The Effects of Nicotine on Attention and Working Memory in Never-Smokers.

The subjective and physiological effects of nicotine in nicotine-naive individuals are consistent across studies, though the cognitive effects are variable: Positive, negative, or no effects have been reported. Assessing specific cognitive processes (e.g., alerting, orienting, executive function, and phonological and visuospatial working memory) may help reduce this variability. This within-subject study (N = 20) was designed to assess the effect of nicotine gum (0, 2, or 4 mg) on subjective, physiological, and cognitive measures. Dose-dependent increases in dysphoria and heart rate were observed, though nicotine did not influence any aspect of attention or working memory. Future studies should take into account the difference in effect sizes for cognitive versus physiological/subjective measures and maximize power (e.g., increase sample size) accordingly. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Working memory training in older adults: Evidence of transfer and maintenance effects.

Few studies have examined working memory (WM) training-related gains and their transfer and maintenance effects in older adults. This present research investigates the efficacy of a verbal WM training program in adults aged 65–75 years, considering specific training gains on a verbal WM (criterion) task as well as transfer effects on measures of visuospatial WM, short-term memory, inhibition, processing speed, and fluid intelligence. Maintenance of training benefits was evaluated at 8-month follow-up. Trained older adults showed higher performance than did controls on the criterion task and maintained this benefit after 8 months. Substantial general transfer effects were found for the trained group, but not for the control one. Transfer maintenance gains were found at follow-up, but only for fluid intelligence and processing speed tasks. The results are discussed in terms of cognitive plasticity in older adults. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

On the law relating processing to storage in working memory.

Working memory is usually defined in cognitive psychology as a system devoted to the simultaneous processing and maintenance of information. However, although many models of working memory have been put forward during the last decades, they often leave underspecified the dynamic interplay between processing and storage. Moreover, the account of their interaction proposed by the most popular A. D. Baddeley and G. Hitch's (1974) multiple-component model is contradicted by facts, leaving unresolved one of the main issues of cognitive functioning. In this article, the author derive from the time-based resource-sharing model of working memory a mathematical function relating the cognitive load involved by concurrent processing to the amount of information that can be simultaneously maintained active in working memory. A meta-analysis from several experiments testing the effects of processing on storage corroborates the parameters of the predicted function, suggesting that it properly reflects the law relating the 2 functions of working memory. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Time and cognitive load in working memory.

According to the time-based resource-sharing model (P. Barrouillet, S. Bernardin, & V. Camos, 2004), the cognitive load a given task involves is a function of the proportion of time during which it captures attention, thus impeding other attention-demanding processes. Accordingly, the present study demonstrates that the disruptive effect on concurrent maintenance of memory retrievals and response selections increases with their duration. Moreover, the effect on recall performance of concurrent activities does not go beyond their duration insofar as the processes are attention demanding. Finally, these effects are not modality specific, as spatial processing was found to disrupt verbal maintenance. These results suggest a sequential and time-based function of working memory in which processing and storage rely on a single and general purpose attentional resource needed to run executive processes devoted to constructing, maintaining, and modifying ephemeral representations. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Spatial Working Memory Deficits in Children at Ages 3-4 Who Were Low Birth Weight, Preterm Infants.

The aim of this study was to investigate attention and perceptual and spatial working memory abilities in preterm, low birth weight preschool children without evident brain disorders as determined by normal cerebral ultrasound findings and normal motor development. The authors evaluated 19 preterm and 19 typically developing children who were matched for IQ and chronological age. Results indicated that children born prematurely without major neurological deficits and with a normal cognitive level may have specific difficulty in sustained attention, visuospatial processing, and spatial working memory when evaluated at ages 3-4. This finding is relevant for understanding the qualitative aspects of cognitive development in preterm children and the neurobiological substrate underlying this development. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Working Memory and Perseveration in Verbal Fluency.

Letter and semantic fluency tasks are often used in neuropsychological assessment and are sensitive to many conditions. Performance is assessed by correct responses and errors, including perseverations. Healthy young adults performed letter and semantic fluency tasks. One group performed these tasks in the conventional manner; 2 other groups performed them while maintaining memory loads. The memory loads consisted either of words from the same category as the fluency task or of words from a different category. The results showed little effect of memory loads on correct responses but significant effects of memory load on perseveration rates: Same-category loads resulted in higher rates, especially in letter fluency. The results are discussed in terms of frontal lobe function in verbal fluency. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A Working Memory Workout: How to Expand the Focus of Serial Attention From One to Four Items in 10 Hours or Less.

Five individuals participated in an extensive practice study (10 1-hr sessions, 11,000 trials total) on a self-paced identity-judgment n-back task (n ranging from 1 to 5). Within Session 1, response time increased abruptly by about 300 ms in passing from n = 1 to n > 1, suggesting that the focus of attention can accommodate only a single item (H. Caravan, 1998; B. McElree, 2001). Within Session 10, response time was dramatically reduced and increased linearly with n for n ≤ 4, with a slope of about 30 ms. The data suggest that working memory consists of a focus of attention governed by a limited-capacity search, expandable through practice, and a content-addressable region outside the focus of attention. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of Apolipoprotein E Genotype on Spatial Attention, Working Memory, and Their Interaction in Healthy, Middle-Aged Adults: Results From the National Institute of Mental Health's BIOCARD Study.

The cognitive consequences of the apolipoprotein E-ε4 (APOE-ε4) allele were examined in middle age, before likely onset of symptoms of Alzheimer's disease. The authors identified 3 cognitive processes--visuospatial attention, spatial working memory, and the effect of visuospatial attention on working memory--and devised "behavioral assays" of the integrity of components of these processes. Redirecting visuospatial attention, retention of memory for location, and attentional modulation of memory of target location were affected by APOE genotype. Visuospatial attention showed additive effects of ε4 gene dose; each additional ε4 allele inherited further slowed disengagement from invalidly cued space. In contrast, working memory performance was affected only in ε4 homozygotes. Effect sizes for the APOE gene were moderate to large, ranging from 14% to 24%. Effects of APOE genotype on component processes of cognition in healthy, middle-aged adults is consistent with the emergence in adulthood of an APOE-ε4 cognitive phenotype. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Working Memory, Task Switching, and Executive Control in the Task Span Procedure.

Four experiments explored the task span procedure: Subjects received lists of 1-10 task names to remember and then lists of 1-10 stimuli on which to perform the tasks. Task span is the number of tasks performed in order perfectly. Experiment 1 compared the task span with the traditional memory span in 6 practiced subjects and found little difference. Experiment 2 compared the task span and the memory span in 64 unpracticed subjects and also found little difference. Experiment 3 compared practice with consistent and varied lists to address retrieval from long-term memory. Experiment 4 manipulated the number of task switches and found that it had little effect on task spans. The results suggest there is no trade-off between storage and task switching, which supports some theories of executive control and challenges others. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Testing possible mechanisms of deficient supra-second time estimation in adults with attention-deficit/hyperactivity disorder.

Numerous studies indicate deficient time estimation in individuals with attention-deficit/hyperactivity disorder (ADHD). Several hypotheses have been raised to explain this deficit including delay aversion, vulnerability to nontemporal distractions, deficient working memory, as well as pure deficit in temporal processing. To test the different hypotheses, adults with or without ADHD performed a prospective time-estimation task under different conditions: with or without nontemporal distraction; and with or without increased load of working memory. Such design was used to rule out the effect of motor control and to manipulate the hypothesized mechanisms of working memory and attention to nontemporal stimuli. The authors report that compared with the control group, adults with ADHD showed greater and more variable deviation in time estimation. In addition, the magnitude of time estimation was affected by allocation of attention to nontemporal stimuli and by load of working memory. The intraindividual variability of time estimation was only partially accounted for by load of working memory. These findings suggest that the ADHD-associated deficit in prospective time estimation is not attributable to special attention to nontemporal stimuli or compromised working memory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Individual Differences in Working Memory Capacity and Dual-Process Theories of the Mind.

Dual-process theories of the mind are ubiquitous in psychology. A central principle of these theories is that behavior is determined by the interplay of automatic and controlled processing. In this article, the authors examine individual differences in the capacity to control attention as a major contributor to differences in working memory capacity (WMC). The authors discuss the enormous implications of this individual difference for a host of dual-process theories in social, personality, cognitive, and clinical psychology. In addition, the authors propose several new areas of investigation that derive directly from applying the concept of WMC to dual-process theories of the mind. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The Relationship Between Working Memory and Mathematical Problem Solving in Children at Risk and Not at Risk for Serious Math Difficulties.

This study identified cognitive processes that underlie individual differences in working memory (WM) and mathematical problem-solution accuracy in elementary school children at risk and not at risk for serious math difficulties (SMD). A battery of tests was administered that assessed problem solving, achievement, and cognitive processing in children in first (N = 130), second (N = 92) and third grades (N = 131). The results were that (a) younger children and children at risk for SMD performed poorer on WM and problem-solving tasks, as well as measures of math calculation, reading, semantic processing, phonological processing, and inhibition, than older children and children not at risk for SMD and (b) WM predicted solution accuracy of word problems independent of measures of fluid intelligence, reading skill, math skill, knowledge of algorithms, phonological processing, semantic processing,'speed, shortterm memory, and inhibition. The results support the notion that the executive system is an important predictor of children's problem solving. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Identification of Tone Duration, Line Length, and Letter Position: An Experimental Approach to Timing and Working Memory Deficits in Schizophrenia.

Patients with schizophrenia display numerous cognitive deficits, including problems in working memory, time estimation, and absolute identification of stimuli. Research in these fields has traditionally been conducted independently. We examined these cognitive processes using tasks that are structurally similar and that yield rich error data. Relative to healthy control participants (n = 20), patients with schizophrenia (n = 20) were impaired on a duration identification task and a probed-recall memory task but not on a line-length identification task. These findings do not support the notion of a global impairment in absolute identification in schizophrenia. However, the authors suggest that some aspect of temporal information processing is indeed disturbed in schizophrenia. (PsycINFO Database Record (c) 2010 APA, all rights reserved)