Advancing age progressively affects obstacle avoidance skills in the elderly

The ability to adequately avoid obstacles while walking is an important skill that allows safe locomotion over uneven terrain. The high proportion of falls in the elderly that is associated to tripping over obstacles potentially illustrates an age-related deterioration of this locomotor skill. Some studies have compared young and old adults, but very little is known about the changes occurring within different age groups of elderly. In the present study, obstacle avoidance performance was studied in 25 young (20-37 years) and 99 older adults (65-88 years). The participants walked on a treadmill at a speed of 3 km/h. An obstacle was dropped 30 times in front of the left foot at various phases in the step cycle. Success rates (successful avoidance) were calculated and related to the time available between obstacle appearance and the estimated instant of foot contact with the obstacle (available response times or ARTs ranging from 200 to more than 350 ms). In addition, latencies of avoidance reactions, the choice of avoidance strategies (long or short step strategy, LSS or SSS), and three spatial parameters related to obstacle avoidance (toe distance, foot clearance, and heel distance) were determined for each participant. Compared to the young, the older adults had lower success rates, especially at short ARTs. Furthermore, they had longer reaction times, more LSS reactions, smaller toe and heel distances, and larger foot clearances. Within the group of elderly, only the 65-69 year olds were not different from young adults with respect to success rate, despite marked changes in the other parameters measured. In particular, even this younger group of elderly showed a dramatic reduction in the amount of SSS trials compared to young adults. Overall, age was a significant predictor of success rates, reaction times, and toe distances. These parameters deteriorated with advancing age. Finally, avoidance success rates at short ARTs were considerably worse in elderly participants who sustained recurrent falls in the six-month period prior to the assessment compared to those who sustained no or only one fall. An exercise program has been shown to improve avoidance success rates, especially at short ARTs, but the training effects on the determinants of success still need to be assessed.     

Skill learning in the elderly: diminished implicit and explicit memory for a motor sequence.

Explicit and implicit memory for a cognitive-motor sequence was studied in elderly and young adults. Implicit memory was examined in a serial reaction-time paradigm in which sequences of hand postures repeated cyclically, then shifted to random sequences. Two control groups received random sequences throughout. Movement times (MTs) across the first 4 blocks did not improve more in the elderly-repeated than in the elderly-random group. In contrast, the young-repeated group showed greater improvement in MT across these blocks than the young-random group. MT was less affected in the elderly than in the young by shifts between repeated and random sequences, indicating impaired implicit memory. Explicit memory, which was assessed by free recall and cued recall, also was impaired in the elderly. Diminished implicit memory in the elderly could not be explained solely by the possible intrusion of conscious recollection strategies.     

Aging and repetition priming for targets and distracters in a working memory task

A combined working memory/repetition priming task was administered to 13 young (mean age 23) and 13 elderly (mean age 69) adults. Each participant memorized a sample target face at the beginning of a trial and then determined whether each of 13 serially presented test faces matched the sample target. In each trial, both the target and one particular distracter face were repeated during the test phase. Within-trial repetition priming effects indicated the contribution of implicit memory to task performance. Response times decreased as items were tested repeatedly within a trial, but this decrement was greater for distracters than for targets. Young and older participants were equally accurate at identifying targets, but elderly were slightly less accurate for distracters. Elderly participants showed repetition priming effects for both targets and distracters, while the young showed such effects only for distracters. The results suggest that active maintenance in working memory, but not inhibition or rejection of distracters, may suppress implicit memory systems.     

Episodic memory in dementia of the alzheimer type and in normal ageing: Similar impairment in automatic processing

A perceptual identification task was used to provide an implicit measure for automatic memory processes. The facilitation of word identification on repeated presentation is taken as a measure of the automatic retrieval of an episode. In addition, recognition memory was tested. The recognition task is an explicit test of memory and relies mainly on controlled processing. In the first experiment 11 patients suffering from probable Alzheimer disease and 11 normal age- and sex-matched controls were tested. Both groups exhibited a rather small facilitation effect (ca 7%) but did not differ in the size of the effect. However, when tested explicitly, a difference in recognition memory existed between the two groups. In the second experiment the performance of 11 normal young subjects was compared to that of 11 normal elderly subjects. Whereas the elderly group showed a small facilitation effect similar to that observed in the first experiment, a considerable facilitation effect was found for the young group. Also, the elderly group had poorer recognition memory than the young group.     

Effects of distinctive context on memory for objects and their locations in young and elderly adults

Sharps and Gollin (1987, 1988) reported that older adults' memory for both objects and their spatial location is more facilitated than that of young adults when items are studied in a distinctive visual context. They also reported that age differences in spatial memory and item memory can be ameliorated if the items are studied in a distinctive context. The goal of this study was to verify and extend these findings by examining memory for everyday objects when the objects were studied on a (a) plain surface, (b) black-and-white schematic map, or (c) colored model. In Experiment 1, item memory was examined, and in Experiment 2, spatial memory was studied. The results indicated that spatial memory improved with the addition of distinctive context but item memory did not. Moreover, there was no evidence that elderly adults were more facilitated by the distinctive context than were the young.     

Self-Reference enhances memory for multi-element events judged likely to happen in young and older adults

ABSTRACT

We investigated whether the strategy of self-reference can benefit memory for multi-element events, a kind of relational memory that is relatively less studied but highly relevant to daily life. Young and older adults imagined different person-object-location events with reference to themselves and two famous others (i.e., George Clooney and Oprah Winfrey), rated the likelihood that each event would happen, and then completed incidental memory tests on different pairs of elements within the event. We found that self-reference enhanced memory for object-location and person-object pairs in both age groups. Such self-reference effects were observed consistently only for events rated as likely to happen. There was also an overall memory advantage for the higher-likelihood events, which did not differ between young and older adults. Further, the self-reference effects were not correlated with memory functioning in either age group. Retrieval of within-event associations showed a significant level of dependency, which did not differ as a function of reference condition or likelihood category. These findings highlight the ways in which self-reference and prior knowledge improve relational memory, and suggest that the advantage of self-reference is not attributable to increased dependence of elements within complex events.     

Temporal memory over the adult lifespan

Performances of noncollege student young adults, middle-aged adults, and elderly adults were contrasted on word temporal memory and paired-associate learning tasks. A comparison group of college-student subjects was also evaluated on each task. Significant effects for age variation were found for each task. The age sensitivity for temporal memory conflicts with one of the criteria commonly established for determining the automaticity of a memory task. In addition, moderately high positive correlations were found for each age group between word temporal memory scores and paired-associate learning scores, implying the involvement of effortful processes over the adult lifespan in word temporal memory.     

Aging and Repetition Priming for Targets and Distracters in a Working Memory Task

ABSTRACT

A combined working memory/repetition priming task was administered to 13 young (mean age 23) and 13 elderly (mean age 69) adults. Each participant memorized a sample target face at the beginning of a trial and then determined whether each of 13 serially presented test faces matched the sample target. In each trial, both the target and one particular distracter face were repeated during the test phase. Within-trial repetition priming effects indicated the contribution of implicit memory to task performance. Response times decreased as items were tested repeatedly within a trial, but this decrement was greater for distracters than for targets. Young and older participants were equally accurate at identifying targets, but elderly were slightly less accurate for distracters. Elderly participants showed repetition priming effects for both targets and distracters, while the young showed such effects only for distracters. The results suggest that active maintenance in working memory, but not inhibition or rejection of distracters, may suppress implicit memory systems.     

A componential analysis of an early learning deficit in mathematics

This study was designed to assess strategy choice and information-processing differences in normal and mathematically disabled first and second grade children. Twenty-three normal and 29 learning disabled (LD) children solved 40 computer-presented simple addition problems. Strategies, and their associated solution times, used in problem solving were recorded on a trial-by-trial basis and each was classified in accordance with the distributions of associations model of strategy choices. Based on performance in a remedial education course, as indexed by achievement test scores, the LD sample was reclassified into a LD-improved group and an LD-no-change group. No substantive differences comparing the normal and LD-improved groups occurred in the distribution of strategy choices, strategy characteristics (e.g., error rates), or rate of information processing. The performance characteristics of the LD-no-change group, as compared to the two remaining groups, included frequent counting and memory retrieval errors, frequent use of an immature computational strategy, poor strategy choices, and a variable rate of information processing. These performance characteristics were discussed in terms of the strategy choice model and in terms of potential long-term memory and working memory capacity deficits. In addition, implications for remedial education in mathematics were discussed.     

Young and older adults' strategies in complex arithmetic

Young and older adults solved complex addition problems such as 49 + 56. Verbal protocols, solution times, and percentage errors documented strategy repertoire and strategy selection in young and older participants and age-related differences in complex arithmetic performance. Both young and older adults used a set of 9 strategies to solve complex addition problems, although many older adults used a smaller strategy repertoire. The data also showed age-related differences in strategy execution and strategy selection. We discuss general implications of the present data to further our understanding of complex arithmetic and the role of strategic variations during aging.     

Degree of cognitive impairment and the dissociation of implicit and explicit memory

One group of normal elderly adults and two groups of cognitively impaired elderly adults were compared on an implicit and an explicit memory task. Degree of impairment affected explicit memory; the mildly and moderately impaired elderly adults demonstrated significantly reduced recognition performance. Degree of impairment also affected implicit memory priming performance, particularly for low frequency items, as measured by a word completion task. Explicit memory performance declined for both cognitively impaired groups, but implicit memory performance was sensitive to the degree or severity of impairment, causing a decline in performance only in the moderately impaired group.     

发散性思维的年龄差异及“位置法”记忆训练的作用

该研究的目的是探讨发散性思维的年龄差异以及“位置法”记忆训练对发散性思维的迁移作用。训练组为经过记忆训练的青年人24名,老年组20名,对照组为相匹配的青年人24名、老年人19名。结果表明:(1)在图形、符号、语义三方面的流畅性、变通性和独特性上,老年组均很显著地比青年组差。青年组的个别差异较大,老年组的更大,尤其是独特性。(2)青年训练组的图形流畅性、独特性及语义的独特性成绩显著优于其对照组,老年训练组图形的变通性有优于其对照组的趋势(P=.052),说明“位置法”记忆训练对发散性思维有一定的间接迁移作用,尤其是对青年人。(3)发散性思维与想象力、数字符号、训练前和训练后词的记忆以及图形的记忆成绩均有很显著正相关。而词汇成绩只与训练组两项发散性思维有显著相关。     

What factors influence prospective memory for elderly people in a naturalistic setting?1

Previous studies comparing prospective memory between the elderly and young adults have shown that elderly adults perform better in naturalistic settings, while young adults perform better in laboratory settings. The purpose of this study was to examine what factors influence prospective memory in naturalistic settings, and we specifically focused on age, the complexity of the prospective memory task, self‐evaluation and knowledge of memory function, retrospective memory, external memory aids, and internal memory strategies as potential influential factors. Eighty‐six healthy, elderly participants were enrolled (44 women and 42 men, mean age = 68.56 years, SD = 4.53). The results showed that the use of external memory aids increased in complex prospective memory tasks that depended on output monitoring, while other factors did not influence prospective memory performance. These results suggest that elderly adults can perform tasks adequately by using external memory aids that compensate for age‐related memory declines in naturalistic settings.     

Age differences in implicit memory: More apparent than real

Elderly subjects and a group of young subjects identified fragmented picture sequences under conditions of focused attention. Two other groups of young subjects carried out this task under divided-attention conditions. Implicit memory, as measured by item-specific savings, was found in all groups, but this effect was smaller in the elderly group. The young subjects, but not elderly subjects, performed better on new items. The divided-attention conditions equated recall and recognition by the young and the elderly, but only the young subjects showed greater savings for recalled items. The elderly subjects’ reduced implicit memory therefore stemmed from their inability to facilitate implicit memory with explicit memory. A second experiment, involving only young subjects tested after delay, produced findings similar to those for the young divided-attention subjects. Implicit memory, as measured by savings in picture completion, does not show an age-related change when the role of explicit memory is considered. Age does, however, reduce skill learning.     

记忆训练对改善少年、青年和老年人认知功能的作用

本工作采用“位置法”(method of loci)对24例少年、24例青年和22例老年被试进行了记忆训练研究。以毕生发展的观点比较认知训练对改善不同年龄人记忆的作用,进而探讨发展的认知功能储备能量的年龄差异和训练的迁移效应。结果表明认知干预措施可在一定程度上改善老年人的记忆,同时也显示了在发展的储能和对图形的迁移效应方面,老年人明显不如青、少年,而青年与少年则彼此相近。     

Familiarity and recognition of faces in old age

Elderly persons exceed young adults in false recognitions of new faces. One account claims there are age-related deficits in memory for context of encounter with faces. Because of these deficits, elderly persons frequently recognize faces on the basis of perceived familiarity (i.e., resemblance to face representations in memory), which is high for some new faces. To test this context-recollection hypothesis, we had young adult and elderly subjects judge whether faces: (1) had been seen previously in a test (though no face was repeated), and (2) were subjectively familiar (though no face was famous). The elderly exceeded the young subjects in seen-before judgements (false recognitions), and only the elderly showed a positive correlation between false recognitions and subjective familiarity. In Experiment 2, this finding was extended from false recognitions to correct recognitions, supporting the view that elderly persons, compared to young adults, rely more on resemblance in recognizing faces.     

Direct and indirect measures of frequency monitoring in young and elderly adults

Memory for frequency of occurrence of novel material (Turkish words) was investigated in young and elderly adults via direct (absolute and relative frequency judgments) and indirect (reading speed) measures. Both young and elderly adults showed increased reading speed as a function of frequency of occurrence (Experiment 1). However, when asked explicitly to identify how often a word occurred (Experiment 1) or which word occurred more often (Experiment 2), elderly subjects were less accurate than young adults. These results support and extend research on age-related dissociations in memory.     

Effect of distinctive encoding on false recognition,discrimination, and decision criteria in young and elderly adults

In order to examine the effects of distinctive encoding on age-related differences in false memory and decision criteria, we used a standard recognition paradigm and manipulated three encoding conditions: control, general, and distinctive. The results revealed main effects of age and encoding condition on hits and false recognition, and interactions between these variables, with elderly adults benefiting more than young adults from the encoding tasks. In the distinctive encoding condition, the age-related difference on false recognition was eliminated. These findings are discussed in terms of an age-related deficit in self-initiated distinctive processing. Further analyses showed that elderly adults used a more lenient decision criterion than young adults. Distinctive encoding led all subjects to use stringent decision criteria, but did not eliminate age differences.     

Sequential difficulty effects during execution of memory strategies in young and older adults

This study aimed at uncovering factors influencing execution of memory strategies and at furthering our understanding of ageing effects on memory performance. To achieve this end, we investigated strategy sequential difficulty (SSD) effects recently demonstrated by Uittenhove and Lemaire in the domain of problem solving. We found that both young and older participants correctly recalled more words using a sentence-construction strategy when this strategy followed an easier strategy (i.e., repetition strategy) or a harder strategy (i.e., mental-image strategy). These SSD effects were of equal magnitude in young and older adults, correlated significantly with Stroop performance in both young and older adults and correlated with N-back performance only in young adults. These findings have important implications for furthering our understanding of memory strategy execution and age-related variations in memory performance, as well for understanding mechanisms underlying SSD effects.     

Emergence of Information-Retrieval Strategies in Numerical Cognition: A Developmental Study

A series of simple addition problems was presented in a reaction time, true-false verification task to subjects in Grades 2 through 4 and in college. This information-processing paradigm was used to measure the solution strategies used for problems that sometimes are solved too rapidly and accurately to allow for meaningful error analysis. A series of structural models representing different processing sequences was tested against reaction times for solution to different two-term addition problems. Young children and adults alike used a memory access process to solve highly overlearned addition problems such as 1 + 1 = 2, but solution strategies of more difficult problems differed by age. Younger children adopted a slow, effortful, implicit counting strategy, with efficiency developing in the middle elementary school years; adults performed in a manner consistent with at least some models of memory retrieval found in the literature. Children were classified into two groups, independently of grade, based on slope values from a regression equation computed on individual subject data. The two groups comprised what appeared to be "fast" and "slow" processors, who differed in terms of speed of processing as well as strategy used. Our findings are discussed in terms of models of semantic memory and the development of automatic information-processing skills.