task, and in Experiment 2, cue inversion eliminated priming on an associative version of this task. Thus, the ability to encode an association between a stimulus and its initial task-specific response appears to be preserved in aging. These findings provide an important example of a form of associative processing that is unimpaired in older adults.

The cholinergic hypothesis of cognitive aging revisited again: cholinergic functional compensation

It is now possible to reevaluate the cholinergic hypothesis of age-related cognitive dysfunction based on a synthesis of new evidence from cholinergic stimulation studies and cognitive models. We propose that a change of functional circuitry that can be observed through a combination of pharmacologic challenge and functional neuroimaging is associated with age-related changes in cholinergic system functioning. Psychopharmacological manipulations using cholinergic agonists and antagonists have been consistent in replicating patterns of aging seen in functional imaging studies. In addition, studies of anticholinesterase drugs in patients with Alzheimer's disease and mild cognitive impairment show support for the proposal that cholinergic compensation causes alterations in task-related brain activity. Thus, the cholinergic hypothesis of age-related cognitive dysfunction deserves further consideration as new methodologies for evaluating its validity are increasingly being used. Future directions for testing hypotheses generated from this model are presented.

With development, list recall includes more chunks, not just larger ones

The nature of the childhood development of immediate recall has been difficult to determine. There could be a developmental increase in either the number of chunks held in working memory or the use of grouping to make the most of a constant capacity. In 3 experiments with children in the early elementary school years and adults, we show that improvements in the immediate recall of word and picture lists come partly from increases in the number of chunks of items retained in memory. This finding was based on a distinction between access to a studied group of items (i.e., recall of at least 1 item from the group) and completion of the accessed group (i.e., the proportion of the items recalled from the group). Access rates increased with age, even with statistical controls for completion rates, implicating development of capacity in chunks.

Investigating the childhood development of working memory using sentences: new evidence for the growth of chunk capacity

Child development is accompanied by a robust increase in immediate memory. This may be due to either an increase in the number of items (chunks) that can be maintained in working memory or an increase in the size of those chunks. We tested these hypotheses by presenting younger and older children (7 and 12 years of age) and adults with different types of lists of auditory sentences: four short sentences, eight short sentences, four long sentences, and four random word lists, each read with a sentence-like intonation. Young children accessed (recalled words from) fewer clauses than did older children or adults, but no age differences were found in the proportion of words recalled from accessed clauses. We argue that the developmental increase in memory span was due to a growing number of chunks present in working memory with little role of chunk size.

Working memory capacity for spoken sentences decreases with adult ageing: recall of fewer but not smaller chunks in older adults

Previous studies show that older adults have poorer immediate recall for language but the reason is unknown. Older adults may recall fewer chunks from working memory, or may have difficulty binding words together to form multi-unit chunks. We examined these two hypotheses by presenting four types of spoken sentences for immediate free recall, differing in the number and length of chunks per trial: four short, simple sentences; eight such sentences; four compound sentences, each incorporating two meaningful, short sentences; and four random word lists, each under a sentence-like intonation. Older adults recalled words from (accessed) fewer clauses than young adults, but there was no ageing deficit in the degree of completion of clauses that were accessed. An age-related decline in working memory capacity measured in chunks appears to account for deficits in memory for spoken language.

What are the differences between long-term, short-term, and working memory?

In the recent literature there has been considerable confusion about the three types of memory: long-term, short-term, and working memory. This chapter strives to reduce that confusion and makes up-to-date assessments of these types of memory. Long- and short-term memory could differ in two fundamental ways, with only short-term memory demonstrating (1) temporal decay and (2) chunk capacity limits. Both properties of short-term memory are still controversial but the current literature is rather encouraging regarding the existence of both decay and capacity limits. Working memory has been conceived and defined in three different, slightly discrepant ways: as short-term memory applied to cognitive tasks, as a multi-component system that holds and manipulates information in short-term memory, and as the use of attention to manage short-term memory. Regardless of the definition, there are some measures of memory in the short term that seem routine and do not correlate well with cognitive aptitudes and other measures (those usually identified with the term "working memory") that seem more attention demanding and do correlate well with these aptitudes. The evidence is evaluated and placed within a theoretical framework depicted in Fig. 1.

Separating cognitive capacity from knowledge: a new hypothesis

We propose that working memory and reasoning share related capacity limits. These limits are quantified in terms of the number of items that can be kept active in working memory, and the number of interrelationships between elements that can be kept active in reasoning. The latter defines the complexity of reasoning problems and the processing loads they impose. Principled procedures for measuring, controlling or limiting recoding and other strategies for reducing memory and processing loads have opened up new research opportunities, and yielded orderly quantification of capacity limits in both memory and reasoning. We argue that both types of limit might be based on the limited ability to form and preserve bindings between elements in memory.