Binding and strategic selection in working memory: A lifespan dissociation.

Working memory (WM) shows a gradual increase during childhood, followed by accelerating decline from adulthood to old age. To examine these lifespan differences more closely, we asked 34 children (10–12 years), 40 younger adults (20–25 years), and 39 older adults (70–75 years) to perform a color change detection task. Load levels and encoding durations were varied for displays including targets only (Experiment 1) or targets plus distracters (Experiment 2, investigating a subsample of Experiment 1). WM performance was lower in older adults and children than in younger adults. Longer presentation times were associated with better performance in all age groups, presumably reflecting increasing effects of strategic selection mechanisms on WM performance. Children outperformed older adults when encoding times were short, and distracter effects were larger in children and older adults than in younger adults. We conclude that strategic selection in WM develops more slowly during childhood than basic binding operations, presumably reflecting the delay in maturation of frontal versus medio-temporal brain networks. In old age, both sets of mechanisms decline, reflecting senescent change in both networks. We discuss similarities to episodic memory development and address open questions for future research. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

News of cognitive cure for age-related brain shrinkage is premature: A comment on Burgmans et al. (2009).

The extant longitudinal literature consistently supports the notion of age-related declines in human brain volume. In a report on a longitudinal cognitive follow-up with cross-sectional brain measurements, Burgmans and colleagues (2009) claim that the extant studies overestimate brain volume declines, presumably due to inclusion of participants with preclinical cognitive pathology. Moreover, the authors of the article assert that such declines are absent among optimally healthy adults who maintain cognitive stability for several years. In this comment accompanied by reanalysis of previously published data, we argue that these claims are incorrect on logical, methodological, and empirical grounds. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Where people live and die makes a difference: Individual and geographic disparities in well-being progression at the end of life.

Life-span psychological research has long been interested in the contextual embeddedness of individual development. To examine whether and how regional variables relate to between-person disparities in the progression of late-life well-being, we applied three-level growth curve models to 24-year longitudinal data from deceased participants of the German Socio-Economic Panel Study (N = 3,427; age at death = 18 to 101 years). Results indicated steep declines in well-being with impending death, with some 8% of the between-person differences in both level and decline of well-being reflecting between-county differences. Exploratory analyses revealed that individuals living and dying in less affluent counties reported lower late-life well-being, controlling for key individual predictors, including age at death, gender, education, and household income. The regional variables examined did not directly relate to well-being change but were found to moderate (e.g., amplify) the disparities in change attributed to individual variables. Our results suggest that resource-poor counties provide relatively less fertile grounds for successful aging until the end of life and may serve to exacerbate disparities. We conclude that examinations of how individual and residential characteristics interact can further our understanding of individual psychological outcomes and suggest routes for future inquiry. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Memory plasticity across the life span: Uncovering children's latent potential.

Memory plasticity, or the ability to improve one's memory performance through instruction and training, is known to decline during adulthood. However, direct comparisons among middle childhood, adulthood, and old age are lacking. The authors examined memory plasticity in an age-comparative multisession training study. One hundred and eight participants ages 9-10, 11-12, 20-25, and 65-78 years learned and practiced an imagery-based mnemonic technique to encode and retrieve words by location cues. Individuals of all ages were able to acquire and optimize use of the technique. Older adults and children showed similar baseline performance and improvement through mnemonic instruction. However, in line with tenets from life-span psychology (P. B. Baltes, 1987), children profited more from mnemonic practice and reached higher levels of final performance than did older adults. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Causality, agency, and control beliefs in East versus West Berlin children: A natural experiment on the role of context.

Beliefs about factors that affect school performance (means-ends or causality beliefs) and about self-efficacy and control (agency and control beliefs) were assessed in 313 East Berlin children before unification and in 516 West Berlin children (all in Grades 2–6) shortly after unification. Multiple-group analyses of mean and covariance structures yielded 2 major differences: (1) East Berlin Ss showed lower agency and control beliefs than West Berlin Ss and (2) their agency and control beliefs were more highly correlated with school grades than West Berlin Ss', with strong correlations already emerging in East Berlin 2nd graders. Findings were consistent with differences between East and West Berlin school systems. East Berlin regulations emphasized public performance feedback and public self-evaluation and enforced unidimensional teaching strategies. Results point to a risk factor for development in East Berlin children. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Grafting polythiophene on polyethylene surfaces

Polythiophene (PT) was grafted on PE film using three reaction steps. First, PE films were brominated in the gas phase, yielding PE–Br; second, a substitution reaction of PE–Br with 2‐thiophene thiolate anion gave the thiophene‐functionalized PE; finally PT was grafted on the PE surface using chemical oxidative polymerization to give PE–PT. The polymerization was carried out in a suspension solution of anhydrous FeCl₃ in CHCl₃, yielding a reddish PE–PT film after dedoping with ethanol. ATR‐FTIR shows that the PT was grafted on PE in the 2,5‐position. SEM imaging revealed islands of PT on the PE film. AFM analysis found the thickness of islands to be in the range of 120–145 nm. The conductivity of these thin films was in the range of 10^?6 S cm^?1, a significant increase from the value of ～10^?14 S cm^?1 measured for PE film. © 2003 Society of Chemical Industry     

Sensory functioning and intelligence in old age: A strong connection.

Relations among age, sensory functioning (i.e., visual and auditory acuity), and intelligence were examined in a heterogeneous, age-stratified sample of old and very old individuals (N?=?156, M age?=?84.9 yrs, age range?=?70–203). Intelligence was assessed with 14 tests measuring 5 cognitive abilities (speed, reasoning, memory, knowledge, and fluency). Together, visual and auditory acuity accounted for 49.2% of the total and 93.1% of the age-related reliable variance in intelligence. The data were consistent with structural models in which age differences in intelligence, including speed, are completely mediated by differences in vision and hearing. Results suggest that sensory functioning is a strong late-life predictor of individual differences in intellectual functioning. Explanations are discussed, including the possibility that visual and sensory acuity are indicators of the physiological integrity of the aging brain (common cause hypothesis). (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Age differences between children and young adults in the dynamics of dual-task prioritization: Body (balance) versus mind (memory).

Task prioritization can lead to trade-off patterns in dual-task situations. The authors compared dual-task performances in 9- and 11-year-old children and young adults performing a cognitive task and a motor task concurrently. The motor task required balancing on an ankle-disc board. Two cognitive tasks measured working memory and episodic memory at difficulty levels individually adjusted during the course of extensive training. Adults showed performance decrements in both task domains under dual-task conditions. In contrast, children showed decrements only in the cognitive tasks but actually swayed less under dual-task than under single-task conditions and continued to reduce their body sway even when instructed to focus on the cognitive task. The authors argue that children perform closer to their stability boundaries in the balance task and therefore prioritize protection of their balance under dual-task conditions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

On selecting indicators for multivariate measurement and modeling with latent variables: When "good" indicators are bad and "bad" indicators are good.

Selecting indicators is as important for the generalizability of research designs as selecting persons or occasions of measurement. Elaborating on the extant knowledge base regarding indicator selection, the authors examine selection influences on the validity and reliability of multivariate representations. A simulation that systematically varied 4 key dimensions of indicator selection was used to investigate their effects on the fidelity of construct representations and the relative ability of exploratory and confirmatory analyses to recover within- and between-construct information. Confirmatory analyses, for example, yielded valid and unbiased estimates of the relations between constructs, even under conditions of very low internal consistency. Design, procedural, and analysis recommendations based on an expanded taxonomy of indicator selection and the simulation results are provided. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Biopolymer system for cell recovery from microfluidic cell capture devices

Microfluidic systems for affinity-based cell isolation have emerged as a promising approach for the isolation of specific cells from complex matrices (i.e., circulating tumor cells in whole blood). However, these technologies remain limited by the lack of reliable methods for the innocuous recovery of surface captured cells. Here, we present a biofunctional sacrificial hydrogel coating for microfluidic chips that enables the highly efficient release of isolated cells (99% ± 1%) following gel dissolution. This covalently cross-linked alginate biopolymer system is stable in a wide variety of physiologic solutions (including EDTA treated whole blood) and may be rapidly degraded via backbone cleavage with alginate lyase. The capture and release of EpCAM expressing cancer cells using this approach was found to have no significant effect on cell viability or proliferative potential, and recovered cells were demonstrated to be compatible with downstream immunostaining and FISH analysis.