Memory for self-generated stimuli in young and old adults

Theories of the generation effect and the impact of generation constraint: A meta-analytic review

The generation effect is the memory benefit for self-generated compared with read or experimenter-provided information. In recent decades, numerous theories have been proposed to explain the memory mechanism(s) and boundary conditions of the generation effect. In this meta-analysis and theoretical review, we analyzed 126 articles (310 experiments, 1,653 estimates) to assess 7 prominent theories to determine which theories are supported by the existing literature. Because some theories focus on item memory (memory for the generated target) and others focus on context memory (memory for details associated with the generated target), we examined memory effects for both types of details (item, context) in this meta-analysis. Further, we assessed the influence of generation constraint (how constrained participants are to generate a certain response), which recent work has shown affects the magnitude of the generation effect. Overall, the results of this meta-analysis support some theoretical accounts, but not others, as explanatory mechanisms of the generation effect. Results further showed that generation constraint significantly moderates the magnitude of the generation effect, suggesting that this factor should be rigorously investigated in future work. Overall, this meta-analysis provides a review and examination of generation effect theories, and reveals important areas of future research.

Optimizing memory strategy use in young and older adults: The role of metamemory and internal strategy use

We explored whether experiencing differential efficacy of reading and generation for memory in an initial learning trial led younger and older adults to improve recall of read items in a subsequent learning trial, leading to a reduction of the generation effect. In the first trial, generation improved the memory performance of both young and older adults. However, in Trial 2, the generation effect remained significant for older adults only, confirming that they did not change the way they processed read items, unlike the young adults. The older adults were also less spontaneously aware that generation led to better memory performance in the first trial, and, in contrast to the young adults, awareness did not result in a reduction of the generation effect. Moreover, the age-related differences in generation effect reduction were mediated by an independent measure of self-reported internal strategy use. However, when an appropriate environmental support was provided between both trials, older adults improved read items recall at the second trial as well as younger ones, leading to an elimination of the generation advantage for both groups. Environmental support reduced the implication of internal strategy use in the generation effect reduction, suggesting that age-related differences in the implementation of effective encoding processes in Trial 2 would be the consequence of a metamemory deficit, and reduced capacity to self-initiate internal strategies.

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.

The generation effect: a meta-analytic review

The generation effect refers to the finding that subjects who generate information (e.g., produce synonyms) remember the information better than they do material that they simply read. Meta-analytic techniques were used to summarize 445 effect sizes over 86 studies, thereby assessing the magnitude and 11 potential moderators of the generation effect. The size of the generation effect across the 86 studies was .40--a benefit of almost half a standard deviation of generation over reading. The variability of the effect size due to moderator type was substantial, and we attempted to use this information to clarify several theories that have been proposed to explain the generation effect.

Cognitive operations in the generation effect on a recall test: role of aging and divided attention

Generation effect (generated words are better memorized than read words) of anagrams, rhymes, and associates of target words was examined in young, elderly, and very old subjects. Experiments 1 and 2 showed that only young subjects benefit from the generation effect in a free-recall test when the rule is of a phonological nature. Experiments 3, 4, and 5 showed that the generation effect of rhymes was due to a resources-dependent self-initiated process. Experiments 4 and 5 showed that in a divided-attention situation, generation effect of rhymes is not significant in young subjects, but that the generation effect of semantic associates remains significant for both groups (Experiment 5). The results are discussed within the environmental support framework and the transfer-appropriate processing framework.

Age-dependent recall bias for material of internal versus external origin

OBJECTIVE

To learn whether young and aged subjects exhibit different recall biases for internally derived (Internal) versus externally supplied (External) material.

BACKGROUND

Internally derived knowledge, prized by educators and therapists, can bring about dramatic behavioral change. Such information, seldom assessed on formal memory testing, may be preferentially recalled compared with external-origin material. Under some circumstances, however, subjects may demonstrate a recall advantage for externally supplied over internally generated material.

METHOD

We compared Internal and External word recall in young and aged subjects with and without explicit intent to remember.

RESULTS

Although overall the young and aged subjects recalled the same number of words, we did find a word-origin recall bias. This recall bias differed by age group (P = 0.005). When not instructed to remember words, the young subjects tended to remember more External words, while aged subjects remembered more Internal words.

CONCLUSIONS

The differences in the brain mechanisms mediating Internal versus External recall bias are unknown. However, aging may modify an Internal-External memory bias.

Age effect in recall performance according to the levels of processing, elaboration, and retrieval cues

The present study was conducted to investigate the incidence of several factors contributing to age-related memory decrement. Variables manipulated include quality (level of processing encoding conditions), the degree of effort and encoding quantitative elaboration (active/passive encoding conditions), and the influence of retrieval support (free-/cued recall conditions). In support of the environmental support hypothesis, middle-old and old subjects benefited more than young ones from cued recall in all the memory tests. Moreover, the results showed a differential (qualitative vs. quantitative) impairment of conceptual processing between the middle-old and the old-age groups. In the middle-olds, age differences were abolished by deep processing in old adults, age differences were attentuated only with deep and active processing associated with retrieval support. These gradual memory impairments are evaluated according to Mandler's model of memory (1979, In L. G. Nilsson [Ed.], Perspective in memory research. Hillsdale: Lawrence-Erlbaum), and the environmental support hypothesis is discussed in terms of the involvement of encoding and retrieval operations required by the memory task.

Generation effect and frequency judgment in young and elderly adults

In Experiment 1, young and old adults both generated and read the same words either two, five, or eight times (with frequencies combined orthogonally) and then judged the frequency of either the generated or read words. In Experiment 2, young and old adults generated and read different words either one, two, or three times and judged the frequency of both the generated and read words. In both experiments, generation, compared to reading, increased the slope of frequency judgments comparably for the two age groups. In Experiment 1, neither age group could discriminate read from generated frequency. In Experiment 2, a 24-h retention interval reduced the slope of frequency judgments, but did not interact with either age or generation efforts. These results seem most consistent with a semantic activation explanation of the generation effect and a familiarity-based judgment about frequency of occurrence.

Memory for internally generated words in Alzheimer-type dementia: breakdown in encoding and semantic memory

The "generation effect" is a phenomenon in which words that are generated by the subject are remembered better than words which are read. The present experiments examined this effect in patients with mild-to-moderate dementia of the Alzheimer type (DAT), healthy elderly adults, and young adults under a variety of different encoding and retrieval conditions. Experiment 1 employed an intentional learning task with multiple study/test trials using the same list of words. While both the young and elderly adults exhibited higher recall for internally generated words than read words, the DAT patients failed to demonstrate the effect even after repeated exposures to the same stimulus list. Experiment 2 replicated this same pattern of results using an incidental learning paradigm with both recall and recognition tests. Various explanations as to why the DAT patients failed to show the generation effect were discussed with particular emphasis placed on the role of semantic memory and encoding failure.

Age and diabetes related changes in verbal fluency

Non-insulin-dependent diabetes mellitus is present in 7-10% of the aged. This disease appears to be associated with an acceleration of the aging process and results in compromised performance on learning and memory tasks. The present study used a verbal fluency test to examine semantic memory performance in two age groups (55-64 and 65-74 years) of diabetic subjects and controls. In addition, immediate and secondary memory were also examined using the digit symbol and digit span tests and a serial learning task. Results showed that digit symbol performance was poorer for older subjects and diabetics while serial learning was poorer only for diabetic subjects. However, the number of words generated on the verbal fluency test was similar for all groups. Qualitative analyses of the verbal output revealed that older subjects and diabetics produced the greatest number of previously recited words (repetitions). Repetitions may signal a failure to adequately monitor behavior which in turn could contribute to cognitive decline.