The effects of dual-tasking on arm muscle responses in young and older adults

This study examined whether dual-tasking affects an individual’s ability to generate arm muscle responses following a loss of balance. Nineteen young and 16 older adults recovered their balance in response to a surface translation. This balance task was either completed on its own or while counting backwards by 2’s (easy counting difficulty) or 7’s (hard counting difficulty). With increasing counting difficulty, less attentional resources were assumed to be available for balance recovery. The ability to generate arm muscle responses was quantified through the measurement of electromyographic (EMG) onset latencies and amplitudes from three arm muscles. Results indicated that the attentional requirements of the counting task did not greatly affect EMG onset latencies or amplitudes for both young and older adults. Even when an effect was observed, the magnitude of change was small (e.g., ∼3 ms earlier EMG onset and ∼2.0%MVC smaller EMG amplitude during the dual- compared to the single-task conditions). Thus, the generation of arm muscle responses do not appear to require a significant amount of attentional resources and the decreased ability to cope with cognitive interference with ageing is unlikely to explain why older adults have difficulty in generating arm responses following a loss of balance.     

A longitudinal investigation of perceived control and cognitive performance in young, midlife and older adults

Longitudinal associations between generalized control beliefs (one's perceived capacity to influence events) and cognitive test performance were examined in a population-based sample of young, midlife and older adults. Participants provided measures of perceived control, self-assessed health, education and depression and anxiety symptoms, and completed cognitive tests at two assessments, 4 years apart. For each age group, baseline (between-person) control was positively related to performance on tests of memory (immediate recall and digits backwards), speed (Symbol Digit Modalities Test and choice reaction time) and verbal intelligence (Spot-the-Word). Interaction effects indicated stronger associations of between-person control beliefs with indices of speed for the older age group relative to the younger groups. Within-person changes in control were not significantly associated with changes in cognitive test performance over the study interval. Implications of the findings for self-efficacy based interventions designed to promote cognitive functioning are discussed.     

How scenes containing visual errors affect speech fluency in young and older adults

We compared young and older adults’ speech during an error detection task, with some pictures containing visual errors and anomalies and other pictures error-free. We analyzed three disfluency types: mid-phrase speech fillers (e.g., It’s a little, um, girl), repetitions (e.g., He’s trying to catch the- the birds), and repairs (e.g., She- you can see her legs). Older adults produced more mid-phrase fillers than young adults only when describing pictures containing errors. These often reflect word retrieval problems and represent clear disruptions to fluency, so this interaction indicates that the need to form and maintain representations of novel information can specifically compromise older adults’ speech fluency. Overall, older adults produced more repetitions and repairs than young adults, regardless of picture type, indicating general age-related increases in these disfluencies. The obtained patterns are discussed in the context of the Transmission Deficit Hypothesis and other approaches to age-related changes in speech fluency.     

How young adults address their parents reflects their perception of parenting

A speaker's use of a title for the listener shows the speaker's deference to the listener. Previous studies suggested that the use of kinship terms in the family also shows deference to the listener. The present study focused on young adults' use of kinship terms for their parents to investigate whether their use of kinship terms reflects their perception of their parenting. The participants were 329 Japanese college students, who answered a questionnaire about their forms of address for their parents, perceived parental emotional accessibility, and perceived parental control. They also reported their satisfaction with their parent–child relationships and the frequency of parent–child communication. The results suggest that young adults who use kinship terms for their parents perceive their parents to be more emotionally accessible and communicate with their parents more than those who do not. Young adults who use kinship terms for their father are also more satisfied with their father–child relationships than those who do not. Young adults' use of kinship terms might signal not only their deference to their parents, but also their acceptance of their parent–child relationships.     

Postural muscle responses following changing balance threats in young, stable older, and unstable older adults

The authors determined the postural muscle response to support surface perturbations, in relation to aging and level of stability of 16 young adults and 32 older adults who were classified into stable (SOA) and unstable (UOA) groups on the basis of their functional balance abilities. Forward and backward support surface translations of various amplitudes and velocities were used so that postural responses of the standing adults could be elicited. The thigh and leg postural muscle responses were recorded with surface electromyography (EMG). The older groups had significantly longer onset latency in the anterior postural muscles, smaller integrated EMG in the posterior muscles, and greater extent of integrated EMG attenuation over time. The UOA showed longer onset latency in the gastrocnemius following slow backward perturbation and used a greater percentage of the functional capacity of the gastrocnemius muscle than the SOA did. Those findings indicate that the SOA and UOA had limited ability to adapt to changing balance threats; the UOA were more limited than the SOA. When designing balance training programs, therefore, therapists should consider the adult's level of functional stability.     

Hypermnesia: A further examination of age differences between young and older adults

Previous studies that examined age differences in hypermnesia reported inconsistent results. The present experiment investigated whether the different study materials in these studies were responsible for the inconsistency. In particular, the present experiment examined whether the use of a video, as opposed to words and pictures, would eliminate previously reported age differences in hypermnesia. Fifteen college students and 15 older adults viewed a 3‐minute video clip followed by two free‐recall tests. The results indicated that older adults, as a whole, did not show hypermnesia. However, when older adults were divided into low and high memory groups based on test 1 performance, the high memory group showed hypermnesia whereas the low memory group did not show hypermnesia. The older adults in the low memory group were significantly older than the older adults in the high memory group – indicating that hypermnesia is inversely related to age in older adults. Reminiscence did not show an age‐related difference in either the low or high memory group whereas inter‐test forgetting did show an age difference in the low memory group. As expected, older adults showed greater inter‐test forgetting than young adults in the low memory group. Findings from the present experiment suggest that video produces a pattern of results that is similar to the patterns obtained when words and pictures are used as study material. Thus, it appears that the nature of study material is not the source of inconsistency across the previous studies.     

Sustained-attention capacity in young and older adults

The sustained-attention capacity of young (21-29 years) and older (65-78 years) adults was examined using a high-event rate digit-discrimination vigilance task presented at three levels of stimulus degradation. Increased stimulus degradation led to a reduction in the hit rate and to a greater decline in hit rate over blocks (increased vigilance decrement). Sensitivity (d') declined over blocks only at the highest level of stimulus degradation. Older adults had a lower hit rate and showed greater vigilance decrement than young adults, particularly when stimuli were highly degraded. However, both age groups showed the same pattern of stability in sensitivity when stimulus degradation was moderate, and sensitivity decrement over time when stimulus degradation was high. The results suggest that the process of sustained allocation of capacity--as reflected in temporal changes in sensitivity--operates similarly in young and older adults.     

Semantic satiation in healthy young and older adults

In four experiments, semantic satiation was investigated in young and old adults. In the first two experiments, subjects were repeatedly presented a word (e.g.,dog) and then were presented a pair of words (e.g.,dog-cat ordog-chair) for a relatedness decision. The results of both experiments indicated that for the young adults, the relatedness effect (the difference between response latency on related and unrelated trials) decreased as a function of the number of times the satiated word was repeated, whereas for the older adults, there was no evidence of a decrease in the relatedness effect across repetitions of the satiated word. In the third experiment, we investigated whether phonological codes are also susceptible to satiation. This experiment was similar to the first two experiments with the exception that subjects made rhyme decisions (same-claim vs.same-dime) instead of semantic relatedness decisions. The results of this experiment did not yield any evidence of satiation for either the young adults or the older adults. The final experiment eliminated a simple decrease in attentional alertness or fatigue account of the semantic satiation effects found in the first two experiments. In this experiment, the repeated word was always unrelated to the pair of words presented for the relatedness decision. The results of this experiment did not yield any evidence of semantic satiation for either the young or the older adults. The discussion focuses on the mechanisms underlying semantic satiation and the implications of age-related changes in these mechanisms.     

Self-initiated object-location memory in young and older adults

The present study explored self-initiated object-location memory in ecological contexts, as aspect of memory that is largely absent from the research literature. Young and older adults memorized objects-location associations they selected themselves or object-location associations provided to them, and elaborated on the strategy they used when selecting the locations themselves. Retrieval took place 30 min and 1 month after encoding. The results showed an age-related decline in self-initiated and provided object-location memory. Older adults benefited from self-initiation more than young adults when tested after 30 min, while the benefit was equal when tested after 1 month. Furthermore, elaboration enhanced memory only in older adults, and only after 30 min. Both age groups used deep encoding strategies on the majority of the trials, but their percentage was lower in older adults. Overall, the study demonstrated the processes involved in self-initiated object-location memory, which is an essential part of everyday functioning.     

A perceived control intervention for at-risk older adults

Models of event causation and affective processes were used to design an experimental intervention for older adults. Ss were 2 at-risk populations, recently disabled and recently bereaved, each with matched nonrisk controls. Ss were randomly assigned to a placebo-contact group, a no-contact control group, or a 4-session, 10-week intervention focused on enhancing perceived control. Dependent variables assessed were personal mastery, psychological well-being and distress, positive and negative affect, and measures of daily events and activities. The intervention was nested within a 16-month longitudinal assessment of stress and adaptation processes in a large sample of community residents. The intervention had mixed effects on reports of personal mastery, but it significantly increased engagement in desirable activities and significantly decreased psychological distress and negative affect. Effects tended to be short-lived, however. Effects of the intervention tended to be particularly significant for the disabled group.     

Velocity discrimination: reliability and construct validity in older adults

The aim of this study was to determine whether a test of velocity discrimination is a reliable and valid measure of proprioception in healthy older adults. Results revealed excellent test-retest reliability over a 2-week period. Velocity discrimination also indicated good construct validity with modest correlations with center of pressure sway outcomes in eyes open and closed conditions as well as stair climbing time. Good construct validity was identified by velocity discrimination sensitivity to age with a higher mean value for the older participants than for the younger participants. These findings suggest velocity discrimination is a valid and reliable measure of velocity sense, which may be included with measures of position and movement sense to enhance the proprioceptive testing repertoire among researchers. Implications of these results are discussed in terms of evaluation of proprioceptive training programs aimed to enhance postural control.     

Semantic priming in young and older adults: evidence for age constancy in automatic and attentional processes

Automatic and attentional components of semantic priming and the relation of each to episodic memory were evaluated in young and older adults. Category names served as prime words, and the relatedness of the prime to a subsequent lexical decision target was varied orthogonally with whether the target category was expected or unexpected. At a prime-target stimulus-onset asynchrony (SOA) of 410 ms, target words in the same category had faster lexical decision latencies than did different category targets. This effect was not significant at a 1,550-ms SOA and was attributed to automatic processes. Expected category targets had faster latencies than unexpected category targets at the 410-ms SOA, and the magnitude of the effect increased at the 1,550-ms SOA. This effect was attributed to attentional processes. These patterns of priming were obtained for both age groups, but in a surprise memory test older adults had poorer recall of primes and targets. We discuss the implications of these results for the hypothesis that older adults suffer deficits in selective attention and for the related hypothesis that attentional deficits impair semantic processing, which causes memory decrements in old age.     

Amygdala responses to emotionally valenced stimuli in older and younger adults

Abstract— As they age, adults experience less negative emotion, come to pay less attention to negative than to positive emotional stimuli, and become less likely to remember negative than positive emotional materials. This profile of findings suggests that, with age, the amygdala may show decreased reactivity to negative information while maintaining or increasing its reactivity to positive information. We used event-related functional magnetic resonance imaging to assess whether amygdala activation in response to positive and negative emotional pictures changes with age. Both older and younger adults showed greater activation in the amygdala for emotional than for neutral pictures; however, for older adults, seeing positive pictures led to greater amygdala activation than seeing negative pictures, whereas this was not the case for younger adults.     

Implicit and explicit memory in young and older adults

In three experiments, young and older adults were compared on both implicit and explicit memory tasks. The size of repetition priming effects in word completion and in perceptual identification tasks did not differ reliably across ages. However, age-related decrements in performance were obtained in free recall, cued recall, and recognition. These results, similar to those observed in amnesics, suggest that older adults are impaired on tasks which require conscious recollection but that memory which depends on automatic activation processes in relatively unaffected by age.     

Feature memory and binding in young and older adults

Intact memory for complex events requires not only memory for particular features (e.g., item, location, color, size), but also intact cognitive processes for binding the features together. Binding provides the memorial experience that certain features belong together. The experiments presented here were designed to explicate these as potentially separable sources of age-associated changes in complex memory—namely, to investigate the possibility that age-related changes in memory for complex events arise from deficits in (1) memory for the kinds of information that comprise complex memories, (2) the processes necessary for binding this information into complex memories, or (3) both of these components. Young and older adults were presented with colored items located within an array. Relative to young adults, older adults had a specific and disproportionate deficit in recognition memory for location, but not for item or for color. Also, older adults consistently demonstrated poorer recognition memory for bound information, especially when all features were acquired intentionally. These feature and binding deficits separately contribute to what have been described as older adults’ context and source memory impairments.     

Subjective age and sleep in middle-aged and older adults

Objective: Chronological age is commonly used to explain change in sleep. The present study examines whether subjective age is associated with change in sleep difficulties across middle adulthood and old age.

Design: Participants were drawn from the second (2004–2005) and third (2013–2014) waves of the Midlife in the United States Survey (MIDUS, N = 2350; Mean Age: 55.54 years), the 2008 and 2014 waves of the Health and Retirement Study (HRS, N = 4066; Mean Age: 67.59 years) and the first (2011) and fourth (2014) waves of the National Health and Aging Trends Survey (NHATS, N = 3541; Mean Age: 76.46). In each sample, subjective age, sleep difficulties, depressive symptoms, anxiety and chronic conditions were assessed at baseline. Sleep difficulties was assessed again at follow-up.

Main outcome measures: Sleep difficulties.

Results: An older subjective age at baseline was related to an increase in sleep difficulties over time in the three samples, and was mediated, in part, through more depressive symptoms, anxiety and chronic conditions. Feeling older was associated with an increased likelihood of major sleeping difficulties at follow-up in the three samples.

Conclusion: Subjective age is a salient marker of individuals’ at risk for poor sleep quality, beyond chronological age.     

The perceived credibility of older adults as witnesses and its relation to ageism

In experiment 1, 267 undergraduates read a case summary and witness statement. Sex and age of the witness (49, 69, 79 or 89 years) were varied. Participants rated the witness's perceived convincingness, confidence, quality of observation, accuracy, honesty, competence, memory, suggestibility, and cognitive functioning. As well as an age effect for honesty, age by sex interactions were observed for several characteristics, particularly for comparisons of the 79-year-olds versus the 49-year-olds, and 89-year-olds versus the 49-year-olds. In experiment 2, 94 undergraduates read the same testimony given by a 79-year-old male or female witness, and completed the Fraboni Scale of Ageism and the Aging Semantic Differential. Participants who evidenced stronger aging stereotypes on these measures rated the witness less favorably than did participants who were less prejudiced. This experiment is the first to show a link between perceived credibility of older adults and ageist attitudes. Practical applications regarding how older witnesses are viewed by jurors, and the criminal justice system more generally, are discussed.     

Instantiation of general terms in young and older adults

Instantiation of general terms in discourse requires inference from general world knowledge and use of linguistic context to particularize meaning. According to the semantic deficit hypothesis, older adults should be less likely than young adults to generate or to store such inferences. In Experiments 1 and 2 an indirect measure, relatedness judgment, was used to assess immediate comprehension and memory for inferences. In Experiment 3 a direct measure, cued recall, was used to tap memory for inferences. No age differences in immediate or delayed memory were observed in Experiments 1 or 2. In Experiment 3 older adults recalled fewer sentences, but there was no evidence for a specific decrement in storage of inferential material. Older adults are not impaired in ability to draw inferences based on general world knowledge, nor are they more likely than young adults to encode linguistic information in a general, stereotypic fashion.     

Relational frameworks for recall in young and older adults

Recent research indicates the presence of an age-related visual processing deficit, for which the elderly may attempt to compensate through the use of relational information. This hypothesis was tested, using the category superiority effect as a model system. In studies of young adults, the category superiority effect has been shown to be confined to relatively abstract stimulus materials, such as verbal items, and to be absent for pictures. However, it was predicted that a category superiority effect would be present in elderly adults both for verbal and for pictorial stimuli, since the elderly would be expected to utilize category information to compensate for imagerie deficits. This prediction was confirmed, consistent with the hypothesis advanced above. It was further suggested that the establishment of a prior framework for recall, based on relational information, would reduce this effect significantly. This prediction was also confirmed. This research was supported by Grant AGI 1605, National Institute on Aging, and by a grant from the School of Natural Sciences, California State University, Fresno.