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Commentary: Is Memory Something We Have or Something We Do?
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Commentary: Is Memory Something We Have or Something We Do? Elizabeth A. L. Stine University of New Hampshire, U S A As Cohen accurately observes, the focus in much of the published research on memory and aging has been to characterize the conditions which engender age deficits in performance. An assumption underlying much of this literature is that memory is an endogenous trait, something one has, much like hair color or income or a car with an engine of a certain horsepower or a house of a particular size, and that the predominant task of cognitive aging has been to describe ’how much memory’ one has left in late adulthood. In the next few pages, I will use Cohen’s excellent chapter as a starting point from which to argue that memory is not only something we have, but that it is also something we do. While we may possess a home of a certain size and style, the point of having a home is to live in it; we arrange fuiniture and shelving and pictures and flower gardens so that it accommodates our lifestyle. Similarly, at any point in the life-span, our memory systems have certain limits (at a younger age these tend to be limits of knowledge base, while at an older age these tend to be limits of processing capacity), but somehow we manage to live within these limits so as to function in everyday life. While focusing on localization of deficits, memory and aging research has substantially neglected what it is that one must do in order to effectively use one’s memory capabilities into later adulthood. Thus, even though it is clear that there is substantial heterogeneity in the elderly population (Nelson & Dannefer, 1992), and that for some, aging is indeed ’successful’ (Baltes & Baltes, 1990; Rowe & Kahn, 1987), it is not at all clear how this is accomplished in the cognitive domain.
Methodological diversity Cohen aptly notes the wide variety of methods used in the study of memory and aging, categorizing them into phenomenological, psychometric, and experimental approaches. Such diversity will certainly prove to be an asset in untangling the phenomenon of successful cognitive aging. Cronbach (1957) noted some time ago that experimental psychology, which relies on tight control
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of situational variables, and correlational psychology, whose "mission is to observe and organize the data from Nature's experiments" (p. 672), seemed to represent two distinct disciplines within psychology ("The personality, social, and child psychologists went one way; the perception and learning psychologists went the other; and the country between turned into desert" (p. 675)). As he wrote this, he noted some tenuous lines of rapprochement, but called for a "true federation" (p. 675) that would acknowledge that "organism and treatment are an inseparable pair" (p. 683). The field of cognitive aging may well represent the psychology of Cronbach's dreams: growing from the experimentally-driven information processing tradition and the correlationally-driven tradition of developmental psychology, it must necessarily inhabit what used to be that desert in between. Perhaps one of the simplest ways in which this divide has been bridged is through the application of a psychometric (individual differences) approach to cognitive constructs. This has been a notable turn within the field of cognitive psychology whose overriding mission had been to describe general principles for the structure and process underlying mental phenomena. For example, Hunt's work demonstrating processing differences between high- and low-verbal adults (Hunt, Lunneborg, & Lewis, 1975) and Daneman and Carpenter's development of the 'listening span' task as a measure of the efficiency of working memory processing (Daneman & Carpenter, 1980) were critical in leading the field away from almost exclusive focus on the 'generic cognitive processor.' That is, it is not simply the case that short-term memory has a limited capacity of '7+2.' Rather, the more general principle is that processing capacity is limited, and that the value of this limit is variable in the population -- and that this limit has implications for the effectiveness of more general cognitive functioning (Daneman & Carpenter, 1983; Daneman & Tardif, 1987; Hunt et al., 1975; Otero & Kintsch, 1992). In cognitive aging research, this blend of experimental and psychometric approaches is apparent in research which compares age effects among subgroups varying in the efficiency of working memory processing. For example, age differences in memory for language have been found to be reduced or negligible among those who are similar in working memory performance (Stine & Hindman, in press; Tun, Wingfield, & Stine, 1991). Similarly, Salthouse and colleagues (e.g., Salthouse & Babcock, 1991) have shown that measures of simple processing speed can account for a substantial
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portion of age variance in working memory processing, which in turn may mediate age deficits in language memory performance for single sentences (Stine & Wingfield, 1987), for television news (Stine, Wingfield, & Myers, 1990), and for extended radio narratives (Stine, Lachman, & Wingfield, in press). Thus, while the ecological validity of some psychometric tests may be low (as Cohen notes), theory-driven process measures may, in fact, be very useful in accounting for age deficits in memory for language under more naturalistic conditions. Finally, with respect to methodological issues, I wish to affirm Cohen's inclusion of phenomenological approaches, though I would depart somewhat from her position that these methods are necessarily limited or nonanalytic. While it is, of course, true that subjective beliefs of one's ability or memory performance may have little contact with reality, there has been a growing literature in the last few years exploring the relationship between the phenomenological experience of memory and memory performance. For example, in their review of the literature, Cavanaugh and Greene (1990) note that self-confidence in one's ability (self-efficacy) is predictive of perseverance in the face of challenges, the efficiency of analytic thinking in complex cognitive tasks, the tendency to visualize and rehearse strategies for successful performance, and the tempering of perceived stress in a challenging situation. To be sure, (as Cohen points out) our perceptions of memory ability may be optimistic, but Cavanaugh and Greene argue that such a rosy perception of cognitive ability is adaptive. In fact, beliefs about one's memory are often predictive of actual memory performance (e.g., Cavanaugh & Poon, 1989). In a similar vein, Lachman (1983) has shown that believing one's cognitive performance is controlled by internal factors is positively related to memory performance while believing that one's performance is affected by external factors is negatively related to performance. When a measure of working memory span is partialled from the correlation between perceived control and memory, this correlation is negligible (Stine et al., in press), suggesting that control beliefs may affect memory performance by modulating working memory processing. Thus, it is probably the case that phenomenology affects process. This methodological interplay is important since it carries phenomenological methods from the realm of the "merely descriptive" into a position of being an analytic tool. One might envision the strongest strides in
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memory and aging research being made by creative blends of experimental, psychometric, and phenomenological methods.
A word about deficits All three methodological approaches have been used to isolate age-related capacity limits, which must be accommodated in order to age successfully. For some time now, the field of cognitive aging has been driven by the search for an adequate metaphor to capture the empirical findings of loss, with the primary candidates revolving around some loss of capacity. Thus, the causal locus of age deficits in memory has been alternatively postulated to reside in a relative decline in effortful processing (Hasher & Zacks, 1979), a dearth of attentional resources (Craik & Simon, 1980), a slowing of component processing operations (Salthouse, 1980), or a reduction in the capacity of the workspace in working memory (Baddeley, 1986). Each one of these positions has been productive in the sense of generating testable hypotheses, though it has never been clear that these are distinctive proposals. Rather, they seem to represent conceptual systems that translate easily into one other (Salthouse, 1991), and thus, show considerable overlap in their predictive power. The Inhibition Hypothesis (Hasher & Zacks, 1988), however, represents a significant departure from this state of affairs. Within the Inhibition framework, aging does not entail a decrease in capacity per se, but rather a failure of inhibitory mechanisms that regulate into working memory the entrance of information that is relevant to current comprehension goals. The upshot of this formulation is that a lack of efficiency in later adulthood is thought to be the result of too much information residing in working memory rather than too little! Interestingly, the Inhibition Hypothesis can handily account for any data that a reduced-capacity model (e.g., working memory, slowing, attentional capacity) can, since an ineffective modulation of the kind of information admitted into working memory would functionally decrease capacity by allowing irrelevant ideas to consume resources needed for 'goal-relevant' activities. In addition to accounting for the large body of data supporting the notion of age-related capacity limits, the Inhibition Hypothesis makes the rather unintuitive prediction that older adults will remember some things that younger adults would not, since the contents of their working memories are in some ways more 'enriched.' There is a growing body of
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literature which supports this. With respect to discourse processing, older adults seem less facile than the young in revising their memory representations (Zacks, Hasher, Doren, Hamm, & Attig, 1987). For example, Hartman and Hasher (1991) presented a series of sentences with highly predictable endings (e.g., "She ladled the soup into her -.'I), asking subjects to generate their own endings before the sentence-final words were presented. For some of the trials, these words were not the predicted ones (e.g., bowl), but were unexpected endings (e.g., lap). While younger adults demonstrated retention of only the presented endings in a subsequent test of indirect memory, older adults seemed to retain both endings. A similar finding was shown at the passage level in a study by Hamm and Hasher (1992). Subjects read passages which implied an inference (e.g., the reader is led to believe that the main character is in a hospital: she was ill, called her friend who was a nurse, and subsequently entered a large building) which is inconsistent with the later text (e.g., the fact that she goes to the main desk to check out a book). By the end of the passage, younger adults, when explicitly asked, have revised their previously incorrect inference (e.g., they report that she is in a library); in contrast, older adults were equally likely to report both the first inference suggested and the second (e.g., she is in a library and a hospital). Such age differences in discourse memory are hard to explain simply in terms of reduced capacity, but are easily explicable within the Inhibition framework. This notion is also consistent with the observation that older adults show disproportionate recall of less memorable idea units in high load conditions (Stine & Wingfield, 1990) and tend to produce more elaborations during text recall (e.g., Gould, Trevithick, & Dixon, 1991). One question that remains to be fully addressed is whether the failure of inhibition represents an inability to discriminate between the relevant and the irrelevant or an inability to focus on that which exceeds a threshold for relevance (cf. Stine & Wingfield, 1990). The Inhibition Hypothesis might also be useful in accounting for age differences in prospective memory. Certainly in planning what we are going to do and how we are going to accomplish it, we generate many alternatives. The Inhibition Hypothesis would predict that inadequate suppression of rejected alternatives would make it difficult to sort out and enact in due course the selected action or sequence of actions without some external aid. The finding by Cohen and Faulkner (1989) that older adults are more likely than the young to believe that they had actually performed actions which they had in fact only
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imagined performing is certainly consistent with this view. To sum up, any account of memory and aging must ultimately account for the reliable age differences found in performance. Many of the empirical findings in both discourse memory and prospective memory can be accommodated by the assumption that older adults have less effective inhibitory mechanisms. While intuitively it might seem that memory and aging research will best proceed by finding the cause of deficits and subsequently developing remediations, in the next section it is argued that this process also works in reverse; that is, effective remediation may give us some insight into cause.
Molar equivalence-molecular decomposition Almost a decade ago, Salthouse (1984) made a forceful case for the use of a research strategy he termed "molar equivalence-molecular decomposition. " The general principle is to measure a molar behavior among a sample of individuals for whom there is no change in performance as a function of age, and then to measure a set of molecular processes which presumably contribute to the molar behavior. Given molar equivalence across age groups, the research question then becomes what changes in the balance of the molecular processes enable age equivalence at the molar level. Note that this strategy of understanding molecular change in the face of molar stability departs from the strategy of localizing deficits in order to develop remedial strategies. In order to localize deficits we typically consider the consequences of variations in stimulus materials, subject characteristics, and task requirements on performance. Thus, we control and manipulate the former three sets of variables and treat level of performance (as speed or accuracy) as a dependent variable. This research strategy is, of course, a sound one for detailing the conditions under which age differences are exacerbated or minimized. An alternative approach is to consider the conditions which engender particular performance levels. A case in point is psychophysics in which the search for "molar equivalence" is the normative approach. For example, auditory sensitivity is described in terms of the sound pressure level (in dB) required in order to detect a pure tone of a particular frequency. That is, the dependent variable is the intensity required to achieve molar equivalence (i.e., threshold) which must be relatively greater for the detection of frequencies
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outside an intermediate range ( 5 2 k H z ) for young and old and especially great for high frequencies among the old (cf. Fozard, 1990). This parametric approach to understanding the limits of the information processing system is something that we take for granted in the area of psychophysics, and it is clear that our understanding of the auditory system would be very meager if we presented tones of varied frequency at a single arbitrary intensity level and simply reported the existence of relative 'deficits' for some frequencies which are exacerbated among the elderly. The difference in perspective is perhaps subtle. For example, while I agree with the substance of Cohen's account of age differences in prospective memory, I wish to take issue with the characterization that "the appearance of well-preserved prospective memory in old age is illusory." To the contrary, prospective memory is preserved in later adulthood, and this is accomplished by a skillful reliance on external aids. It is the assumption that memory is something one has that leads us to conclude that the elderly are wanting, while the assumption that memory is something one does would lead us to the conclusion that the older adult who has to remember a doctor's appointment is doing what is required to accomplish that goal. The objection is not merely an issue of rhetoric, but rather of framing the research agenda for memory and aging. Memory as doing can be seen in the literature on discourse memory. For example, in a self-paced word-by-word reading task, younger and older adults have been found to allocate time very similarly, with both groups slowing down to accommodate longer words as well as the organizational requirements of major and minor syntactic boundaries (Stine, 1990). With this similarity in on-line processing, subsequent memory performance for these single sentences show the typical memory advantage favoring the young. Age differences exist, however, in the patterns of reading time among those who show flawless recall of the sentences with older adults allocating differentially more time to the minor syntactic boundaries relative to major boundaries. Thus, in order to be successful in recall, the older readers may need to organize on-line into smaller chunks that are manageable within capacity limits. A more recent study (Stine & Cheung, unpublished data) demonstrates that older adults who show good recall of short narratives also handle the introduction of new concepts differently as well. In this study, subjects (n=24 in each age group) read three short narratives word-by-word for immediate
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recall. In order to focus on the effects of new concepts on reading time, reported times are those adjusted for the effects of word length, word frequency, and line breaks; thus, in these data these effects were statistically controlled to give cleaner estimates of new concepts effects. For younger and older adults, reading times for individual words systematically increased as a function of the number of new concepts that had been introduced into the text up to that point. This finding is consistent with the literature (Haberlandt, Graesser, Schneider, & Kiely, 1986) and illustrates the on-line processing effort that is required to assimilate new information into the current text representation. Interestingly, readers slow down to accommodate new concepts as soon as they are encountered (supporting an immediacy hypothesis), as well as at subsequent syntactic boundaries (supporting the notion that some information must be buffered, for example to organize the interrelationships among these new concepts). In the Stine and Cheung experiment, reading times were examined separately for young and elderly adults who showed higher and lower levels of recall performance, as determined by a median split on recall scores. Younger adults whose recall was below the median allocated an extra 8 msec per new concept at non-boundary sites within the sentence, an extra 21 msec per concept at constituent boundaries within sentences, and an extra 80 sec per concept at sentence boundaries. Younger adults who demonstrated higher levels of recall allocated an extra 28 msec per concept at non-boundary sites, an extra 135 msec per concept at constituent boundaries, and an extra 170 msec per concept at sentence boundaries. Thus, successful processing among the young entailed more thorough processing of new concepts at every level of the discourse hierarchy. Older adults who showed lower recall allocated 16 msec per concept at non-boundary sites, 38 msec per concept at constituent boundaries, and 55 msec per boundary at sentence boundaries (though this latter value was only marginally significant). Older adults with relatively higher levels of recall showed a non-significant effect of concept at non-boundary sites of 5 msec per concept, but allocated 56 msec per concept at constituent boundaries and 40 msec per concept at sentence boundaries (though again this sentence effect was only marginally significant). Unlike success among the young, successful memory performance of the old entailed additional processing at syntactic constituents within the sentence without further integration of new concepts at sentence boundaries.
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One caveat with respect to these findings is that the older adults' recall was lower than that of the young within each of the recall groups, thus "success" is necessarily defined within each age group. One might speculate as to the effects that various modes of instruction or structural supports (e.g., headings, signalling) might have on the allocation of reading time and subsequent recall and the adaptations that would be necessary among the old to bring their recall performance to be on par with the young; these issues will be important in future research. To this point, the discussion has been focussed on adaptations in strategy over the life-span that would have to accommodate capacity limits; we could call these 'constructed strategies. ' Expertise within a domain also represents development of constructed strategies. While expertise has been shown to mitigate age effects in some domains (e.g., older typists maintain their level of typing speed by looking farther ahead in the text, thus compensating for a slowing in choice reaction time), there has been very little research done on the role of domain expertise in text processing. The literature on the use of schematic information generally shows either the same or greater reliance on conceptually-driven processing among the older as among the young (Arbuckle, Vanderleck, Harsany, & Lapidus, 1990; Hess, 1990; Zelinski & Miura, 1988). In a recent study of the role of expertise in aviation on the processing of aviation narratives, Morrow, Leirer, and Altieri (1992) demonstrate similar effects of expertise across age groups; that is, even though expertise did not reduce age differences, older adults were able to take advantage of their expertise in aviation in order to process narratives relevant to their domain of expertise. In contrast to strategies that are developed over the course of the life-span, there are strategies that are essentially in place from very early on, which take on more importance later in the life-span (cf. Wingfield & Stine, 1991); we could call these 'default strategies.' For example, in speech processing, older adults appear to especially rely on the prosodic contour (e.g., intonation, pauses) for comprehension and syntactic analysis (Stine & Wingfield, 1987; Wingfield, Lahar, & S h e , 1989; Wingfield, Wayland, & Stine, 1992). Similarly, older adults are particularly dependent upon sentential context for word recognition (Madden, 1988; Wingfield, Aberdeen, & Stine, 1991). It is certainly not the case that prosodic and semantic contextual support suddenly take on importance in the cognitive system in later adulthood. Rather,
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such top-down processing strategies are in place much earlier in the life-span; as the quality of the product of bottom-up analysis is degraded (e.g., by sensory failures of the sensory system or by less effective inhibition), default strategies enable functional processing capacity to withstand (to some extent) the assaults of biological aging (cf. Wingfield & Stine, 1991).
Conclusions Thus, it is encouraging to note the diversity of methodologies applied to the study of adult age differences in prospective memory and discourse memory. The startling fact about these two domains of functioning is that in many ways they appear to be fairly well preserved into later adulthood. Perhaps, the extension of the study of expertise into these domains as well as a wider application of the molar equivalence-molecular decomposition strategy will shed light on the extraordinary level of competence that is maintained well into late life.
Acknowledgements. This commentary has been supported by Grant R29 AGO8382 from the National Institute on Aging. I am grateful to Daniel Henderson, Ken Fuld, and Bob Logie for helpful comments on an earlier draft of this manuscript. References Arbuckle, T. Y., Vanderleck, V. F., Harsany, M., & Lapidus, S . (1990). Adult age differences in memory in relation to availability and accessibility of knowledge-based schema. Journal of ExDerimental Psvchology: Learning. Memory. and Cognition, 16,305-315. Baddeley, A. D. (1986). University Press.
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Baltes, P. B., & Baltes, M. M. (1990). Psychological perspectives on successful aging: The model of selective optimization with compensation. In P. B. Baltes & M. M. Baltes (Eds.), Successful aging (pp. 1-34). New York: Cambridge University Press. Cavanaugh, J. C., & Green, E. E. (1990). I believe, therefore I can:
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Self-efficacy beliefs in memory and aging. In E. A. Lovelace (Ed.), Aging and cognition: Mental Drocesses. self-awareness and interventions (pp. 189-230). Amsterdam: North-Holland. Cavanaugh, J. C., & Poon, L. W. (1989). Metamemorial predictors of memory performance in young and old adults. Psychologv and Aging, 4, 365-368. Cohen, G., & Faulkner, D. (1989). Age differences in source forgetting: Effects on reality monitoring and on eye witness testimony. Psychology and Aging, 4, 1-8. Craik, F. I. M., & Simon, E. (1980). Age differences in memory: The role of attention and depth processing. In L. W. Poon, J. L. Fozard, L. S . Cermak, D. Arenberg, & L. W. Thompson (Eds.), New directions in memory and aging: Proceedings of George A. Talland memorial conference (pp. 95-1 12). Hillsdale, NJ: Lawrence Erlbaum. Cronbach, L. J. (1957). The two disciplines of scientific psychology. American Psychologist, 12, 671-684. Daneman, M., & Carpenter, P. A. (1980). Individual differences in working memory and reading. Journal of Verbal Learning and Verbal Behavior, B, 450-466. Daneman, M., & Carpenter, P. A. (1983). Individual differences in integrating information between and within sentences. Journal of Experimental Psychology: Learning. Memory. and Cognition, 9, 56 1-584. Daneman, M., & Tardif, T. (1987). Working memory and reading skill re-examined. In M. Coltheart (Ed.), Attention and Derformance. Vol. 12: TheDsychology of reading (pp. 491 -508). Hillsdale, NJ: Erlbaum. Fozard, J. L. (1990). Vision and hearing in aging. In J. E. Birren & K . W. Schaie (Eds.), Handbook of the psychologv of aging (pp. 150-170). New York: Academic Press. Gould, 0. N., Trevithick, L., & Dixon, R. A. (1991). Adult age differences in elaborations produced during prose recall. Psychology and Aging, 6, 93-99. Haberlandt, K. F., Graesser, A. C., Schneider, N. J., & Kiely, J.
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(1986). Effects of task and new arguments on word reading times. Journal of Memory and Language, 25, 314-322. Hamm, V. P., & Hasher, L. (1992). Age and the availability of inferences. Psvchologv and Aging, 2,56-64. Hartman, M., & Hasher, L. (1991). Aging and suppression: Memory for previously relevant information. Psychologv and Aging, 6, 587-594. Hasher, L., & Zacks, R. T. (1979). Automatic and effortful processes in memory. Journal of Experimental Psycholoev: General, 1Qs,356-388. Hasher, L., & Zacks, R. T. (1988). Working memory, comprehension and aging: A review and a new view. In G . H. Bower (Ed.), The psychology of learning and motivation, Vol. 22 (pp. 193-225), New York: Academic Press. Hess, T. M. (1990). Aging and schematic influences on memory. In T. M. Hess (Ed.), Aging and cognition: Knowledge organization and utilization (pp. 93-160) Amsterdam: North-Holland. Hunt, E., Lunneborg, C . , & Lewis, J. (1975). What does it mean to be high verbal? Cognitive Psycholoev, 7, 194-227. Lachrnan, M. E. (1983). Perceptions of intellectual aging: Antecedent or consequence of intellectual functioning. DeveloDmental Psycholoa, 19, 482-498. Madden, D. J. (1988). Adult age differences in the effects of sentence context and stimulus degradation during visual word recognition. Psychology and Aging, 3, 167-172. Morrow, D. G., Leirer, V. O., & Altieri, P. A. (1992). Aging, expertise, and narrative processing. Psvchology and Aging, 2,376-388. Nelson, E. A., & Dannefer, D. (1992). Aged heterogeneity: Fact or fiction? The fate of diversity in gerontological research. The Gerontologist, 32, 17-23. Otero, J., & Kintsch, W. (1992). Failures to detect contradictions in a text: What readers believe versus what they read. Psychological Science, 3, 229-235.
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Rowe, J. W., & Kahn, R. L. (1987). successful. Science, 237, 143-149.
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Salthouse, T. A. (1980). Age and memory: Strategies for localizing the loss. In L. W. Poon, J. L. Fozard, L. S . Cermak, D. Arenberg, & L. W. Thompson (Eds.), New directions in memory and aging: Proceedings of the George A. Talland memorial conference (pp. 47-65). Hillsdale, NJ: Erlbaum. Salthouse, T. A. (1984). Effects of age and skill in typing. Journal of Experimental Psychology: General, 113,345-371. Salthouse, T . A. (1991). Theoretical DersDectives on cognitive aging. Hillsdale, NJ: Erlbaum. Salthouse, T . A., & Babcock, R. L. (1991). Decomposing adult age differences in working memory. Developmental Psychology, 22, 763-776. Stine, E. A. L. (1990). On-line processing of written text by younger and older adults. Psychology and Aging, 5, 68-78. Stine, E. A. L . , & Hindman, J. (in press). Age differences in reading time allocation for propositionally dense sentences. Aging and Cognition. Stine, E. A. L., Lachman, M., & Wingfield, A. (in press). The roles of perceived and actual control in memory for spoken language. Educational Gerontology. Stine, E. A. L., & Wingfield, A. (1987). Process and strategy in memory for speech among younger and older adults. Psychologv and Aging, 2, 272-279. Stine, E. A. L., & Wingfield, A. (1990). The assessment of qualitative age differences in discourse processing. In T. M. Hess (Ed.), Aeing and cognition: Knowledge organization and utilization (pp. 33-92) New York: Elsevier. Stine, E. A. L., Wingfield, A., & Myers, S. D. (1990). Age differences in processing information from television news: The effects of bisensory augmentation. Journal of Gerontoloev: Psychological Sciences, 45, P1-8.
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Tun, P. A., Wingfield, A., & Stine, E. A. L. (1991). Speech processing capacity in younger and older adults: A dual-task study. P s v c h o l o g v g , 6, 3-9. Wingfield, A., Aberdeen, J. S., & Stine, E. A. L. (1991). Word-onset gating and linguistic context in spoken word recognition by young and elderly adults. Journal of Gerontology: Psychological Sciences, 46,P127-129. Wingfield, A., Lahar, C. J., & Stine, E. A. L. (1989). Age and decision strategies in running memory for speech: Effects of prosody and linguistic structure. Journal of Gerontology: Psychological Sciences, 44, P106-113. Wingfield, A., & Stine, E. A. L. (1991). Expert systems in nature: Spoken language processing and adults aging. In J. D. Sinnott & J. C. Cavanaugh (Eds.), Bridging paradigms: Positive development in adulthood and cognitive aging (pp. 237-258). New York: Praeger.
Wingfield, A., Wayland, S. C., & Stine, E. A. L. (1992). Adult age differences in the use of prosody for syntactic parsing and recall of spoken sentences. 1 47, P350-356. Zacks, R. T., Hasher, L., Doren, B., Hamm, V., & Attig, M. S. (1987). Encoding and memory of explicit and implicit information. Journal of Gerontology, 42, 418-422. Zelinski, E., & Miura, S. (1988). Effects of thematic information on script memory in young and old adults. Psvcholopy and Aging, 3, 292-299.
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Commentary: Is Memory Something We Have or Something We Do? Elizabeth A. L. Stine University of New Hampshire, U S A As Cohen accurately observes, the focus in much of the published research on memory and aging has been to characterize the conditions which engender age deficits in performance. An assumption underlying much of this literature is that memory is an endogenous trait, something one has, much like hair color or income or a car with an engine of a certain horsepower or a house of a particular size, and that the predominant task of cognitive aging has been to describe ’how much memory’ one has left in late adulthood. In the next few pages, I will use Cohen’s excellent chapter as a starting point from which to argue that memory is not only something we have, but that it is also something we do. While we may possess a home of a certain size and style, the point of having a home is to live in it; we arrange fuiniture and shelving and pictures and flower gardens so that it accommodates our lifestyle. Similarly, at any point in the life-span, our memory systems have certain limits (at a younger age these tend to be limits of knowledge base, while at an older age these tend to be limits of processing capacity), but somehow we manage to live within these limits so as to function in everyday life. While focusing on localization of deficits, memory and aging research has substantially neglected what it is that one must do in order to effectively use one’s memory capabilities into later adulthood. Thus, even though it is clear that there is substantial heterogeneity in the elderly population (Nelson & Dannefer, 1992), and that for some, aging is indeed ’successful’ (Baltes & Baltes, 1990; Rowe & Kahn, 1987), it is not at all clear how this is accomplished in the cognitive domain.
Methodological diversity Cohen aptly notes the wide variety of methods used in the study of memory and aging, categorizing them into phenomenological, psychometric, and experimental approaches. Such diversity will certainly prove to be an asset in untangling the phenomenon of successful cognitive aging. Cronbach (1957) noted some time ago that experimental psychology, which relies on tight control
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of situational variables, and correlational psychology, whose "mission is to observe and organize the data from Nature's experiments" (p. 672), seemed to represent two distinct disciplines within psychology ("The personality, social, and child psychologists went one way; the perception and learning psychologists went the other; and the country between turned into desert" (p. 675)). As he wrote this, he noted some tenuous lines of rapprochement, but called for a "true federation" (p. 675) that would acknowledge that "organism and treatment are an inseparable pair" (p. 683). The field of cognitive aging may well represent the psychology of Cronbach's dreams: growing from the experimentally-driven information processing tradition and the correlationally-driven tradition of developmental psychology, it must necessarily inhabit what used to be that desert in between. Perhaps one of the simplest ways in which this divide has been bridged is through the application of a psychometric (individual differences) approach to cognitive constructs. This has been a notable turn within the field of cognitive psychology whose overriding mission had been to describe general principles for the structure and process underlying mental phenomena. For example, Hunt's work demonstrating processing differences between high- and low-verbal adults (Hunt, Lunneborg, & Lewis, 1975) and Daneman and Carpenter's development of the 'listening span' task as a measure of the efficiency of working memory processing (Daneman & Carpenter, 1980) were critical in leading the field away from almost exclusive focus on the 'generic cognitive processor.' That is, it is not simply the case that short-term memory has a limited capacity of '7+2.' Rather, the more general principle is that processing capacity is limited, and that the value of this limit is variable in the population -- and that this limit has implications for the effectiveness of more general cognitive functioning (Daneman & Carpenter, 1983; Daneman & Tardif, 1987; Hunt et al., 1975; Otero & Kintsch, 1992). In cognitive aging research, this blend of experimental and psychometric approaches is apparent in research which compares age effects among subgroups varying in the efficiency of working memory processing. For example, age differences in memory for language have been found to be reduced or negligible among those who are similar in working memory performance (Stine & Hindman, in press; Tun, Wingfield, & Stine, 1991). Similarly, Salthouse and colleagues (e.g., Salthouse & Babcock, 1991) have shown that measures of simple processing speed can account for a substantial
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portion of age variance in working memory processing, which in turn may mediate age deficits in language memory performance for single sentences (Stine & Wingfield, 1987), for television news (Stine, Wingfield, & Myers, 1990), and for extended radio narratives (Stine, Lachman, & Wingfield, in press). Thus, while the ecological validity of some psychometric tests may be low (as Cohen notes), theory-driven process measures may, in fact, be very useful in accounting for age deficits in memory for language under more naturalistic conditions. Finally, with respect to methodological issues, I wish to affirm Cohen's inclusion of phenomenological approaches, though I would depart somewhat from her position that these methods are necessarily limited or nonanalytic. While it is, of course, true that subjective beliefs of one's ability or memory performance may have little contact with reality, there has been a growing literature in the last few years exploring the relationship between the phenomenological experience of memory and memory performance. For example, in their review of the literature, Cavanaugh and Greene (1990) note that self-confidence in one's ability (self-efficacy) is predictive of perseverance in the face of challenges, the efficiency of analytic thinking in complex cognitive tasks, the tendency to visualize and rehearse strategies for successful performance, and the tempering of perceived stress in a challenging situation. To be sure, (as Cohen points out) our perceptions of memory ability may be optimistic, but Cavanaugh and Greene argue that such a rosy perception of cognitive ability is adaptive. In fact, beliefs about one's memory are often predictive of actual memory performance (e.g., Cavanaugh & Poon, 1989). In a similar vein, Lachman (1983) has shown that believing one's cognitive performance is controlled by internal factors is positively related to memory performance while believing that one's performance is affected by external factors is negatively related to performance. When a measure of working memory span is partialled from the correlation between perceived control and memory, this correlation is negligible (Stine et al., in press), suggesting that control beliefs may affect memory performance by modulating working memory processing. Thus, it is probably the case that phenomenology affects process. This methodological interplay is important since it carries phenomenological methods from the realm of the "merely descriptive" into a position of being an analytic tool. One might envision the strongest strides in
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memory and aging research being made by creative blends of experimental, psychometric, and phenomenological methods.
A word about deficits All three methodological approaches have been used to isolate age-related capacity limits, which must be accommodated in order to age successfully. For some time now, the field of cognitive aging has been driven by the search for an adequate metaphor to capture the empirical findings of loss, with the primary candidates revolving around some loss of capacity. Thus, the causal locus of age deficits in memory has been alternatively postulated to reside in a relative decline in effortful processing (Hasher & Zacks, 1979), a dearth of attentional resources (Craik & Simon, 1980), a slowing of component processing operations (Salthouse, 1980), or a reduction in the capacity of the workspace in working memory (Baddeley, 1986). Each one of these positions has been productive in the sense of generating testable hypotheses, though it has never been clear that these are distinctive proposals. Rather, they seem to represent conceptual systems that translate easily into one other (Salthouse, 1991), and thus, show considerable overlap in their predictive power. The Inhibition Hypothesis (Hasher & Zacks, 1988), however, represents a significant departure from this state of affairs. Within the Inhibition framework, aging does not entail a decrease in capacity per se, but rather a failure of inhibitory mechanisms that regulate into working memory the entrance of information that is relevant to current comprehension goals. The upshot of this formulation is that a lack of efficiency in later adulthood is thought to be the result of too much information residing in working memory rather than too little! Interestingly, the Inhibition Hypothesis can handily account for any data that a reduced-capacity model (e.g., working memory, slowing, attentional capacity) can, since an ineffective modulation of the kind of information admitted into working memory would functionally decrease capacity by allowing irrelevant ideas to consume resources needed for 'goal-relevant' activities. In addition to accounting for the large body of data supporting the notion of age-related capacity limits, the Inhibition Hypothesis makes the rather unintuitive prediction that older adults will remember some things that younger adults would not, since the contents of their working memories are in some ways more 'enriched.' There is a growing body of
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literature which supports this. With respect to discourse processing, older adults seem less facile than the young in revising their memory representations (Zacks, Hasher, Doren, Hamm, & Attig, 1987). For example, Hartman and Hasher (1991) presented a series of sentences with highly predictable endings (e.g., "She ladled the soup into her -.'I), asking subjects to generate their own endings before the sentence-final words were presented. For some of the trials, these words were not the predicted ones (e.g., bowl), but were unexpected endings (e.g., lap). While younger adults demonstrated retention of only the presented endings in a subsequent test of indirect memory, older adults seemed to retain both endings. A similar finding was shown at the passage level in a study by Hamm and Hasher (1992). Subjects read passages which implied an inference (e.g., the reader is led to believe that the main character is in a hospital: she was ill, called her friend who was a nurse, and subsequently entered a large building) which is inconsistent with the later text (e.g., the fact that she goes to the main desk to check out a book). By the end of the passage, younger adults, when explicitly asked, have revised their previously incorrect inference (e.g., they report that she is in a library); in contrast, older adults were equally likely to report both the first inference suggested and the second (e.g., she is in a library and a hospital). Such age differences in discourse memory are hard to explain simply in terms of reduced capacity, but are easily explicable within the Inhibition framework. This notion is also consistent with the observation that older adults show disproportionate recall of less memorable idea units in high load conditions (Stine & Wingfield, 1990) and tend to produce more elaborations during text recall (e.g., Gould, Trevithick, & Dixon, 1991). One question that remains to be fully addressed is whether the failure of inhibition represents an inability to discriminate between the relevant and the irrelevant or an inability to focus on that which exceeds a threshold for relevance (cf. Stine & Wingfield, 1990). The Inhibition Hypothesis might also be useful in accounting for age differences in prospective memory. Certainly in planning what we are going to do and how we are going to accomplish it, we generate many alternatives. The Inhibition Hypothesis would predict that inadequate suppression of rejected alternatives would make it difficult to sort out and enact in due course the selected action or sequence of actions without some external aid. The finding by Cohen and Faulkner (1989) that older adults are more likely than the young to believe that they had actually performed actions which they had in fact only
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imagined performing is certainly consistent with this view. To sum up, any account of memory and aging must ultimately account for the reliable age differences found in performance. Many of the empirical findings in both discourse memory and prospective memory can be accommodated by the assumption that older adults have less effective inhibitory mechanisms. While intuitively it might seem that memory and aging research will best proceed by finding the cause of deficits and subsequently developing remediations, in the next section it is argued that this process also works in reverse; that is, effective remediation may give us some insight into cause.
Molar equivalence-molecular decomposition Almost a decade ago, Salthouse (1984) made a forceful case for the use of a research strategy he termed "molar equivalence-molecular decomposition. " The general principle is to measure a molar behavior among a sample of individuals for whom there is no change in performance as a function of age, and then to measure a set of molecular processes which presumably contribute to the molar behavior. Given molar equivalence across age groups, the research question then becomes what changes in the balance of the molecular processes enable age equivalence at the molar level. Note that this strategy of understanding molecular change in the face of molar stability departs from the strategy of localizing deficits in order to develop remedial strategies. In order to localize deficits we typically consider the consequences of variations in stimulus materials, subject characteristics, and task requirements on performance. Thus, we control and manipulate the former three sets of variables and treat level of performance (as speed or accuracy) as a dependent variable. This research strategy is, of course, a sound one for detailing the conditions under which age differences are exacerbated or minimized. An alternative approach is to consider the conditions which engender particular performance levels. A case in point is psychophysics in which the search for "molar equivalence" is the normative approach. For example, auditory sensitivity is described in terms of the sound pressure level (in dB) required in order to detect a pure tone of a particular frequency. That is, the dependent variable is the intensity required to achieve molar equivalence (i.e., threshold) which must be relatively greater for the detection of frequencies
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outside an intermediate range ( 5 2 k H z ) for young and old and especially great for high frequencies among the old (cf. Fozard, 1990). This parametric approach to understanding the limits of the information processing system is something that we take for granted in the area of psychophysics, and it is clear that our understanding of the auditory system would be very meager if we presented tones of varied frequency at a single arbitrary intensity level and simply reported the existence of relative 'deficits' for some frequencies which are exacerbated among the elderly. The difference in perspective is perhaps subtle. For example, while I agree with the substance of Cohen's account of age differences in prospective memory, I wish to take issue with the characterization that "the appearance of well-preserved prospective memory in old age is illusory." To the contrary, prospective memory is preserved in later adulthood, and this is accomplished by a skillful reliance on external aids. It is the assumption that memory is something one has that leads us to conclude that the elderly are wanting, while the assumption that memory is something one does would lead us to the conclusion that the older adult who has to remember a doctor's appointment is doing what is required to accomplish that goal. The objection is not merely an issue of rhetoric, but rather of framing the research agenda for memory and aging. Memory as doing can be seen in the literature on discourse memory. For example, in a self-paced word-by-word reading task, younger and older adults have been found to allocate time very similarly, with both groups slowing down to accommodate longer words as well as the organizational requirements of major and minor syntactic boundaries (Stine, 1990). With this similarity in on-line processing, subsequent memory performance for these single sentences show the typical memory advantage favoring the young. Age differences exist, however, in the patterns of reading time among those who show flawless recall of the sentences with older adults allocating differentially more time to the minor syntactic boundaries relative to major boundaries. Thus, in order to be successful in recall, the older readers may need to organize on-line into smaller chunks that are manageable within capacity limits. A more recent study (Stine & Cheung, unpublished data) demonstrates that older adults who show good recall of short narratives also handle the introduction of new concepts differently as well. In this study, subjects (n=24 in each age group) read three short narratives word-by-word for immediate
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recall. In order to focus on the effects of new concepts on reading time, reported times are those adjusted for the effects of word length, word frequency, and line breaks; thus, in these data these effects were statistically controlled to give cleaner estimates of new concepts effects. For younger and older adults, reading times for individual words systematically increased as a function of the number of new concepts that had been introduced into the text up to that point. This finding is consistent with the literature (Haberlandt, Graesser, Schneider, & Kiely, 1986) and illustrates the on-line processing effort that is required to assimilate new information into the current text representation. Interestingly, readers slow down to accommodate new concepts as soon as they are encountered (supporting an immediacy hypothesis), as well as at subsequent syntactic boundaries (supporting the notion that some information must be buffered, for example to organize the interrelationships among these new concepts). In the Stine and Cheung experiment, reading times were examined separately for young and elderly adults who showed higher and lower levels of recall performance, as determined by a median split on recall scores. Younger adults whose recall was below the median allocated an extra 8 msec per new concept at non-boundary sites within the sentence, an extra 21 msec per concept at constituent boundaries within sentences, and an extra 80 sec per concept at sentence boundaries. Younger adults who demonstrated higher levels of recall allocated an extra 28 msec per concept at non-boundary sites, an extra 135 msec per concept at constituent boundaries, and an extra 170 msec per concept at sentence boundaries. Thus, successful processing among the young entailed more thorough processing of new concepts at every level of the discourse hierarchy. Older adults who showed lower recall allocated 16 msec per concept at non-boundary sites, 38 msec per concept at constituent boundaries, and 55 msec per boundary at sentence boundaries (though this latter value was only marginally significant). Older adults with relatively higher levels of recall showed a non-significant effect of concept at non-boundary sites of 5 msec per concept, but allocated 56 msec per concept at constituent boundaries and 40 msec per concept at sentence boundaries (though again this sentence effect was only marginally significant). Unlike success among the young, successful memory performance of the old entailed additional processing at syntactic constituents within the sentence without further integration of new concepts at sentence boundaries.
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One caveat with respect to these findings is that the older adults' recall was lower than that of the young within each of the recall groups, thus "success" is necessarily defined within each age group. One might speculate as to the effects that various modes of instruction or structural supports (e.g., headings, signalling) might have on the allocation of reading time and subsequent recall and the adaptations that would be necessary among the old to bring their recall performance to be on par with the young; these issues will be important in future research. To this point, the discussion has been focussed on adaptations in strategy over the life-span that would have to accommodate capacity limits; we could call these 'constructed strategies. ' Expertise within a domain also represents development of constructed strategies. While expertise has been shown to mitigate age effects in some domains (e.g., older typists maintain their level of typing speed by looking farther ahead in the text, thus compensating for a slowing in choice reaction time), there has been very little research done on the role of domain expertise in text processing. The literature on the use of schematic information generally shows either the same or greater reliance on conceptually-driven processing among the older as among the young (Arbuckle, Vanderleck, Harsany, & Lapidus, 1990; Hess, 1990; Zelinski & Miura, 1988). In a recent study of the role of expertise in aviation on the processing of aviation narratives, Morrow, Leirer, and Altieri (1992) demonstrate similar effects of expertise across age groups; that is, even though expertise did not reduce age differences, older adults were able to take advantage of their expertise in aviation in order to process narratives relevant to their domain of expertise. In contrast to strategies that are developed over the course of the life-span, there are strategies that are essentially in place from very early on, which take on more importance later in the life-span (cf. Wingfield & Stine, 1991); we could call these 'default strategies.' For example, in speech processing, older adults appear to especially rely on the prosodic contour (e.g., intonation, pauses) for comprehension and syntactic analysis (Stine & Wingfield, 1987; Wingfield, Lahar, & S h e , 1989; Wingfield, Wayland, & Stine, 1992). Similarly, older adults are particularly dependent upon sentential context for word recognition (Madden, 1988; Wingfield, Aberdeen, & Stine, 1991). It is certainly not the case that prosodic and semantic contextual support suddenly take on importance in the cognitive system in later adulthood. Rather,
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such top-down processing strategies are in place much earlier in the life-span; as the quality of the product of bottom-up analysis is degraded (e.g., by sensory failures of the sensory system or by less effective inhibition), default strategies enable functional processing capacity to withstand (to some extent) the assaults of biological aging (cf. Wingfield & Stine, 1991).
Conclusions Thus, it is encouraging to note the diversity of methodologies applied to the study of adult age differences in prospective memory and discourse memory. The startling fact about these two domains of functioning is that in many ways they appear to be fairly well preserved into later adulthood. Perhaps, the extension of the study of expertise into these domains as well as a wider application of the molar equivalence-molecular decomposition strategy will shed light on the extraordinary level of competence that is maintained well into late life.
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