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1.	Bellander, Martin, et al. (författare) Lower baseline performance but greater plasticity of working memory for carriers of the val allele of the comt val158met polymorphism 2015 Ingår i: Neuropsychology. - : American Psychological Association (APA). - 0894-4105 .- 1931-1559. ; 29:2, s. 247-254 Tidskriftsartikel (refereegranskat)abstract Objective: Little is known about genetic contributions to individual differences in cognitive plasticity. Given that the neurotransmitter dopamine is critical for cognition and associated with cognitive plasticity, we investigated the effects of 3 polymorphisms of dopamine-related genes (LMX1A, DRD2, COMT) on baseline performance and plasticity of working memory (WM), perceptual speed, and reasoning. Method: One hundred one younger and 103 older adults underwent approximately 100 days of cognitive training, and extensive testing before and after training. We analyzed the baseline and posttest data using latent change score models. Results: For working memory, carriers of the val allele of the COMT polymorphism had lower baseline performance and larger performance gains from training than carriers of the met allele. There was no significant effect of the other genes or on other cognitive domains. Conclusions: We relate this result to available evidence indicating that met carriers perform better than val carriers in WM tasks taxing maintenance, whereas val carriers perform better at updating tasks. We suggest that val carriers may show larger training gains because updating operations carry greater potential for plasticity than maintenance operations.
2.	Berggren, Rasmus, et al. (författare) Foreign language learning in older age does not improve memory or intelligence : Evidence from a randomized controlled study. 2020 Ingår i: Psychology and Aging. - : American Psychological Association (APA). - 0882-7974 .- 1939-1498. ; 35:2, s. 212-219 Tidskriftsartikel (refereegranskat)abstract Foreign language learning in older age has been proposed as a promising avenue for combatting age-related cognitive decline. We tested this hypothesis in a randomized controlled study in a sample of 160 healthy older participants (aged 65-75 years) who were randomized to 11 weeks of either language learning or relaxation training. Participants in the language learning condition obtained some basic knowledge in the new language (Italian), but between-groups differences in improvements on latent factors of verbal intelligence, spatial intelligence, working memory, item memory, or associative memory were negligible. We argue that this is not due to either poor measurement, low course intensity, or low statistical power, but that basic studies in foreign languages in older age are likely to have no or trivially small effects on cognitive abilities. We place this in the context of the cognitive training and engagement literature and conclude that while foreign language learning may expand the behavioral repertoire, it does little to improve cognitive processing abilities. (PsycINFO Database Record (c) 2020 APA, all rights reserved).
3.	Brehmer, Yvonne, et al. (författare) The importance of the ventromedial prefrontal cortex for associative memory in older adults : A latent structural equation analysis 2020 Ingår i: NeuroImage. - : Elsevier BV. - 1053-8119 .- 1095-9572. ; 209 Tidskriftsartikel (refereegranskat)abstract Older adults show relatively minor age-related decline in memory for single items, while their memory for associations is markedly reduced. Inter-individual differences in memory function in older adults are substantial but the neurobiological underpinnings of such differences are not well understood. In particular, the relative importance of inter-individual differences in the medio-temporal lobe (MTL) and the lateral prefrontal cortex (PFC) for associative and item recognition in older adults is still ambiguous. We therefore aimed to first establish the distinction between inter-individual differences in associative memory (recollection-based) performance and item memory (familiarity-based) performance in older adults and subsequently link these two constructs to differences in cortical thickness in the MTL and lateral PFC regions, in a latent structural equation modelling framework. To this end, a sample of 160 older adults (65-75 years old) performed three intentional itemassociative memory tasks, of which a subsample (n = 72) additionally had cortical thickness measures in MTL and PFC regions of interest available. The results provided support for a distinction between familiarity-based item memory and recollection-based associative memory performance in older adults. Cortical thickness in the ventro-medial prefrontal cortex was positively correlated with associative recognition performance, above and beyond any relationship between item recognition performance and cortical thickness in the same region and between associative recognition performance and brain structure in the MTL (parahippocampus). The findings highlight the relative importance of the ventromedial prefrontal cortex in allowing for intentional recollection-based associative memory functioning in older adults.
4.	Brose, Annette, et al. (författare) Adult Age Differences in Covariation of Motivation and Working Memory Performance: Contrasting Between-Person and Within-Person Findings 2010 Ingår i: Research in Human Development. - : Informa UK Limited. - 1542-7609 .- 1542-7617. ; 7:1, s. 61-78 Tidskriftsartikel (refereegranskat)abstract Developmental theorists have proposed for a long time that the prevailing focus on stable individual differences has obstructed the discovery of short-term covariations between cognitive performance and contextual influences within individuals that may help to uncover mechanisms underlying long-term change. As an initial step to overcome this imbalance, we observed measures of motivation and working memory (WM) in 101 younger and 103 older adults across 100 occasions. Our main goals were to (1) investigate day-to-day relations between motivation and WM, (2) show that these relations differ between groups of younger and older adults, and (3) test whether the within-person and between-person structures linking motivational variables to WM are equivalent (i.e., the ergodicity assumption). The covariation between motivation and WM was generally positive in younger adults. In contrast, older adults showed reduced variability in motivation, increased variability across trials, and small reliability-adjusted correlations between motivation and WM. Within-person structures differed reliably across individuals, defying the ergodicity assumption. We discuss the implications of our findings for developmental theory and design, stressing the need to explore the effects of between-person differences in short-term covariations on long-term developmental change.
5.	Brose, Annette, et al. (författare) Daily Fluctuations in Positive Affect Positively Co-Vary With Working Memory Performance 2014 Ingår i: Emotion. - : American Psychological Association (APA). - 1528-3542 .- 1931-1516. ; 14:1, s. 1-6 Tidskriftsartikel (refereegranskat)abstract Positive affect is related to cognitive performance in multiple ways. It is associated with motivational aspects of performance, affective states capture attention, and information processing modes are a function of affect. In this study, we examined whether these links are relevant within individuals across time when they experience minor ups and downs of positive affect and work on cognitive tasks in the laboratory on a day-to-day basis. Using a microlongitudinal design, 101 younger adults (20-31 years of age) worked on 3 working memory tasks on about 100 occasions. Every day, they also reported on their momentary affect and their motivation to work on the tasks. In 2 of the 3 tasks, performance was enhanced on days when positive affect was above average. This performance enhancement was also associated with more motivation. Importantly, increases in task performance on days with above-average positive affect were mainly unrelated to variations in negative affect. This study's results are in line with between-person findings suggesting that high levels of well-being are associated with successful outcomes. They imply that success on cognitively demanding tasks is more likely on days when feeling happier.
6.	Brose, Annette, et al. (författare) Daily variability in working memory is coupled with negative affect : the role of attention and motivation 2012 Ingår i: Emotion. - : American Psychological Association (APA). - 1528-3542 .- 1931-1516. ; 12:3, s. 605-617 Tidskriftsartikel (refereegranskat)abstract Across days, individuals experience varying levels of negative affect, control of attention, and motivation. We investigated whether this intraindividual variability was coupled with daily fluctuations in working memory (WM) performance. In 100 days, 101 younger individuals worked on a spatial N-back task and rated negative affect, control of attention, and motivation. Results showed that individuals differed in how reliably WM performance fluctuated across days, and that subjective experiences were primarily linked to performance accuracy. WM performance was lower on days with higher levels of negative affect, reduced control of attention, and reduced task-related motivation. Thus, variables that were found to predict WM in between-subjects designs showed important relationships to WM at the within-person level. In addition, there was shared predictive variance among predictors of WM. Days with increased negative affect and reduced performance were also days with reduced control of attention and reduced motivation to work on tasks. These findings are in line with proposed mechanisms linking negative affect and cognitive performance.
7.	Brose, Annette, et al. (författare) Differences in the Between-Person and Within-Person Structures of Affect Are a Matter of Degree 2015 Ingår i: European Journal of Personality. - : SAGE Publications. - 0890-2070 .- 1099-0984. ; 29:1, s. 55-71 Tidskriftsartikel (refereegranskat)abstract This study tested whether the structure of affect observed on the basis of between-person (BP) differences is equivalent to the affect structures that organize the variability of affective states within persons (WP) over time. Further aims were to identify individual differences in the degree of divergence between the WP and BP structure and examine its association to dispositional and contextual variables (neuroticism, extraversion, well-being and stress). In 100 daily sessions, 101 younger adults rated their mood on the Positive and Negative Affect Schedule. Variability of five negative affect items across time was so low that they were excluded from the analyses. We thus worked with a modified negative affect subscale. WP affect structures diverged reliably from the BP structure, with individual differences in the degree of divergence. Differences in the WP structural characteristics and the degree of divergence could be predicted by well-being and stress. We conclude that BP and WP structures of affect are not equivalent and that BP and WP variation should be considered as distinct phenomena. It would be wrong, for example, to conceive of positive and negative affect as independent at the WP level, as suggested by BP findings. Yet, individual differences in WP structural characteristics are related to stable BP differences, and the degree to which individuals' affect structures diverge from the BP structure can provide important insights into intraindividual functioning.
8.	Brose, Annette, et al. (författare) Normal aging dampens the link between intrusive thoughts and negative affect in reaction to daily stressors 2011 Ingår i: Psychology and aging. - Arlington, VA : American Psychological Association (APA). - 0882-7974 .- 1939-1498. ; 26:2, s. 488-502 Tidskriftsartikel (refereegranskat)abstract We charted daily variations in intrusive thoughts to gain access to adult age differences in affective reactivity to daily stressors. On 100 days, 101 younger and 103 older adults reported stressors, intrusive thoughts, and negative affect. Although increments in intrusive thoughts were similar in both age groups on days with stressors, older adults' negative affect increased less than younger adults' on such days. In addition, (a) levels of intrusive thoughts and negative affect across study time were positively associated; (b) days with increased thoughts were days with increased negative affect; and (c) experiencing above-average intrusive thoughts about stressors strengthened affective reactions to stress. Relative to younger adults, all three associations were reduced in older adults. We tentatively conclude that normal aging dampens the stress-induced link between intrusive thoughts and affect. This dampening may contribute to preserved affective well-being and reduced affective reactivity to daily stress in old age.
9.	Grandy, Thomas H., et al. (författare) Individual alpha peak frequency is related to latent factors of general cognitive abilities 2013 Ingår i: NeuroImage. - : Elsevier BV. - 1053-8119 .- 1095-9572. ; 79, s. 10-18 Tidskriftsartikel (refereegranskat)abstract Some eighty years after the discovery of the human electroencephalogram (EEG) and its dominant rhythm, alpha (similar to 10 Hz), the neurophysiological functions and behavioral correlates of alpha oscillations are still under debate. Similarly, the biological mechanisms contributing to the general factor of intelligence, or g, have been under scrutiny for decades. Individual alpha frequency (IAF), a trait-like parameter of the EEG, has been found to correlate with individual differences in cognitive performance and cognitive abilities. Informed by large-scale theories of neural organization emphasizing the general functional significance of oscillatory activity, the present study replicates and extends these findings by testing the hypothesis that IAF is related to intelligence at the level of g, rather than at the level of specific cognitive abilities. Structural equation modeling allowed us to statistically control for measurement error when estimating the association between IAF and intellectual functioning. In line with our hypothesis, we found a statistically reliable and substantial correlation between IAF and g (r = .40). The magnitude of this correlation did not differ significantly between younger and older adults, and captured all of the covariation between IAF and the cognitive abilities of reasoning, memory, and perceptual speed. The observed association between IAF and g provides a parsimonious explanation for the commonly observed diffuse pattern of correlations between IAF and cognitive performance. We conclude that IAF is a marker of global architectural and functional properties of the human brain.
10.	Grandy, Thomas H., et al. (författare) Peak individual alpha frequency qualifies as a stable neurophysiological trait marker in healthy younger and older adults 2013 Ingår i: Psychophysiology. - : Wiley. - 0048-5772 .- 1469-8986 .- 1540-5958. ; 50:6, s. 570-582 Tidskriftsartikel (refereegranskat)abstract The individual alpha frequency (IAF) of the human EEG reflects systemic properties of the brain, is highly heritable, and relates to cognitive functioning. Not much is known about the modifiability of IAF by cognitive interventions. We report analyses of resting EEG from a large-scale training study in which healthy younger (2031 years, N=30) and older (6580 years, N=28) adults practiced 12 cognitive tasks for approximate to 100 1-h sessions. EEG was recorded before and after the cognitive training intervention. In both age groups, IAF (and, in a control analysis, alpha amplitude) did not change, despite large gains in cognitive performance. As within-session reliability and test-retest stability were high for both age groups, imprecise measurements cannot account for the findings. In sum, IAF is highly stable in healthy adults up to 80 years, not easily modifiable by cognitive interventions alone, and thus qualifies as a stable neurophysiological trait marker.
11.	Hertzog, Christopher, et al. (författare) Age Differences in Coupling of Intraindividual Variability in Mnemonic Strategies and Practice-Related Associative Recall Improvements 2017 Ingår i: Psychology and Aging. - : American Psychological Association (APA). - 0882-7974 .- 1939-1498. ; 32:6, s. 557-571 Tidskriftsartikel (refereegranskat)abstract The importance of encoding strategies for associative recall is well established, but there have been no studies of aging and intraindividual variability (IAV) in strategy use during extended practice. We observed strategy use and cued-recall test performance over 101 days of practice in 101 younger adults (M = 25.6 years) and 103 older adults (M = 71.3 years) sandwiched by a pretest and posttest battery including an associative recall test. Each practice session included 2 lists of 12 number-noun paired-associate (PA) items (e.g., 23-DOGS), presented for brief exposures titrated to maintain below-ceiling performance throughout practice. Participants reported strategy use (e.g., rote repetition, imagery) after each test. Substantial IAV in strategy use was detected that was coupled with performance; lists studied with normatively effective strategies (e.g., imagery) generated higher PA recall than lists studied with less effective strategies (e.g., rote repetition). In comparison to younger adults, older adults' practice (a) relied more on repetition and less on effective strategies, (b) showed lower levels of IAV in effective strategy use, and (c) had lower within-person strategy-recall coupling, especially late in practice. Individual differences in pretest-posttest gains in PA recall were predicted by average level of effective strategy use in young adults but by strategy-recall coupling in older adults. Results are consistent with the hypothesis that experiencing variability in strategic outcomes during practice helps hone the effectiveness of strategic encoding behavior, and that older adults' reduced degree of pretest-posttest gains is influenced by lower likelihood of using and optimizing effective strategies through practice.
12.	Kühn, Simone, et al. (författare) Brain areas consistently linked to individual differences in perceptual decision-making in younger as well as older adults before and after training 2011 Ingår i: Journal of cognitive neuroscience. - Cambridge, Mass. : MIT Press. - 0898-929X .- 1530-8898. ; 23:9, s. 2147-2158 Tidskriftsartikel (refereegranskat)abstract Perceptual decision-making performance depends on several cognitive and neural processes. Here, we fit Ratcliff's diffusion model to accuracy data and reaction-time distributions from one numerical and one verbal two-choice perceptual-decision task to deconstruct these performance measures into the rate of evidence accumulation (i.e., drift rate), response criterion setting (i.e., boundary separation), and peripheral aspects of performance (i.e., nondecision time). These theoretical processes are then related to individual differences in brain activation by means of multiple regression. The sample consisted of 24 younger and 15 older adults performing the task in fMRI before and after 100 daily 1-hr behavioral training sessions in a multitude of cognitive tasks. Results showed that individual differences in boundary separation were related to striatal activity, whereas differences in drift rate were related to activity in the inferior parietal lobe. These associations were not significantly modified by adult age or perceptual expertise. We conclude that the striatum is involved in regulating response thresholds, whereas the inferior parietal lobe might represent decision-making evidence related to letters and numbers.
13.	Kühn, Simone, et al. (författare) The dynamics of change in striatal activity following updating training 2013 Ingår i: Human Brain Mapping. - : Wiley. - 1065-9471 .- 1097-0193. ; 34:7, s. 1530-1541 Tidskriftsartikel (refereegranskat)abstract Increases in striatal activity have been suggested to mediate training-related improvements in working-memory ability. We investigated the temporal dynamics of changes in task-related brain activity following training of working memory. Participants in an experimental group and an active control group, trained on easier tasks of a constant difficulty in shorter sessions than the experimental group, were measured before, after about 1 week, and after more than 50 days of training. In the experimental group an initial increase of working-memory related activity in the functionally defined right striatum and anatomically defined right and left putamen was followed by decreases, resulting in an inverted u-shape function that relates activity to training over time. Activity increases in the striatum developed slower in the active control group, observed at the second posttest after more than 50 days of training. In the functionally defined left striatum, initial activity increases were maintained after more extensive training and the pattern was similar for the two groups. These results shed new light on the relation between activity in the striatum (especially the putamen) and the effects of working memory training, and illustrate the importance of multiple measurements for interpreting effects of training on regional brain activity.
14.	Kuhn, Simone, et al. (författare) The neural representation of intrusive thoughts 2013 Ingår i: Social Cognitive and Affective Neuroscience. - : Oxford University Press (OUP). - 1749-5024 .- 1749-5016. ; 8:6, s. 688-693 Tidskriftsartikel (refereegranskat)abstract Based on the philosophical notion that language embodies thought we investigated whether a habitual tendency for intrusive thought that younger and older participants report over a period of 100 sessions, spread out over about 6 months, is associated with brain regions related to language production. In favour of this hypothesis, we found that individual differences in habitual intrusive thoughts are correlated with activity in the left inferior frontal gyrus (IFG, Broca's area) as well as the cingulate cortex (CC) during a two-choice reaction-time task in fMRI. Participants who habitually tended to experience intrusive thoughts showed greater activity during task-free (baseline) compared to task periods in brain regions involved in language production. Task performance was unrelated to individual differences in intrusive thoughts. We conclude that intrusive thoughts may be represented in a language-like format and that individuals reporting a habitually higher tendency for intrusive thoughts may have stronger and more habitual inner speech processes.
15.	Lövdén, Martin, et al. (författare) A theoretical framework for the study of adult cognitive plasticity 2010 Ingår i: Psychological Bulletin. - : American Psychological Association (APA). - 1939-1455 .- 0033-2909. ; 136:4, s. 659-676 Tidskriftsartikel (refereegranskat)abstract Does plasticity contribute to adult cognitive development, and if so, in what ways? The vague and overused concept of plasticity makes these controversial questions difficult to answer. In this article, we refine the notion of adult cognitive plasticity and sharpen its conceptual distinctiveness. According to our framework, adult cognitive plasticity is driven by a prolonged mismatch between functional organismic supplies and environmental demands and denotes the brain's capacity for anatomically implementing reactive changes in behavioral flexibility (i.e., the possible range of performance and function). We distinguish between 2 interconnected but distinct cognitive outcomes of adult cognitive plasticity: alterations in processing efficiency and alterations in representations. We demonstrate the usefulness of our framework in evaluating and interpreting (a) increments in frontal brain activations in the course of normal aging and (b) the effects of cognitive training in adulthood and old age. Finally, we outline new research questions and predictions generated by the present framework and recommend design features for future cognitive-training studies.
16.	Lövdén, Martin, et al. (författare) Does variability in cognitive performance correlate with frontal brain volume? 2013 Ingår i: NeuroImage. - : Elsevier BV. - 1053-8119 .- 1095-9572. ; 64, s. 209-15 Tidskriftsartikel (refereegranskat)abstract Little is known about the neural correlates of within-person variability in cognitive performance. We investigated associations between regional brain volumes and trial-to-trial, block-to-block, and day-to-day variability in choice-reaction time, and episodic and working memory accuracy. Healthy younger (n=25) and older (n=18) adults underwent 101 daily assessments of cognitive performance, and their regional brain volumes were measured manually on magnetic resonance images. Results showed that smaller prefrontal white matter volumes were associated with higher block-to-block variability in choice-reaction time performance, with a stronger association observed among older adults. Smaller volumes of the dorsolateral prefrontal cortex covaried with higher block-to-block variability in episodic memory (number-word pair) performance. This association was stronger for younger adults. The observed associations between variability and brain volume were not due to individual differences in mean performance. Trial-to-trial and day-to-day variability in cognitive performance were unrelated to regional brain volume. We thus report novel findings demonstrating that block-by-block variability in cognitive performance is associated with integrity of the prefrontal regions and that between-person differences in different measures of variability of cognitive performance reflect different age-related constellations of behavioral and neural antecedents.
17.	Lövdén, Martin, et al. (författare) Experience-dependent plasticity of white-matter microstructure extends into old age 2010 Ingår i: Neuropsychologia. - : Elsevier BV. - 0028-3932 .- 1873-3514. ; 48:13, s. 3878-3883 Tidskriftsartikel (refereegranskat)abstract Experience-dependent alterations in the human brain's white-matter microstructure occur in early adulthood, but it is unknown whether such plasticity extends throughout life. We used cognitive training, diffusion-tensor imaging (DTI), and structural MRI to investigate plasticity of the white-matter tracts that connect the left and right hemisphere of the frontal lobes. Over a period of about 180 days, 20 younger adults and 12 older adults trained for a total of one hundred and one 1-h sessions on a set of three working memory, three episodic memory, and six perceptual speed tasks. Control groups were assessed at pre- and post-test. Training affected several DTI metrics and increased the area of the anterior part of the corpus callosum. These alterations were of similar magnitude in younger and older adults. The findings indicate that experience-dependent plasticity of white-matter microstructure extends into old age and that disruptions of structural interhemispheric connectivity in old age, which are pronounced in aging, are modifiable by experience and amenable to treatment.
18.	Noack, Hannes, et al. (författare) Age-Related Differences in Temporal and Spatial Dimensions of Episodic Memory Performance Before and After Hundred Days of Practice 2013 Ingår i: Psychology and Aging. - : American Psychological Association (APA). - 0882-7974 .- 1939-1498. ; 28:2, s. 467-480 Tidskriftsartikel (refereegranskat)abstract Normal aging impairs the representation and integration (binding) of spatial and temporal context in episodic memory. We directly compare age differences in episodic memory in relation to processing spatial and temporal context. As part of the COGITO study, 101 younger and 103 older participants trained an object-location serial recall task for 100 sessions. Training exacerbated the recall deficit of older relative to younger adults. Younger adults improved in recall performance on both spatial and temporal dimensions. In contrast, older adults improved on the spatial dimension only. Individual differences in pretest performance and change were positively correlated across dimensions among younger adults but negatively related among older adults. We conclude that older adults are impaired at simultaneously processing spatial and temporal context and preferentially process spatial at the expense of temporal context.
19.	Noack, Hannes, et al. (författare) Cognitive plasticity in adulthood and old age: Gauging the generality of cognitive intervention effects 2009 Ingår i: Restorative Neurology and Neuroscience. - 1878-3627. ; 27:5, s. 435-453 Forskningsöversikt (refereegranskat)abstract Interventions enabling aging individuals to fulfill their plastic potential promise to postpone, attenuate, or even reverse the adverse effects of senescent brain changes on cognitive abilities and everyday competence in old age. Based on an overview of the concept of plasticity in lifespan development, we selectively review evidence from cognitive intervention studies and conclude that most of them have failed to observe generalizable performance improvements, as documented by the small size and scope of positive transfer to untrained tasks. We further note that generally accepted criteria for defining transfer distance are lacking, rendering the relevant evidence difficult to interpret. Hence, we propose a taxonomy of transfer distance based on the structure of human intellectual abilities.
20.	Noack, Hannes, et al. (författare) On the validity and generality of transfer effects in cognitive training research 2014 Ingår i: Psychological Research. - : Springer Science and Business Media LLC. - 0340-0727 .- 1430-2772. ; 78:6, s. 773-789 Forskningsöversikt (refereegranskat)abstract Evaluation of training effectiveness is a long-standing problem of cognitive intervention research. The interpretation of transfer effects needs to meet two criteria, generality and specificity. We introduce each of the two, and suggest ways of implementing them. First, the scope of the construct of interest (e.g., working memory) defines the expected generality of transfer effects. Given that the constructs of interest are typically defined at the latent level, data analysis should also be conducted at the latent level. Second, transfer should be restricted to measures that are theoretically related to the trained construct. Hence, the construct of interest also determines the specificity of expected training effects; to test for specificity, study designs should aim at convergent and discriminant validity. We evaluate the recent cognitive training literature in relation to both criteria. We conclude that most studies do not use latent factors for transfer assessment, and do not test for convergent and discriminant validity.
21.	Raz, Naftali, et al. (författare) Differential brain shrinkage over 6 months shows limited association with cognitive practice 2013 Ingår i: Brain and Cognition. - : Elsevier BV. - 0278-2626 .- 1090-2147. ; 82:2, s. 171-180 Tidskriftsartikel (refereegranskat)abstract The brain shrinks with age, but the timing of this process and the extent of its malleability are unclear. We measured changes in regional brain volumes in younger (age 20-31) and older (age 65-80) adults twice over a 6 months period, and examined the association between changes in volume, history of hypertension, and cognitive training. Between two MRI scans, 49 participants underwent intensive practice in three cognitive domains for 100 consecutive days, whereas 23 control group members performed no laboratory cognitive tasks. Regional volumes of seven brain structures were measured manually and adjusted for intracranial volume. We observed significant mean shrinkage in the lateral prefrontal cortex, the hippocampus, the caudate nucleus, and the cerebellum, but no reliable mean change of the prefrontal white matter, orbital-frontal cortex, and the primary visual cortex. Individual differences in change were reliable in all regions. History of hypertension was associated with greater cerebellar shrinkage. The cerebellum was the only region in which significantly reduced shrinkage was apparent in the experimental group after completion of cognitive training. Thus, in healthy adults, differential brain shrinkage can be observed in a narrow time window, vascular risk may aggravate it, and intensive cognitive activity may have a limited effect on it.
22.	Schmiedek, Florian, et al. (författare) A task is a task is a task : putting complex span, n-back, and other working memory indicators in psychometric context 2014 Ingår i: Frontiers in Psychology. - : Frontiers Media SA. - 1664-1078. ; 5, s. 1475- Tidskriftsartikel (refereegranskat)abstract Based on a meta analysis, Redick and Lindsey 120131 found that complex span and n-back tasks show an average correlation of r = 0.20, and concluded that complex span and n-back tasks cannot be used interchangeably as working memory measures in research applications (p. 1102). Here, we comment on this conclusion from a psychometric perspective. In addition to construct variance, performance on a test contains measurement error, task specific variance, and paradigm specific variance. Hence, low correlations among dissimilar indicators do not provide strong evidence for the existence, or absence, of a construct common to both indicators. One way to arrive at such evidence is to fit hierarchical latent factors that model task-specific, paradigm-specific, and construct variance. We report analyses for 101 younger and 103 older adults who worked on nine different working memory tasks. The data are consistent with a hierarchical model of working memory, according to which both complex span and n-back tasks are valid indicators of working memory. The working memory factor predicts 71% of the variance in a factor of reasoning among younger adults (83% for among older adults). When the working memory factor was restricted to any possible triplet of working memory tasks, the correlation between working memory and reasoning was inversely related to the average magnitude of the correlations among the indicators, indicating that more highly intercorrelated indicators may provide poorer coverage of the construct space. We stress the need to go beyond specific tasks and paradigms when studying higher order cognitive constructs, such as working memory.
23.	Schmiedek, Florian, et al. (författare) Complex Span Versus Updating Tasks of Working Memory: The Gap Is Not That Deep 2009 Ingår i: Journal of Experimental Psychology: Learning, Memory, and Cognition. - : American Psychological Association (APA). - 0278-7393 .- 1939-1285. ; 35:4, s. 1089-1096 Tidskriftsartikel (refereegranskat)abstract How to best measure working memory capacity is an issue of ongoing debate. Besides established complex span tasks, which combine short-term memory demands with generally unrelated secondary tasks, there exists a set of paradigms characterized by continuous and simultaneous updating of several items in working memory, such as the n-back, memory updating, or alpha span tasks. With a latent variable analysis (N = 96) based on content-heterogeneous operationalizations of both task families, the authors found a latent correlation between a complex span factor and an updating factor that was not statistically different from unity (r = .96). Moreover, both factors predicted fluid intelligence (reasoning) equally well. The authors conclude that updating tasks measure working memory equally well as complex span tasks. Processes involved in building, maintaining, and updating arbitrary bindings may constitute the common working memory ability underlying performance on reasoning, complex span, and updating tasks.
24.	Schmiedek, Florian, et al. (författare) Hundred Days of Cognitive Training Enhance Broad Cognitive Abilities in Adulthood : Findings from the COGITO Study 2010 Ingår i: Frontiers in Aging Neuroscience. - Lausanne : Frontiers Research Foundation. - 1663-4365. ; 2, s. 1-10 Tidskriftsartikel (refereegranskat)abstract We examined whether positive transfer of cognitive training, which so far has been observed for individual tests only, also generalizes to cognitive abilities, thereby carrying greater promise for improving everyday intellectual competence in adulthood and old age. In the COGITO Study, 101 younger and 103 older adults practiced six tests of perceptual speed (PS), three tests of working memory (WM), and three tests of episodic memory (EM) for over 100 daily 1-h sessions. Transfer assessment included multiple tests of PS, WM, EM, and reasoning. In both age groups, reliable positive transfer was found not only for individual tests but also for cognitive abilities, represented as latent factors. Furthermore, the pattern of correlations between latent change factors of practiced and latent change factors of transfer tasks indicates systematic relations at the level of broad abilities, making the interpretation of effects as resulting from unspecific increases in motivation or self-concept less likely.
25.	Schmiedek, Florian, et al. (författare) Keeping It Steady. Older Adults Perform More Consistently on Cognitive Tasks Than Younger Adults 2013 Ingår i: Psychological Science. - : SAGE Publications. - 0956-7976 .- 1467-9280. ; 24:9, s. 1747-1754 Tidskriftsartikel (refereegranskat)abstract People often attribute poor performance to having bad days. Given that cognitive aging leads to lower average levels of performance and more moment-to-moment variability, one might expect that older adults should show greater day-to-day variability and be more likely to experience bad days than younger adults. However, both researchers and ordinary people typically sample only one performance per day for a given activity. Hence, the empirical basis for concluding that cognitive performance does substantially vary from day to day is inadequate. On the basis of data from 101 younger and 103 older adults who completed nine cognitive tasks in 100 daily sessions, we show that the contributions of systematic day-to-day variability to overall observed variability are reliable but small. Thus, the impression of good versus bad days is largely due to performance fluctuations at faster timescales. Despite having lower average levels of performance, older adults showed more consistent levels of performance across days.
26.	Schmiedek, Florian, et al. (författare) On the Relation of Mean Reaction Time and Intraindividual Reaction Time Variability 2009 Ingår i: Psychology and Aging. - : American Psychological Association (APA). - 0882-7974 .- 1939-1498. ; 24:4, s. 841-857 Tidskriftsartikel (refereegranskat)abstract Researchers often statistically control for means when examining individual or age-associated differences in variances, assuming that the relation between the 2 is linear and invariant within and across individuals and age groups. We tested this assumption in the domain of working memory by applying variance-heterogeneity multilevel models to reaction times in the n-back task. Data are from the COGITO study, which comprises 101 younger and 103 older adults assessed in over 100 daily sessions. We found that relations between means and variances vary reliably across age groups and individuals, thereby contradicting the invariant linearity assumption. We argue that statistical control approaches need to be replaced by theoretical models that simultaneously estimate central tendency and dispersion of latencies and accuracies and illustrate this claim by applying the diffusion model to the same data. Finally, we note that differences in reliability between estimates for means and variances need to be considered when comparing their unique contributions to developmental outcomes.
27.	Schmiedek, Florian, et al. (författare) Practice-Related Changes in Perceptual Evidence Accumulation Correlate With Changes in Working Memory 2023 Ingår i: Journal of Experimental Psychology: General. - : American Psychological Association (APA). - 0096-3445 .- 1939-2222. ; 152:3 Tidskriftsartikel (refereegranskat)abstract It has been proposed that evidence accumulation determines not only the speed and accuracy of simple perceptual decisions but also influences performance on tasks assessing higher-order cognitive abilities, such as working memory (WM). Accordingly, estimates of evidence accumulation based on diffusion decision modeling of perceptual decision-making tasks have been found to correlate with WM performance. Here we use diffusion decision modeling in combination with latent factor modeling to test the stronger prediction that practice-induced changes in evidence accumulation correlate with changes in WM performance. Analyses are based on data from the COGITO Study, in which 101 young adults practiced a battery of cognitive tasks, including three simple two-choice reaction time tasks and three WM tasks, in 100 day-to-day training sessions distributed over 6 months. In initial analyses, drift rates were found to correlate across the three choice tasks, such that latent factors of evidence accumulation could be established. These latent factors of evidence accumulation were positively correlated with latent factors of practiced and unpracticed WM tasks, both before and after practice. As predicted, individual differences in changes of evidence accumulation correlated positively with changes in WM performance. Our findings support the proposition that decision making and WM both rely on the active maintenance of task-relevant internal representations
28.	Schmiedek, Florian, et al. (författare) Within-person structures of daily cognitive performance differ from between-person structures of cognitive abilities 2020 Ingår i: PeerJ. - : PeerJ. - 2167-8359. ; 8 Tidskriftsartikel (refereegranskat)abstract Over a century of research on between-person differences has resulted in the consensus that human cognitive abilities are hierarchically organized, with a general factor, termed general intelligence or g, uppermost. Surprisingly, it is unknown whether this body of evidence is informative about how cognition is structured within individuals. Using data from 101 young adults performing nine cognitive tasks on 100 occasions distributed over six months, we find that the structures of individuals' cognitive abilities vary among each other, and deviate greatly from the modal between-person structure. Working memory contributes the largest share of common variance to both between- and within-person structures, but the g factor is much less prominent within than between persons. We conclude that between-person structures of cognitive abilities cannot serve as a surrogate for within-person structures. To reveal the development and organization of human intelligence, individuals need to be studied over time.
29.	Schmiedek, Florian, et al. (författare) Younger Adults Show Long-Term Effects of Cognitive Training on Broad Cognitive Abilities Over 2 Years 2014 Ingår i: Developmental Psychology. - : American Psychological Association (APA). - 0012-1649 .- 1939-0599. ; 50:9, s. 2304-2310 Tidskriftsartikel (refereegranskat)abstract In the COGITO study (Schmiedek, Lovden, & Lindenberger, 2010), 101 younger adults practiced 12 tests of perceptual speed, working memory, and episodic memory for over 100 daily 1-hr sessions. The intervention resulted in positive transfer to broad cognitive abilities, including reasoning and episodic memory. Here, we examine whether these ability-based transfer effects are maintained over time. Two years after the end of the training, 80 participants returned for follow-up assessments of the comprehensive battery of transfer tasks. We found reliable positive long-term transfer effects for reasoning and episodic memory, controlling for retest effects by including participants from the original control group. This shows, for the first time, that intensive cognitive training interventions can have long-term broad transfer at the level of cognitive abilities.
30.	Shing, Yee Lee, et al. (författare) Memory Updating Practice Across 100 Days in the COGITO Study 2012 Ingår i: Psychology and Aging. - : American Psychological Association (APA). - 0882-7974 .- 1939-1498. ; 27:2, s. 451-461 Tidskriftsartikel (refereegranskat)abstract We investigated working memory updating performance in younger and older adults before, during. and after 100-day practice. Performance to presentation time (PT) relation was fitted to a negatively accelerated logistic function. Relative to younger adults, older adults showed lower asymptotes at pretest and posttest, and shallower slopes at pretest. Older adults practicing the task with fast PT gained less than older adults practicing the task with slow PT, probably reflecting the persistent use of a selective strategy throughout the 100-day practice period in the fast FT group. These results have implications for designing and evaluating age-comparative working memory training programs.
31.	Werkle-Bergner, Markus, et al. (författare) Coordinated within-Trial Dynamics of Low-Frequency Neural Rhythms Controls Evidence Accumulation 2014 Ingår i: Journal of Neuroscience. - 0270-6474 .- 1529-2401. ; 34:25, s. 8519-8528 Tidskriftsartikel (refereegranskat)abstract Higher cognitive functions, such as human perceptual decision making, require information processing and transmission across widespread cortical networks. Temporally synchronized neural firing patterns are advantageous for efficiently representing and transmitting information within and between assemblies. Computational, empirical, and conceptual considerations all lead to the expectation that the informational redundancy of neural firing rates is positively related to their synchronization. Recent theorizing and initial evidence also suggest that the coding of stimulus characteristics and their integration with behavioral goal states require neural interactions across a hierarchy of timescales. However, most studies thus have focused on neural activity in a single frequency range or on a restricted set of brain regions. Here we provide evidence for cooperative spatiotemporal dynamics of slow and fast EEG signals during perceptual decision making at the single-trial level. Participants performed three masked two-choice decision tasks, one each with numerical, verbal, or figural content. Decrements in posterior alpha power (8 - 14 Hz) were paralleled by increments in high-frequency (>30 Hz) signal entropy in trials demanding active sensory processing. Simultaneously, frontocentral theta power (4 - 7 Hz) increased, indicating evidence integration. The coordinated alpha/theta dynamics were tightly linked to decision speed and remarkably similar across tasks, suggesting a domain-general mechanism. In sum, we demonstrate an inverse association between decision-related changes in widespread low-frequency power and local high-frequency entropy. The cooperation among mechanisms captured by these changes enhances the informational density of neural response patterns and qualifies as a neural coding system in the service of perceptual decision making.
32.	Wolff, Julia K., et al. (författare) Health Is Health Is Health? Age Differences in Intraindividual Variability and in Within-Person Versus Between-Person Factor Structures of Self-Reported Health Complaints 2012 Ingår i: Psychology and Aging. - : American Psychological Association (APA). - 0882-7974 .- 1939-1498. ; 27:4, s. 881-891 Tidskriftsartikel (refereegranskat)abstract The variability of health complaints within individuals across time has rarely been studied, and the question whether between- and within-person factor structures of health-related variables are equivalent has not been tested so far. We examined self-reported health complaints in 101 younger (20-31 years) and 103 older adults (65-80 years) over a period of 100 daily assessments. Data were analyzed with confirmatory two-level factor analysis. One-factor structures of health complaints provided an acceptable fit at the between- and average within-person levels in both age groups, supporting the assumption of equivalent average within- and between-person factor structures for health complaints. Age differences in loading patterns indicated that subjective health may be experienced differently by younger and older adults. Small age differences in mean levels of health symptoms were observed. Intraindividual variability in health complaints was reliable. Older adults fluctuated less from day to day than younger adults, presumably reflecting less fluctuation in objective health, differences in response styles, situational influences, or habituation processes. We conclude that future research should consider intraindividual variability as being descriptive of a person's health status, and take possible differences between within-and between-person factor structures of subjective health into account.

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