Age differences in the allocation of study time account for age differences in memory performance

How aging affects the utilization of monitoring in the allocation of study time was investigated by having adults learn paired associates during multiple study-test trials. During each trial, a subject paced the presentation of individual items and later judged the likelihood of recalling each item on the upcoming test; after all items had been studied and judged, recall occurred. For both age groups in Study 1, (1) people’s judgments were highly accurate at predicting recall and (2) intraindividual correlations between judgments (or recall) on one trial, and study times on the next trial were negative, which suggests that subjects utilized monitoring to allocate study time. However, the magnitude of these correlations was less for older than for younger adults. Study 2 revealed that these differences were not due to age differences in forgetting. Results from both studies suggest that older adults do not utilize on-line monitoring to allocate study to the same degree as younger adults do, and that these differences in allocation contribute to age deficits in recall.     

Influence of processing speed on adult age differences in working memory.

Two studies are reported in which adults ranging from 18 to 80 years of age performed tasks designed to measure working memory functioning and perceptual comparison speed. The results from both studies indicated that statistical control of the measures of perceptual comparison speed greatly attenuated the age-related variance in measures of working memory even when working memory was assessed under self-paced conditions. Additional results in the second study supported the hypothesis that the speed influence was manifested in the rate of activating information rather than in the rate at which it was lost as a function of time or other processing.     

Selective adult age differences in an age-invariant multifactor model of declarative memory

Confirmatory factor analysis was used to test competing models of declarative memory. Data from middle-aged participants provided support for a model comprised of 2 2nd-order (episodic and semantic memory) and 4 1st-order (recall, recognition, fluency, and knowledge) factors. Extending this model across young-old and old-old participants established support for age invariance. Tests of group differences showed an age deficit in episodic memory that was more pronounced for recall than for recognition. For semantic memory, there was an increase in knowledge from middle to young-old age and thereafter a decrease. Overall, the results support the view that episodic memory is more age sensitive than semantic memory, but they also indicate that aging has differential effects within these 2 forms of memory.     

Recollection and familiarity in recognition memory: adult age differences and neuropsychological test correlates

Dual process theories account for age-related changes in memory by proposing that old age is associated with deficits in recollection together with invariance in familiarity. The authors evaluated this proposal in recognition by examining recollection and familiarity estimates in young and older adults across 3 process estimation methods: inclusion/exclusion, remember/know, and receiver operating characteristics (ROC). Consistent with a previous literature review (Light, Prull, LaVoie, & Healy, 2000), the authors found age invariance in familiarity when process estimates were derived from the inclusion/exclusion method, but the authors found age differences favoring the young when familiarity estimates were derived from the remember/know and ROC methods. Recollection estimates were lower for older adults in all 3 methods. Recollection and familiarity had variable relationships with frontal- and temporal-lobe measures of neuropsychological functioning in older adults, depending on which method was used to generate process estimates. These data suggest that although recollection deficits appear to be the rule in aging, not all estimates of familiarity show age invariance.     

Using a modified lag task to measure adult age differences in working memory

Four groups of adults, ages 40 to 70+ years, took the Modified Lag Task which requires that participants remember lists of words and subsequently recall the first, second, or third word from the end of the list. Previously, the task showed convergent validity with the operation span (a complex span measure) and a divergent validity with the digit span (a simple span measure). To establish predictive validity, the present study was designed to assess if this task could separate four age groups in working memory performance. The present study found support for the validity of the Modified Lag Task; however, additional research is warranted to further develop the construct validity of this task.     

Adult age differences in working memory

Active and passive measures of short-term memory over a large segment of the adult life span were compared. Two hundred twenty-eight volunteers, aged 30 to 99 years, performed the digit span forward and backward task, the Peterson-Peterson task, and a new working memory task in which active manipulation of information is emphasized. Age differences were slight for passive tasks. For the working memory task, significant declines were found between the ages of 60 to 69 and 70+ years. It is suggested that the age differences may be due to a decrease in the flexibility with which processing changes are made.     

Adult age differences in working memory

Two experiments were conducted to determine whether adult age differences in working memory should be attributed to less efficient processing, a smaller working memory storage capacity, or both. In Experiment 1, young, middle-age, and older adults solved three addition problems before giving the answers to any. Older adults added as well as young and middle-age adults but showed a more pronounced serial position curve across the three problem positions. In Experiment 2, young and older adults constructed linear orderings (e.g., ABCD) from pairwise information presented in sentences (e.g., BC). Manipulations involving processing (e.g., type of sentence) did not interact with age differences, but those involving storage capacity (e.g., ordering length) did. All main effects and interactions support the hypothesis of a smaller storage capacity but do not rule out some processing deficit in older adults.     

Adult age differences in short-term memory and subsequent long-term memory for actions.

Short-term memory for actions was investigated for young adult and elderly adult subjects with the Brown-Peterson procedure at retention intervals of 0 and 15 s. The short-term memory trials were followed by the long-term recall of the prior to-be-remembered actions. The 15-s retention interval was filled either with no activity or with 1 of 3 different interfering activities. Verbal interference had little effect on short-term memory at either age level. Actions performed in the interval either by the subjects or by the experimenter produced significantly lower recall scores at each age level, with the decrement being more pronounced for the elderly than for the young subjects. The long-term memory results indicated that successful short-term recall enhanced later long-term recall, regardless of age level.     

Adult age differences in explanations and memory for behavioral information

Age differences in the effects of knowledge-based expectations on both the use of integrative memory processes and recall were examined. In the context of an impression-formation task, young and older adults were presented with lists containing behaviors that varied in consistency with attributed personality traits. Younger adults recalled trait-inconsistent behaviors better than consistent ones, but older adults exhibited no such consistency effect. The age difference in performance was related to the younger adults' spontaneously producing more explanations for inconsistent behaviors. Explanations are assumed to facilitate access to such information by establishing associations with other behavioral information residing in memory. When age differences in the use of explanation-based processing were controlled, the age differences in the effects of consistency on memory were eliminated.     

A diffusion model analysis of adult age differences in episodic and semantic long-term memory retrieval

Two experiments investigated adult age differences in episodic and semantic long-term memory tasks, as a test of the hypothesis of specific age-related decline in context memory. Older adults were slower and exhibited lower episodic accuracy than younger adults. Fits of the diffusion model (R. Ratcliff, 1978) revealed age-related increases in non-decisional reaction time for both episodic and semantic retrieval. In Experiment 2, an age difference in boundary separation also indicated an age-related increase in conservative criterion setting. For episodic old-new recognition (Experiment 1) and source memory (Experiment 2), there was an age-related decrease in the quality of decision-driving information (drift rate). As predicted by the context-memory deficit hypothesis, there was no corresponding age-related decline in semantic drift rate.     

Adult age differences in memory performance: tests of an associative deficit hypothesis

An associative hypothesis to explain and predict older adults' deficient explicit episodic memory performance was outlined and tested. The hypothesis attributes a substantial part of older adults' deficient memory performance to their difficulty in merging unrelated attributes-units of an episode into a cohesive unit. Although each of the components can be memorized to a reasonable degree, the associations that tie the attributes-units to each other grow weaker in old age. Four experiments are reported that provide (a) a converging validity to the hypothesis by demonstrating this associative deficit for both interitem relationships and intraitem relationships and (b) a discriminant validity to the hypothesis by contrasting and testing competing predictions made by the associative hypothesis and by alternative hypotheses. The implications of these results to older adults' episodic memory performance are discussed.     

Processing resources and age differences in working memory

This study investigated the performance of young and old subjects on a modified version of the working memory task developed by Baddeley and Hitch (1974). Subjects were required to verify a set of sentences of varying complexity while they repeated aloud zero, two, or four words. The older subjects took longer to verify the sentences, especially when the sentences were grammatically complex, but the effect of concurrent memory load on verification latency was the same in both groups. These results cast doubt on the notion that there is an age-related decline in one general pool of processing resources. They also suggest that older people have greater difficulty with the active processing aspects, rather than with the passive holding aspects, of working memory tasks.     

Task complexity and age differences in working memory

This study investigated age-related differences in working memory using a modified version of the Daneman and Carpenter (1980) working memory task. The subjects were required to verify a series of sentences, and then at the end of each series recall the final word of each sentence. Each series varied in length from one to five sentences. Performance on this task was compared with performance in a word-alone condition, in which the subject had to remember an equivalent list of single words but without sentence verification. When sentences of positive grammatical form were used in the sentence-span condition, age differences were no greater than in the word alone condition; however, the age decrement increased when sentences of negative grammatical form were used. There were no interactions between age and pacing or between age and the number of sentences in each set. These results are discussed in relation to theories of age differences in working memory.     

Adult age differences in temporal and item memory

Three experiments tested whether the relationship between age differences in temporal and item memory depends on the degree to which the item memory measure relies on memory for context. The authors predicted a stronger relationship of temporal memory to free recall than to recognition memory. Results showed that age differences in temporal memory could be eliminated after controlling for free recall but not recognition memory performance. Under some conditions recognition memory accounted for a significant portion of age-related variance in temporal memory. These results challenge past research that has interpreted age differences in temporal and item memory as independent and suggest that a generalized decline in context memory may underlie reduced performance in older adults on all types of memory tests.     

Explaining age differences in temporal working memory

To determine the cognitive mechanisms underlying age differences in temporal working memory (WM), the authors examined the contributions of item memory, associative memory, simple order memory, and multiple item memory, using parallel versions of the delayed-matching-to-sample task. Older adults performed more poorly than younger adults on tests of temporal memory, but there were no age differences in nonassociative item memory, regardless of the amount of information to be learned. In contrast, a combination of associative and simple order memory, both of which were reduced in older adults, completely accounted for age-related declines in temporal memory. The authors conclude that 2 mechanisms may underlie age differences in temporal WM, namely, a generalized decline in associative ability and a specific difficulty with order information.     

Adult age differences in memory for massed and distributed repeated actions

Adult age differences in memory for actions were investigated in 2 experiments in which actions were repeated with massed or distributed spacing. In Experiment 1, subjects received a mixed series of actions, half performed once, the others twice, with repetitions either massed or distributed. Young subjects recalled more actions than did the elderly, and more distributed actions were recalled than massed actions. However, the Age X Spacing interaction was not significant. A probable inhibitory mechanism with a mixed list was avoided in Experiment 2 by use of unmixed series. Actions were performed once only, twice only in massed repetitions, or twice only in distributed repetitions. The age difference was significant, and more actions were recalled in the distributed condition than in either of the other conditions, the results of which did not differ from one another. The Age X Conditions interaction was negligible. These results imply that elderly subjects are as likely as young subjects to encode contextual information while performing actions.     

The source of adult age differences in event-based prospective memory: a multinomial modeling approach

Event-based prospective memory involves remembering to perform an action in response to a particular future event. Normal younger and older adults performed event-based prospective memory tasks in 2 experiments. The authors applied a formal multinomial processing tree model of prospective memory (Smith & Bayen, 2004) to disentangle age differences in the prospective component (remembering that you have to do something) and the retrospective component (remembering when to perform the action) of prospective memory performance. The modeling results, as well as more traditional analyses, indicate age differences in the resource-demanding prospective component.     

Professional expertise does not eliminate age differences in imagery-based memory performance during adulthood.

Using a testing-the-limits paradigm, the authors investigated the modulation (attenuation) of negative adult age differences in imagery-based memory performance as a function of professional expertise. Six older graphic designers, 6 normal older adults, 6 younger graphic design students, and 6 normal younger students participated in a 19-session program with a cued-recall variant of the Method of Loci. Older graphic designers attained higher levels of mnemonic performance than normal older adults but were not able to reach younger adults' level of performance; a perfect separation of age groups was achieved. Spatial visualization was a good predictor of mnemonic performance. Results suggest that negative adult age differences in imagery-based memory are attenuated but not eliminated by the advantages associated with criterion-relevant ability (talent) and experience.     

Decomposing adult age differences in symbol arithmetic

A componential analysis was conducted to determine the locus of adult age differences in symbol arithmetic. Measures of the duration of two proposed components, substitution of digits for symbols and the addition or subtraction of the digits resulting from these substitutions, were obtained from 52 young adults and 52 older adults. Tests of working memory, perceptual speed, motor speed, and associative learning were also administered to all subjects. The results were most consistent with an interpretation postulating that the speed of many different cognitive processes decreases with increased age. Considerable age-related variance remained in the measures of symbol arithmetic performance after statistical control of working memory and associative learning performance, casting doubt on alternative hypotheses of the source of age-related differences in this task.     

Working-memory mediationof adult age differences in integrativereasoning

Three research methods were used to investigate the hypothesized mediational influence of working memory on age-related differences in integrative reasoning. Results from all three procedures were consistent with the hypothesis because (1) statistical control of an index of working memory attenuated the age differences in reasoning accuracy, (2) young adults were more accurate than older adults in a measure reflecting the preservation of information during processing, and (3) young adults performing the task with a concurrent memory load exhibited a qualitative pattern of performance similar to that of older adults performing the task without a concurrent memory load.