Age-related differences in working memory and force control under dual-task conditions

The aim of this study was to investigate the relationship between force control and cognitive performance under dual-task conditions in younger (18-22 years) and older adults (65-77 years). Cognitive (n-back test) and motor performance (force-tracking) was measured independently and simultaneously. Results indicated overall age-related differences for the n-back and the force-tracking task. Age-related differences increased during dual-task conditions. While younger adults exhibited no decrease in cognitive or motor performance during dual-task conditions, older adults showed a decrease in motor and cognitive performance. Additionally, when older adults made an error in the cognitive task they tended to show greater variability in the force-tracking task. These results suggest that cognitive motor deficits are responsible for older adults' performance decrements under dual-task conditions.     

Aging ebbs the flow of thought: Adult age differences in mind wandering,executive control,and self-evaluation

Two experiments examined the relations among adult aging, mind wandering, and executive-task performance, following from surprising laboratory findings that older adults report fewer task-unrelated thoughts (TUTs) than do younger adults (e.g., Giambra, 1989, Jackson and Balota, 2012). Because older adults may experience more ability- and performance-related worry during cognitive tasks in the laboratory, and because these evaluative thoughts (known as task-related interference, “TRI”) might be sometimes misclassified by subjects as task-related, we asked subjects to distinguish task-related thoughts from TRI and TUTs when probed during ongoing tasks. In Experiment 1, younger and older adults completed either a go/no-go or a vigilance version of a sustained attention to response task (SART). Older adults reported more TRI and fewer TUTs than did younger adults while also performing more accurately. In Experiment 2, subjects completed either a 1- or a 2-back version of the n-back task. Older adults again reported more TRI and fewer TUTs than younger adults in both versions, while performing better than younger adults in the 1-back and worse in the 2-back. Across experiments, older adults' reduced TUT rates were independent of performance relative to younger adults. And, although older adults consistently reported more TRI and less mind wandering than did younger adults, overall they reported more on-task thoughts. TRI cannot, therefore, account completely for prior reports of decreasing TUTs with aging. We discuss the implications of these results for various theoretical approaches to mind-wandering.     

Aging and path integration skill: kinesthetic and vestibular contributions to wayfinding

In a triangle completion task designed to assess path integration skill, younger and older adults performed similarly after being led, while blindfolded, along the route segments on foot, which provided both kinesthetic and vestibular information about the outbound path. In contrast, older adults' performance was impaired, relative to that of younger adults, after they were conveyed, while blindfolded, along the route segments in a wheelchair, which limited them principally to vestibular information. Correlational evidence suggested that cognitive resources were significant factors in accounting for age-related decline in path integration performance.     

Environmental topography and postural control demands shape aging-associated decrements in spatial navigation performance

This study tests the hypothesis that aging-induced cognitive permeation of sensorimotor functions contributes to adult age differences in spatial navigation performance. Virtual maze-like museums were projected in front of a treadmill. Sixteen 20-30-year-old men and sixteen 60-70-year-old men performed a way-finding task in city-block or variable topographies while walking with or without support. Walking support attenuated age-related decrements in navigational learning. Navigation load increased trunk-angle variability for older adults only. Age differences in spatial knowledge persisted despite perfect place-finding performance. City-block topography was easier than variable topography for younger adults only, indicating age-related differences in reliance on spatial relational learning. Attempts at supporting older adults' navigation performance should consider sensorimotor/cognitive interactions and qualitative differences in navigational activity.     

Relationships between mind-wandering and attentional control abilities in young adults and adolescents

Recent findings suggest that mind-wandering—the occurrence of thoughts that are both stimulus-independent and task-unrelated—corresponds to temporary failures in attentional control processes involved in maintaining constant task-focused attention. Studies supporting this proposal are, however, limited by a possible confound between mind-wandering episodes and other kinds of conscious experiences, such as external distractions (i.e., interoceptive sensations and exteroceptive perceptions). In the present study, we addressed this issue by examining, in adolescents and young adults, the relations between tasks measuring attentional control abilities and a measure of mind-wandering that is distinct from external distractions. We observed (1) that adolescents experienced more frequent external distractions, but not more mind-wandering, than young adults during the Sustained Attention to Response Task (SART) and (2) that, in young adults, the influence of external distractions on SART performance was fully accounted for by attentional control abilities, whereas mind-wandering was associated with decreases in SART performance above and beyond what was explained by attentional control abilities. These results show that mind-wandering cannot be entirely reduced to failures in the ability to maintain one's attention focused on task, and suggest that external distractions rather than mind-wandering are due to attentional control failures.     

Aging, metamemory, and high-confidence errors: a misrecollection account

Two experiments showed that older adults were worse than younger adults at judging the accuracy of their responses on source identification (i.e., who said what) and cued-recall tests. It is important to note that this age-related metamonitoring impairment occurred even after older and younger adults were matched on overall source accuracy and cued-recall accuracy. By contrast, older and younger adults showed comparable metamonitoring capacities when assessing the likely accuracy of old-new recognition judgments and responses to questions about general knowledge. These experiments are consistent with the misrecollection account of cognitive aging, which suggests that age-related memory impairments are due to older adults' vulnerability to making high-confidence errors when answering questions that require memory for specific details about recently learned events.     

Aging, source memory, and misrecollections

The authors propose an illusory recollection account of why cognitive aging is associated with episodic memory deficits. After listening to statements presented by either a female or a male speaker, older adults were prone to misrecollecting past events. The authors' illusory recollection account is instantiated in a new illusory recollection signal detection model that provides a better fit of older adults' data than does the standard signal detection model. They observed that age-related differences in source memory (as measured by source d' scores) virtually disappear after accounting for the occurrence of illusory recollections. These data suggest that age-related source memory impairments are not due to older adults' remembering less diagnostic source information and having to guess more. Instead, older adults appear to misremember past events more often than younger adults.     

Aging and intraindividual variability in performance: analyses of response time distributions

It has been suggested that older adults are more variable in their performance because they are more prone to lapses of either attention or intention. In the present experiment, 9 young and 9 older adults each performed nearly 2000 trials of a same-different judgment task. As expected, older adults were slower and more variable than young adults. When the age-related difference in speed was taken into account, however, the older adults were, if anything, less variable than the young adults. When younger and older adults' RT distributions were analyzed using quantile-quantile plots and by fitting ex-Gaussian and Weibull functions, there was no consistent evidence that older adults' distributions were more skewed than young adults', as would be predicted by age-related increases in lapses of attention or intention. Importantly, there was a positive, linear relation between RT and intraindividual variability, and the same relation was observed both within subjects (practice increased speed and reduced variability) as well as between subjects (regardless of age, slower individuals were more variable). Thus, the present results suggest that there may be a general law governing the relation between average RT and variability, and that the greater performance variability of older adults primarily reflects their greater average RTs.     

Age-related Differences in Working Memory and Force Control under Dual-task Conditions

ABSTRACT

The aim of this study was to investigate the relationship between force control and cognitive performance under dual-task conditions in younger (18–22 years) and older adults (65–77 years). Cognitive (n-back test) and motor performance (force-tracking) was measured independently and simultaneously. Results indicated overall age-related differences for the n-back and the force-tracking task. Age-related differences increased during dual-task conditions. While younger adults exhibited no decrease in cognitive or motor performance during dual-task conditions, older adults showed a decrease in motor and cognitive performance. Additionally, when older adults made an error in the cognitive task they tended to show greater variability in the force-tracking task. These results suggest that cognitive motor deficits are responsible for older adults' performance decrements under dual-task conditions.     

Age-related changes in brain–behaviour relationships: Evidence from event-related functional MRI studies

A fundamental aim of studies in neurocognitive ageing is to understand age-related changes in brain–behaviour relationships. Neuroimaging techniques such as positron emission tomography (PET) and functional magnetic resonance imaging (fMRI) can be used for observation of these age-related changes only if the assumption of age-equivalent relations between neural activity and haemodynamic activity is valid. In one study, we characterised age-related differences in the coupling of the haemodynamic response to neural activity and found greater voxel-wise noise in older than in younger adults, but age-equivalent signal magnitude. These results suggested that alternative techniques may be necessary for analysing age-related differences in neuroimaging data. In a second study, we utilised one alternative method for comparing fMRI activation between younger and older adults performing a working memory (WM) task. Across three experiments, the results suggested that age-related functional changes in fMRI activation can be isolated to dorsolateral prefrontal cortex (PFC) during memory retrieval. These results suggest a plausible model for WM decline with normal ageing. In a third study we propose and test a model of age-related PFC dysfunction that may account for these and other age-related differences in cognitive performance.     

Sensitive performance-based assessment of everyday action in older and younger adults

Everyday function is compromised by mild cognitive changes in aging. These changes predict risk for future decline and dementia but remain poorly characterized, largely due to a scarcity of sensitive, objective measures.Twenty-seven younger adults and 25 non-demented older adults completed the Naturalistic Action Test (NAT), a performance-based measure of everyday action involving simple and complex tasks. Performance was coded for overt errors and subtle inefficiencies. Participants also completed self-report functional measures and cognitive tests. Mixed ANOVAs revealed that older adults made more subtle NAT errors with high task demands; groups did not differ in overt errors. Correlations did not reveal significant relations between self-report and NAT errors, but NAT performance was correlated with learning and recall.The NAT provides a promising tool for detecting subtle age-related changes and examining decline across levels of impairment. Self-report may lack sensitivity to subtle changes, and episodic memory changes underlie early functional disruption.     

Anatomy of an error: A bidirectional state model of task engagement/disengagement and attention-related errors

We present arguments and evidence for a three-state attentional model of task engagement/disengagement. The model postulates three states of mind-wandering: occurrent task inattention, generic task inattention, and response disengagement. We hypothesize that all three states are both causes and consequences of task performance outcomes and apply across a variety of experimental and real-world tasks. We apply this model to the analysis of a widely used GO/NOGO task, the Sustained Attention to Response Task (SART). We identify three performance characteristics of the SART that map onto the three states of the model: RT variability, anticipations, and omissions. Predictions based on the model are tested, and largely corroborated, via regression and lag-sequential analyses of both successful and unsuccessful withholding on NOGO trials as well as self-reported mind-wandering and everyday cognitive errors. The results revealed theoretically consistent temporal associations among the state indicators and between these and SART errors as well as with self-report measures. Lag analysis was consistent with the hypotheses that temporal transitions among states are often extremely abrupt and that the association between mind-wandering and performance is bidirectional. The bidirectional effects suggest that errors constitute important occasions for reactive mind-wandering. The model also enables concrete phenomenological, behavioral, and physiological predictions for future research.     

When the mind wanders: Age-related differences between young and older adults

Interest in mind wandering (MW) has grown in recent years, but few studies have assessed this phenomenon in older adults. The aim of this study was to assess age-related differences between young, young–old and old–old adults in MW using two versions of the sustained attention to response task (SART), one perceptual and one semantic. Different indicators were examined (i.e., reported MW episodes and behavioral indices of MW such as response time latency and variability, incorrect response and omission errors). The relationship between MW, certain basic mechanisms of cognition (working memory, inhibition and processing speed), cognitive failures and intrusive thoughts in everyday life was also explored. Findings in both versions of the SART indicated that older adults reported a lower frequency of MW episodes than young adults, but some of the behavioral indices of MW (response time variability, incorrect response and omission errors) were higher in old–old adults. This seems to suggest that MW becomes less frequent with aging, but more pervasive and detrimental to performance. Our results also indicated that the role of age and cognitive mechanisms in explaining MW depends on the demands of the SART task considered.     

Aging and motivated cognition: the positivity effect in attention and memory

As people get older, they experience fewer negative emotions. Strategic processes in older adults' emotional attention and memory might play a role in this variation with age. Older adults show more emotionally gratifying memory distortion for past choices and autobiographical information than younger adults do. In addition, when shown stimuli that vary in affective valence, positive items account for a larger proportion of older adults' subsequent memories than those of younger adults. This positivity effect in older adults' memories seems to be due to their greater focus on emotion regulation and to be implemented by cognitive control mechanisms that enhance positive and diminish negative information. These findings suggest that both cognitive abilities and motivation contribute to older adults' improved emotion regulation.     

Adult age differences in visual word identification: functional neuroanatomy by positron emission tomography

Adult age differences in the neural systems mediating semantic (context-independent) memory were investigated using positron emission tomography (PET). Younger (20-29 years) and older (62-70 years) participants performed lexical decision (word/nonword discrimination) and nonsemantic (simple visual search) baseline tasks during PET scanning. Within the lexical decision task, display duration and presentation rate were varied across scans. The behavioral data suggested that although an age-related slowing was evident in visual feature and response processing, the retrieval of semantic/lexical information was similar for younger and older adults. For both age groups, lexical-related activation occurred in inferior prefrontal and occipitotemporal regions of the left hemisphere. Differential activation, as a function of age group, was observed in the left occipitotemporal pathway as a result of older adults' maintaining higher levels of neural activity in striate cortex (during visual search) and in inferior temporal cortex (during lexical decision). The prefrontal activation was similar for the two age groups. Thus, although this form of semantic memory retrieval does not undergo significant age-related decline, an age-related change in the associated pattern of neural activation is evident. These findings differ from previous neuroimaging studies of episodic (context-dependent) memory retrieval, which have suggested that age-related compensatory mechanisms are expressed primarily by greater activation of prefrontal regions for older adults than for younger adults.     

Does a time-monitoring deficit influence older adults' delayed retrieval shift during skill acquisition?

The authors evaluated age-related time-monitoring deficits and their contribution to older adults' reluctance to shift to memory retrieval in the noun-pair lookup (NP) task. Older adults (M = 67 years) showed slower rates of response time (RT) improvements than younger adults (M = 19 years), because of a delayed strategy shift. Older adults estimated scanning latencies as being faster than they actually were and showed poor resolution in discriminating short from long RTs early in practice. The difference in estimated RT for retrieval and scanning strategies predicted retrieval use, independent of actual RT differences. Separate scanning and recognition memory tasks revealed larger time-monitoring differences for older adults than in the NP task. Apparently, the context of heterogeneous RTs as a result of strategy use in the NP task improved older adults' accuracy of RT estimates. RT feedback had complex effects on time-monitoring accuracy, although it generally improved absolute and relative accuracy of RT estimates. Feedback caused older adults to shift more rapidly to the retrieval strategy in the NP task. Results suggest that deficient time monitoring plays a role in older adults' delayed retrieval shift, although other factors (e.g., confidence in the retrieval strategy) also play a role.     

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

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

An examination of age-related changes in the control of lexical and sublexical pathways in mapping spelling to sound

The current study investigated the extent to which young and older adults are able to direct attention to distinct processes in mapping spelling onto sound. Young and older adults completed either a speeded pronunciation task (reading aloud words) or regularization task (pronouncing words based on spelling-to-sound correspondences, e.g., pronouncing PINT such that it rhymes with HINT) in order to bias processing of lexical, whole-word information, or sublexical, spelling-to-sound mapping, respectively. Both younger and older adults produced reduced word-frequency effects and lexicality effects in the regularization task compared to the normal pronunciation task. Importantly, compared to younger adults, older adults produced exaggerated effects of task (i.e., pronunciation vs. regularization) on the observed frequency and lexicality effects. These results highlight both the flexibility of the lexical processing system and changes in the influence of the underlying lexical route due to additional 50 years of reading experience and/or changes in attentional control.     

Effects of Age and Control Beliefs on Resource Allocation During Reading Abstract

Past work suggests that a strong sense of control over one's cognitive ability is associated with higher levels of cognitive performance and that control beliefs may be even more important in later life, due to age-related declines in cognitive processes. However, less is known about the effects of control beliefs on encoding strategies, and whether these effects are comparable for younger and older adults. Participants were divided into high- (HC) and low- control (LC) beliefs groups based on their scores on the Personality in Intellectual-Aging Contexts Inventory. Participants then read relatively easy and difficult passages word-by-word on a computer for subsequent recall. The data suggest that among older, but not younger adults, control beliefs are particularly important when reading difficult passages. Findings as they relate to models of self-regulation and to implications for everyday functioning are discussed.