Enrichment Effects on Adult Cognitive Development: Can the Functional Capacity of Older Adults Be Preserved and Enhanced?

In the paper

“For instance, research suggests that when individuals participate in a cognitive-training program, the beneficial effects on cognitive performance tend to be relatively narrow in scope, usually localized to the specific cognitive test that was trained (e.g., Ball et al., 2002; Willis et al., 2006; but see Tranter & Koutstaal, 2008).”

What the sources say

• Partly supported

  The COMMENT section reports improvements on multiple measures of the cognitive ability trained, without demonstrated transfer to everyday performance over two years. But the Measures section explicitly says outcomes were designed to assess an ability rather than performance on a specific test. The study also concerns older adults, not individuals generally. (LLM, conf=0.88)

  cites Ball et al., 2002 sourceExperimental — accuracy not yet measured
• Partly supported

  Training Effects on Cognitive Abilities (p. 6) reports lasting improvement in the cognitive ability each intervention targeted, supporting the claim that benefits were relatively narrow. But Outcome Measures (p. 4) assesses each ability with three tests, so the paper does not establish that benefits were usually confined to the specific test trained. The Comment (p. 8) also reports modest transfer to everyday function. (LLM, conf=0.86)

  cites Willis et al., 2006 sourceExperimental — accuracy not yet measured
• ?Not checked — no full text of the sourcecites Tranter & Koutstaal, 2008 source

In the paper

“Likewise, animal studies have shown major changes in a variety of mechanisms, such as neurogenesis (growth of new neurons), even in mature animals, as a function of changing environmental contingencies (e.g., Cotman, 1995; Kempermann, 2008).”

What the sources say

• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites Cotman, 1995
• Supported

  The section “A synthesis of nonspecific and specific regulatory mechanisms” (p. 5) reports that novel, complex environments robustly induced adult neurogenesis even in old mice. The Introduction (p. 2) also reports that exposure to a complex environment beginning in midlife maintained higher neurogenesis. These passages support the neurogenesis example attributed to Kempermann. (LLM, conf=0.93)

  cites Kempermann, 2008 source

In the paper

“At another level, compensation may occur by competition and rearrangements among relatively autonomous processing circuits, without explicit awareness on the part of the individual of how he or she is compensating (e.g., Cabeza, 2002; Colcombe, Kramer, Erickson, & Scalf, 2005; Park & Reuter-Lorenz, 2009; ReuterLorenz & Cappel, 2008; Salthouse, 1984; cf. Edelman, 1987).”

What the sources say

• ?Not checked — no full text of the sourcecites Cabeza, 2002 source
• ?Not checked — no full text of the sourcecites Colcombe, Kramer, Erickson, & Scalf, 2005 source
• Partly supported

  In “The Scaffolding Theory of Cognitive Aging” (page unavailable), the paper describes neural compensation as recruiting additional circuitry and developing new pathways when existing circuitry cannot meet task demands. This supports compensation through changes in neural circuits, but the passages do not establish competition among relatively autonomous circuits or say that compensation occurs without explicit awareness. (LLM, conf=0.84)

  cites Park & Reuter-Lorenz, 2009 sourceExperimental — accuracy not yet measured

In the paper

“When operating close to the limits of performance, individuals tend to experience substantial dropoffs in performance unless they exert sustained, deliberate efforts to maintain peak performance levels (Ericsson, 2006).”

What the sources say

• Partly supported

  The discussion on p. 685 links deliberate effort to continued improvement, and Figure 38.1 (p. 687) says that experts who stop regular deliberate practice may prematurely automate their performance. Neither passage says that people operating near performance limits tend to suffer substantial drop-offs without such effort; the discussion on p. 687 describes a stable plateau rather than a drop-off. (LLM, conf=0.85)

  cites Ericsson, 2006 sourceExperimental — accuracy not yet measured

In the paper

“The memory training and speedof-processing training did not show differential preservation, relative to controls.”

What the sources say

• Supported

  The Abstract (p. 2) reports that neither memory nor speed-of-processing training had a significant effect on self-reported IADL difficulty relative to controls. This supports the claim as a statement about everyday functioning; the paper separately reports preserved gains in the cognitive abilities each intervention trained. (LLM, conf=0.87)

  cites Willis et al., 2006 source

In the paper

“Willis et al. (2006) reported 5-year retest data on the sample, showing that training benefits were still observed after the longer retention interval.”

What the sources say

• Supported

  The Training Effects on Cognitive Abilities section (p. 6) states that each intervention's improvement in the trained ability was retained across five years. This supports the citing sentence's claim that training benefits were still observed at the five-year retest. (LLM, conf=0.93)

  cites Willis et al., 2006 source

In the paper

“For example, Willis et al. (2006) showed that reasoning training had 5-year lagged benefits on self-reported aspects of instrumental activities of daily living (IADL) by older adults (see also Wolinsky et al., 2006).”

What the sources say

• Supported

  Training Effects on Daily Functioning (p. 6) reports that, at year 5, the reasoning group had significantly less self-reported IADL difficulty than controls. The Comment (p. 8) says effects on function were not observed until the 5-year follow-up, supporting the description of a lagged benefit. (LLM, conf=0.94)

  cites Willis et al., 2006 source
• ?Not checked — no full text of the sourcecites Wolinsky et al., 2006 source

In the paper

“training in real-time strategy video games that entail learning and coordinating the implementation of a number of complex strategies can engender transfer to a variety of tasks that tap different aspects of executive-control processes”

What the sources say

• Supported

  The section on correlations between game performance and executive-control tasks reports transfer from Rise of Nations training to task switching, N-back focus switching, and visual short-term memory in older adults. It also describes the game as emphasizing planning, switching between tasks, and executing different strategies, matching the claim’s qualified wording that such training can engender transfer. (LLM, conf=0.91)

  cites Basak, Boot, Voss, & Kramer, 2008 source

In the paper

“Only the running-wheel and enriched groups showed increased cell proliferation and survival and neurogenesis following the interventions.”

What the sources say

• Partly supported

  The Results show increased surviving BrdU-labeled cells and neuronal markers in runners compared with controls; the Discussion also reports that enriched environments increase survival of newborn cells. But this study tested only runners and controls, not an enriched-environment group or other intervention groups, so it cannot establish that only the two named interventions increased all three outcomes. The supplied passages do not give page numbers. (LLM, conf=0.90)

  cites Van Praag, Christie, Sejnowski, and Gage (1999) sourceExperimental — accuracy not yet measured

In the paper

“Higher level of social activity has been associated with reduced risk of developing dementia in four prospective studies”

What the sources say

• ?Not checked — no full text of the sourcecites Fabrigoule et al., 1995 source
• Partly supported

  The Discussion reports that the paper’s social-activity factor was significantly associated with lower incident dementia risk. But the Discussion and Conclusions identify only two earlier prospective studies, one of which found no significant association for social isolation or support. The source therefore does not support the claim of four prospective studies showing reduced risk. Page numbers were not available in our copy. (LLM, conf=0.90)

  cites Scarmeas et al., 2001 sourceExperimental — accuracy not yet measured
• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites Wang et al., 2002

In the paper

“Animal research has clearly established that distress-inducing experience can have deleterious effects on brain structure and function”

What the sources say

• ?Not checked — no full text of the sourcecites McEwen, 1999 source
• Partly supported

  The paper reports hippocampal degeneration in ulcerated monkeys and discusses evidence of neural degeneration and disrupted hippocampal glucose utilization in rats. But the Discussion describes the link between prolonged stress and primate damage as tentative; it does not establish that distress-inducing experience caused both structural and functional impairment. (LLM, conf=0.85)

  cites Uno, Tarara, Else, Suleman, & Sapolsky, 1989 sourceExperimental — accuracy not yet measured

In the paper

“Given at least some evidence that training programs may be associated with improvements in functional status (e.g., Willis et al., 2006), it is certainly the case that the potential for reducing morbidity and dependence in older populations through long-term cognitive enrichment programs is real.”

What the sources say

• Supported

  The COMMENT (p. 7) reports limited evidence that cognitive training improved daily function: trained participants reported less difficulty with instrumental activities of daily living after five years than controls. The cautious wording of the cited clause matches the paper's characterization of the functional evidence as limited and modest (COMMENT, p. 8). The later statement about potential reductions in morbidity and dependence is the citing authors' own conclusion, not the clause attributed to this source. (LLM, conf=0.93)

  cites Willis et al., 2006 source

In the paper

“That is, training of skills relevant for one ability has not generally been found to improve performance on other abilities (e.g., Ball et al., 2002).”

What the sources say

• Partly supported

  The Comment section reports that training improved multiple measures of the specific cognitive ability trained, which supports the claim’s emphasis on ability-specific gains. It reports no generalization to everyday performance over two years, but does not establish the broader claim that training one ability generally fails to improve other cognitive abilities. (LLM, conf=0.81)

  cites Ball et al., 2002 sourceExperimental — accuracy not yet measured

In the paper

“Interestingly, these within-person correlations of stress and working memory may be larger than more traditional between-person correlations-that is, those that assess whether an individual with chronic high stress, on average, has lower working-memory performance than a person with chronic low stress levels (Sliwinski et al., 2006).”

What the sources say

• Partly supported

  The Results report a significant within-person stress effect on 2-back working-memory performance but no reliable between-person effect, supporting the general contrast. The Discussion explains that the between-person measure was daily stress, not chronic stress; the paper does not establish that the within-person correlations were larger in magnitude than correlations based on chronic stress. (LLM, conf=0.85)

  cites Sliwinski et al., 2006 sourceExperimental — accuracy not yet measured

In the paper

“Research on the relationship of stress to working-memory performance, for instance, finds reliable correlations of within-person variability of stress and working memory-that is, how ups and downs in stress within a person relate to ups and downs in working-memory performance (e.g., Sliwinski, Smyth, Hofer, & Stawski, 2006).”

What the sources say

• Supported

  The Abstract reports that within-person variability in stress predicted within-person variability in response times on a 2-back working-memory task in both younger and older adults. The Discussion likewise reports worse performance on high-stress than low-stress days. This supports the citing sentence’s description of linked within-person fluctuations. (LLM, conf=0.93)

  cites Sliwinski et al., 2006 source

In the paper

“exercise interventions have substantial benefits for cognitive function, particularly for aspects of fluid intelligence and executive function.”

In the paper

“maintaining a lifestyle that is intellectually stimulating predicts better maintenance of cognitive skills”

In the paper

“Other studies show that meaningful social engagement is also predictive of better maintenance of cognitive functioning in old age.”

In the paper

“The longitudinal evidence consistently shows that engaging in intellectually stimulating activities is associated with better cognitive functioning at later points in time.”

In the paper

“is associated with a reduced risk of developing Alzheimer's disease in late life.”

In the paper

“late-life cognitive changes can result in curtailment of activities.”

In the paper

“train strategic control over cognition that does show transfer to different task environments.”

In the paper

“there is a parallel literature suggesting that physical activity, and aerobic exercise in particular, enhances older adults' cognitive function.”

In the paper

“there is considerable epidemiological evidence that stress and chronic psychological distress are negatively associated with changes in cognition.”

In the paper

“cognitive-training studies have demonstrated that older adults can improve cognitive functioning when provided with intensive training in strategies that promote thinking and remembering.”

In the paper

“maintenance of chess expertise through actively playing chess produces life-span curves of chess performance that do not resemble the curves for standard working-memory tasks”

What the sources say

• ?Not checked — no full text of the sourcecites Roring & Charness, 2007 source

In the paper

“These types of weighting approaches have not been notably successful in increasing the predictive validity of activity scales for cognition or for cognitive change.”

In the paper

“The few prospective and retrospective studies that have examined relationships between physical activity and cognition over the longer term also tentatively suggest that benefits may extend over substantial periods of time.”

In the paper

“Although there are clearly a number of important unanswered questions, the literature reviewed thus far suggests a relatively robust effect of physical-activity training on cognition.”

In the paper

“It is also important to point out that not all observational studies have found a positive relationship between physical activity and cognition (Verghese et al., 2003; Wilson, Mendes de Leon, Barnes, et al., 2002; Wilson, Bennett, Bienias, et al., 2002; Yamada et al., 2003).”

What the sources say

• ?Not checked — no full text of the sourcecites Verghese et al., 2003 source
• ?Not checked — no full text of the sourcecites Wilson, Mendes de Leon, Barnes, et al., 2002 source
• ?Not checked — no full text of the sourcecites Wilson, Bennett, Bienias, et al., 2002 source

In the paper

“In summary, the human intervention studies we have reviewed, when considered along with the observational studies, suggest a moderate relationship between physical-activity training and improved cognition.”

In the paper

“results obtained thus far are equivocal with regard to whether possession of an e4 allele has a positive effect, negative effect, or no effect on the relationship between physical activity and cognition”

What the sources say

• ?Not checked — no full text of the sourcecites Abbott et al., 2004 source
• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites Larson et al., 2006
• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites Podewils et al., 2005

In the paper

“The studies reviewed above suggest a modest relationship between physical activity and cognition.”

In the paper

“The observational studies described above suggest a potentially important association between physical activity and cognition.”

In the paper

“Most of the available evidence on cognitive enrichment through an active lifestyle rests on retrospective reports of activity frequency (e.g., Hultsch et al., 1993).”

What the sources say

• ?Not checked — no full text of the sourcecites Hultsch et al., 1993 source

In the paper

“The bulk of the evidence on cognitive enrichment comes from prospective observational longitudinal designs, in which individuals are followed over time and activities and cognition are assessed at fixed time intervals.”

In the paper

“Although evidence favorable to the enrichment hypothesis is accumulating, three general research areas urgently require additional attention.”

In the paper

“It is also the case, with a few notable exceptions (e.g., Bherer et al., 2006; Edwards et al., 2002; Jennings et al., 2005; Kramer, Larish, et al., 1999; Stuss et al., 2007; Willis et al., 2006), that transfer-of-training effects are relatively narrow.”

What the sources say

• ?Not checked — no full text of the sourcecites Bherer et al., 2006 source
• ?Not checked — no full text of the sourcecites Edwards et al., 2002 source
• ?Not checked — no full text of the sourcecites Jennings et al., 2005 source

In the paper

“Most of the available evidence about cognitive enrichment relies on longitudinal panel designs, with fixed and infrequently spaced time intervals for measurement.”

In the paper

“They showed that training gains were just as likely with persons who showed prior history of age-related cognitive decline as they were with persons who had shown maintenance of functioning.”

What the sources say

• ?Not checked — no full text of the sourcecites Schaie and Willis, 1986 source

In the paper

“Belief-restructuring approaches on their own have not been shown to produce maintenance of training benefits (e.g., Lachman, Weaver, Bandura, Elliott, & Lewkowicz, 1992)”

What the sources say

• ?Not checked — no full text of the sourcecites Lachman et al., 1992 source

In the paper

“Recently, West, Bagwell, and Dark-Freudeman (2008) showed that an intervention that targeted negative age stereotypes and promoted self-efficacy-combined with strategy training-had beneficial effects on older adults' memory performance.”

What the sources say

• ?Not checked — no full text of the sourcecites West, Bagwell, and Dark-Freudeman, 2008 source

In the paper

“Jennings et al. (2005) showed transfer of training in their memory-control task to other memory tasks in which the same control processes were relevant to performance.”

What the sources say

• ?Not checked — no full text of the sourcecites Jennings et al., 2005 source

In the paper

“The available evidence does not permit a precise quantification of enrichment benefits for aging individuals and an aging society, from an economic perspective.”

In the paper

“However, there is relatively little evidence from studies following people who have experienced major interventions over long periods of time.”

In the paper

“The majority of software programs marketed as enhancing cognition or brain function lack supporting empirical evidence for training and transfer effects.”

In the paper

“With few exceptions, the main focus of research on cognitive enhancement has been cross-sectional in nature, providing a snapshot of the effectiveness of different interventions at different points in the life span.”

In the paper

“Research on adherence to lifestyle changes in different domains, including exercise, suggests that activities that increase a sense of agency and that provide mastery experiences are self-reinforcing and are most likely to lead to creation of the integrated and sustained lifestyle that is probably needed to realize cognitive enrichment.”

In the paper

“There is enough variability in designs, measures, and outcomes to render it difficult to make convincing claims about cognitive enrichment from available observational studies.”

In the paper

“Nor have such studies typically included genetic biomarkers that may be related to individual differences in neurogenesis, synaptogenesis, and the like that may set the stage for benefits from cognitively enriching activities.”

In the paper

“With respect to transfer effects, cognitive-enrichment effects due to exercise have been observed to be substantially broader than those observed for most cognitive-training protocols (e.g., Colcombe & Kramer, 2003).”

What the sources say

• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites Colcombe & Kramer, 2003

In the paper

“There is some evidence that complexity of work and its intellectual demands may be related to better cognitive development in midlife and old age (Schooler et al., 1999).”

What the sources say

• ?Not checked — no full text of the sourcecites Schooler et al., 1999 source

In the paper

“Years ago, Schaie and Willis (1986) demonstrated the benefits of conducting training research on persons with wellcharacterized histories of cognitive change, assessed longitudinally.”

What the sources say

• ?Not checked — no full text of the sourcecites Schaie and Willis, 1986 source

In the paper

“According to this framework, the undeniable presence of age-related decline in cognition does not invalidate the view that behavior can enhance cognitive functioning.”

In the paper

“upper limits of performance are constrained by the boundaries created by biological aging.”

In the paper

“levels of performance are malleable and open to enhancement throughout the human life span”

In the paper

“We conclude that, on balance, the available evidence favors the hypothesis that maintaining an intellectually engaged and physically active lifestyle promotes successful cognitive aging.”

In the paper

“the potential for positive change, or plasticity, is maintained in adult cognition.”

In the paper

“the hypothesis that an active lifestyle that requires cognitive effort has long-term benefits for older adults' cognition is at least consistent with the available data.”

In the paper

“These studies suggest that there is considerable reserve potential in older adults' cognition that can be enhanced through training.”

In the paper

“the course of normal aging shapes a zone of possible functioning, which reflects person-specific endowments and age-related constraints.”

In the paper

“Individuals influence whether they function in the higher or lower ranges of this zone by engaging in or refraining from beneficial intellectual, physical, and social activities.”

In the paper

“representing a plausible brain substrate for the observed effects of aerobic exercise and other activities on cognition.”

In the paper

“cognition in the real world is, in our view, usually influenced by relevant knowledge structures”

What the sources say

• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites Bartlett, 1932
• ?Not checked — no full text of the sourcecites Ericsson & Kintsch, 1995 source
• ?Not checked — no full text of the sourcecites Masunaga & Horn, 2001 source

In the paper

“individuals at any given age operate within ranges of cognitive functioning that generally do not approximate their maximum performance potential”

What the sources say

• ?Not checked — no full text of the sourcecites Brim, 1992

In the paper

“tasks closely tied to sensory functioning (e.g., recognizing objects in a dark-adapted environment) will be more at risk for declining functioning due to age-related changes in sensation and perception”

What the sources say

• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites Nagel, Werkle-Bergner, Li, & Lindenberger, 2007
• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites Schneider & Pichora-Fuller, 2000

In the paper

“data-quality limitations place performance-specific constraints on older adults' cognitive performance for reasons having little to do with cognitive mechanisms per se.”

In the paper

“Age changes in functional attentional and workingmemory capacity can place major constraints on cognitive performance”

What the sources say

• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites Craik & Jennings, 1992
• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites Hultsch, Hertzog, Dixon, & Small, 1998
• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites Salthouse, 1991b

In the paper

“Some aspects of cognitive function, particularly those heavily imbued with knowledge or experience (what Baltes, 1997, refers to as the pragmatics of cognition), will be relatively well preserved in adulthood, provided that the performance context does not introduce performance-specific constraints due to challenges to impaired processing mechanisms”

What the sources say

• ?Not checked — no full text of the sourcecites Baltes, 1997 source
• ?Not checked — no full text of the sourcecites Hertzog, 1989 source

In the paper

“an individual's level of function depends on the extent to which he or she has mastered procedural skills and relevant knowledge (i.e., expertise) needed to successfully undertake a given cognitive task.”

In the paper

“Individuals select particular areas in which they invest time, energy, and cognitive resources to gain knowledge and experience”

What the sources say

• ?Not checked — no full text of the sourcecites Ackerman, 2000 source
• ?Not checked — no full text of the sourcecites Ackerman & Rolfhus, 1999 source
• ?Not checked — no full text of the sourcecites Baltes, 1997 source

In the paper

“age-related changes in speed of information processing will constrain performance in timelimited decisions”

What the sources say

• ?Not checked — no full text of the sourcecites Birren, 1970 source
• ?Not checked — no full text of the sourcecites Salthouse, 1996 source

In the paper

“virtually all cognitive tasks (including tests of fluid intelligence) involve mixtures of basic cognitive mechanisms (processes) operating on relevant information structures (knowledge) using relevant procedures or algorithms”

What the sources say

• ?Not checked — no full text of the sourcecites Hertzog, 2008 source
• ?Not checked — no full text of the sourcecites Hunt, 1978 source

In the paper

“Biological constraints on the possible range of functioning increase to different degrees with aging, depending on what types of processing mechanisms or knowledge structures are involved.”

In the paper

“In sum, cognitive-enrichment effects can occur in the face of, and perhaps even despite, normative changes in the mechanisms often studied by cognitive psychologists.”

In the paper

“An important implication of this argument is that older adults often achieve excellent levels of functioning in everyday life in tasks that seem to require cognitive mechanisms that have declined.”

In the paper

“In response to developmental losses in cognitive mechanisms over the adult life course, individuals can choose different processing strategies when a particular mode of processing no longer achieves desirable outcomes.”

In the paper

“cognitive development over the life course is likely to involve compensatory adaptations to age or experience-related change in the form of shifting cognitive procedures or strategies”

What the sources say

• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites Bäckman & Dixon, 1987
• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites Baltes, Maas, Wilms, Borchelt, & Little, 1999
• ?Not checked — no full text of the sourcecites Hertzog, 1985 source

In the paper

“Curve C suggests that late-life improvement in cognitive functioning is possible if an individual engages in enrichment behaviors in midlife that are of a quality and degree not previously manifested at earlier ages, with those behaviors pushing the individual toward optimality.”

In the paper

“Such findings encourage us to view brain-behavior relationships as dynamic and reciprocal rather than as static and hierarchical (Lindenberger, Li, & Ba ¨ ckman, 2006b).”

What the sources say

• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites Lindenberger, Li, & Ba ¨ ckman, 2006b

In the paper

“at a given point in time there are multiple procedures available to an individual to achieve cognitive goals.”

In the paper

“In short, what appears to be a normative, biologically graded decline may reflect, to a major degree, inertial resistance to behaviors that could optimize development and set one on a different developmental trajectory.”

In the paper

“they may rely on different varieties of contextual support to overcome age-related processing limitations”

What the sources say

• ?Not checked — no full text of the sourcecites Bäckman, 1989 source
• ?Not checked — no full text of the sourcecites Craik & Byrd, 1982 source

In the paper

“Stability, in the sense of unchanging behavior, does not imply immutability (Caspi, Roberts, & Shiner, 2005; Kagan, 1999).”

What the sources say

• ?Not checked — no full text of the sourcecites Caspi, Roberts, & Shiner, 2005 source
• ?Not checked — no full text of the sourcecites Kagan, 1999 source

In the paper

“The inertia of maintaining a well-learned and nominally effective strategy at one point in the life course puts one at risk for failing to adaptively shift to a new and more effective strategy at a later point in time (Hertzog, 2008).”

What the sources say

• ?Not checked — no full text of the sourcecites Hertzog, 2008 source

In the paper

“there are typically multiple pathways by which effective problem solutions can be achieved”

What the sources say

• ?Not checked — no full text of the sourcecites Hunt, 1978 source
• ?Not checked — no full text of the sourcecites Lautrey, 2003

In the paper

“Contemporary neuroscience research suggests that individuals selected into particular environments show neuronal changes as a function of the specific cognitive-processing requirements of those environments (e.g., Maguire, Woollett, & Spiers, 2006).”

What the sources say

• ?Not checked — no full text of the sourcecites Maguire, Woollett, & Spiers, 2006 source

In the paper

“They may also rely on a variety of external aids that seek to reduce demands on compromised cognitive mechanisms”

What the sources say

• ?Not checked — no full text of the sourcecites Intons-Peterson & Fournier, 1986 source

In the paper

“In either case, compensatory behaviors are one means of mitigating effects of aging on basic cognitive mechanisms.”

In the paper

“Though past life histories certainly condition the range of aging outcomes to a more or less substantial degree, the present framework posits that any given age period offers a range of more or less desirable continuations of given developmental paths, depending on what happens in the age periods thereafter.”

In the paper

“As noted earlier, this can occur because of beneficialexpertise effects, but it can also occur because individuals develop strategic approaches to life tasks that minimize the role of cognitive mechanisms, per se, in achieving cognitive outcomes (Salthouse, 1991a).”

What the sources say

• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites Salthouse, 1991a

In the paper

“Moreover, the kinds of adaptation discussed above at the behavioral level may be paralleled in the neuronal substrate.”

In the paper

“older adults may use more intensive organizational strategies to support learning information when incidental learning makes spontaneous remembering of critical information less likely.”

In the paper

“In line with these findings, short-term training such as learning to juggle or studying for an academic exam has been found to induce structural alterations in the brain (Draganski et al., 2004, 2006).”

What the sources say

• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites Draganski et al., 2004, 2006

In the paper

“However, recent work indicates that individual differences in intraindividual change can be obscured in crosssectional data because of the contributions of other sources of variance in cognition.”

What the sources say

• ?Not checked — no full text of the sourcecites Hofer, Flaherty, & Hoffman, 2006 source
• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites Hultsch et al., 1998
• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites Lindenberger, von Oertzen, Ghisletta, & Hertzog, 2008

In the paper

“First, the cross-sectional method is not necessarily a good approximation of average developmental change, for a variety of methodological reasons (Schaie, 1977).”

What the sources say

• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites Schaie, 1977

In the paper

“In a sense, the likelihood of regression to the mean increases as an individual becomes more extreme in a distribution of scores (Nesselroade, Stigler, & Baltes, 1980).”

What the sources say

• ?Not checked — no full text of the sourcecites Nesselroade, Stigler, & Baltes, 1980 source

In the paper

“Third, the interpretation of activity-segregated cross-sectional data is further complicated by the fact that individuals in the high-activity groups usually perform above the level of the low-activity groups throughout all age periods considered, including the youngest age bracket.”

In the paper

“Logically, failing to find differential effects in crosssectional data constitutes a failure to reject a null hypothesis of parallel curves at different levels of activity.”

In the paper

“Thus, Activity -Age interaction effects may fail to emerge because individual differences in change due to different enrichment behaviors are overshadowed by the aggregate mean curves, making it difficult to detect the interaction effects.”

In the paper

“Second, even if one presumes that cross-sectional age trends approximate the mean or average age curve, this does not imply that partitioning cross-sectional trends by levels of activity provides strong evidence regarding the cognitive-enrichment hypothesis.”

In the paper

“During sensitive periods early in development, exposure to different environments is known to have long-lasting and largely irreversible effects on brain structure and function (cf. Hensch, 2004, 2005).”

What the sources say

• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites Hensch, 2004, 2005

In the paper

“The validity of such measures has usually not been directly assessed (e.g., by comparing questionnaire self-reports to other observations of activity levels).”

In the paper

“Although a qualitative distinction between normal aging and age-related pathology is part of the foundation of many theoretical discussions of aging (e.g., Baltes & Willis, 1977), clinical-pathological data suggest that the difference is mainly quantitative.”

What the sources say

• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites Baltes & Willis, 1977

In the paper

“In addition, general laws of learning (e.g., Thorndike, 1906) indicate that performance improvements are more difficult to obtain at high levels of cognitive skill.”

What the sources say

• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites Thorndike, 1906

In the paper

“In addition to their scope, enrichment effects also vary in their sustainability.”

In the paper

“For example, differential sampling and selection effects (including differential mortality in the population) can distort the cross-sectional curve (Nesselroade & Labouvie, 1985).”

What the sources say

• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites Nesselroade & Labouvie, 1985

In the paper

“However, especially at older ages, maintaining high performance levels may require greater ability-relevant behavioral investments than maintaining lower levels of performance.”

In the paper

“Such effects may be difficult to observe even if the assumptions of the cross-sectional method are fully met.”

In the paper

“Be that as it may, the practical utility of this kind of training for enhancing everyday life would be limited and indirect, at best.”

In the paper

“In this context, it should also be noted that measurements of activity levels are often based on self-reports and other indirect estimates of ability-relevant activities.”

In the paper

“For instance, individuals with higher cognitive abilities may use more conservative standards when judging the cognitive demands of their daily activities than might individuals with lower cognitive abilities (see Rabbitt, Maylor, McInnes, Bent, & Moore, 1995).”

What the sources say

• ?Not checked — no full text of the sourcecites Rabbitt, Maylor, McInnes, Bent, & Moore, 1995 source

In the paper

“Thus, the pathologic lesions most commonly associated with late-life dementia-amyloid plaques, neurofibrillary tangles, Lewy bodies, and cerebral infarctionare also seen in a substantial number of older person who die with mild cognitive impairment (Bennett, Schneider, Wilson, Bienias, & Arnold, 2005a; Guillozet, Weintraub, Mash, & Mesulam, 2003; Markesbery et al., 2006; Petersen et al., 2”

What the sources say

• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites Bennett, Schneider, Wilson, Bienias, & Arnold, 2005a
• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites Guillozet, Weintraub, Mash, & Mesulam, 2003
• ?Not checked — no full text of the sourcecites Markesbery et al., 2006 source

In the paper

“Thus, excluding persons with dementia or its precursor from aging studies does not eliminate age-related neuropathology or its deleterious impact on cognition.”

In the paper

“Accepting the null hypothesis is a risky inference about a small (in practical terms, a near-zero) effect size.”

In the paper

“Specifically, variance due to (a) age differences in (aggregate) mean performance and (b) stable individual differences may be more important contributors to cross-sectional variance in cognition than individual differences in intraindividual change (Hofer, Flaherty, & Hoffman, 2006; Hultsch et al., 1998; Lindenberger, von Oertzen, Ghisletta, & Hertzog, 2008).”

What the sources say

• ?Not checked — no full text of the sourcecites Hofer, Flaherty, & Hoffman, 2006 source
• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites Hultsch et al., 1998
• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites Lindenberger, von Oertzen, Ghisletta, & Hertzog, 2008

In the paper

“At minimum, it requires justification in terms of available statistical power, given the likelihood that true cognitive-enrichment effects will probably produce small interaction effect sizes.”