Aerobic fitness and cognitive development: Event-related brain potential and task performance indices of executive control in preadolescent children.

The relationship between aerobic fitness and executive control was assessed in 38 higher- and lower-fit children (Mage = 9.4 years), grouped according to their performance on a field test of aerobic capacity. Participants performed a flanker task requiring variable amounts of executive control while event-related brain potential responses and task performance were assessed. Results indicated that higher-fit children performed more accurately across conditions of the flanker task and following commission errors when compared to lower-fit children, whereas no group differences were observed for reaction time. Neuroelectric data indicated that P3 amplitude was larger for higher- compared to lower-fit children across conditions of the flanker task, and higher-fit children exhibited reduced error-related negativity amplitude and increased error positivity amplitude compared to lower-fit children. The data suggest that fitness is associated with better cognitive performance on an executive control task through increased cognitive control, resulting in greater allocation of attentional resources during stimulus encoding and a subsequent reduction in conflict during response selection. The findings differ from those observed in adult populations by indicating a general rather than a selective relationship between aerobic fitness and cognition. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Intraindividual Variability May Not Always Indicate Vulnerability in Elders' Cognitive Performance.

This study examined consistency of performance, or intraindividual variability, in older adults' performance on 3 measures of cognitive functioning: inductive reasoning, memory, and perceptual speed. Theoretical speculation has suggested that such intraindividual variability may signal underlying vulnerability or neurologic compromise. Thirty-six participants aged 60 and older completed self-administered cognitive assessments twice a day for 60 consecutive days. Intraindividual variability was not strongly correlated among the 3 cognitive measures, but, over the course of the study, intraindividual variability was strongly intercorrelated within a task. Higher average performance on a measure was associated with greater performance variability, and follow-up analyses revealed that a higher level of intraindividual variability is positively associated with the magnitude of a person's practice-related gain on a particular measure. The authors argue that both adaptive (practice-related) and maladaptive (inconsistency-related) intraindividual variability may exist within the same individuals over time. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Performance variability is related to change in cognition: Evidence from the Victoria Longitudinal Study.

Performance variability across repeated task administrations may be an important indicator of age-related cognitive functioning. In the present investigation, the authors examined whether age differences and change in inconsistency were related to 6-year (3 occasion) cognitive change. Inconsistency scores were computed from 4 reaction time tasks performed by 446 older adults (54-89 years). Replicating previous cross-sectional results, greater inconsistency was observed for older participants even after controlling for differences in response speed. New longitudinal results demonstrated (a) associations between inconsistency at baseline measurement and 6-year change in cognitive performance; (b) longitudinal change in inconsistency; and (c) intraindividual covariation between 6-year change in inconsistency and 6-year change in level of cognitive function. These findings support the view that performance variability serves as a marker of cognitive aging. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Intraindividual variability in cognitive performance in older adults: Comparison of adults with mild dementia, adults with arthritis, and healthy adults.

Intraindividual variability in latency and accuracy of cognitive performance across both trials and occasions was examined in 3 groups of older adults: healthy adults, adults with arthritis, and adults diagnosed with mild dementia. Participants completed 2 reaction-time and 2 episodic-memory tasks on 4 occasions. Results indicated that intraindividual variability in latency was greater in individuals diagnosed with mild dementia than in adults who were neurologically intact, regardless of their health status. Individual differences in variability were stable over time and across cognitive domains. Intraindividual variability was also related to level of performance and was uniquely predictive of neurological status, independent of level of performance. Results suggest that intraindividual variability may be a behavioral indicator of compromised neurological mechanisms. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Physical activity and cognitive function in a cross-section of younger and older community-dwelling individuals.

Previous reports have indicated a small, positive relationship between physical activity and cognition. However, the majority of research has focused on older adults, with few studies examining this relationship during earlier periods of the life span. This study examined the relationship of physical activity to cognition in a cross-section of 241 community-dwelling individuals 15-71 years of age with a task requiring variable amounts of executive control. Data were analyzed with multiple regression, which controlled for age, sex, and IQ. Participants reported their physical activity behavior and were tested for reaction time (RT) and response accuracy on congruent and incongruent conditions of a flanker task, which manipulates interference control. After controlling for confounding variables, an age-related slowing of RT was observed during both congruent and incongruent flanker conditions. However, physical activity was associated with faster RT during these conditions, regardless of age. Response accuracy findings indicated that increased physical activity was associated with better performance only during the incongruent condition for the older cohort. Findings suggest that physical activity may be beneficial to both general and selective aspects of cognition, particularly among older adults. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Intraindividual variability is related to cognitive change in older adults: Evidence for within-person coupling.

In this study, the authors addressed the longitudinal nature of intraindividual variability over 3 years. A sample of 304 community-dwelling older adults, initially between the ages of 64 and 92 years, completed 4 waves of annual testing on a battery of accuracy- and latency-based tests covering a wide range of cognitive complexity. Increases in response-time inconsistency on moderately and highly complex tasks were associated with increasing age, but there were significant individual differences in change across the entire sample. The time-varying covariation between cognition and inconsistency was significant across the 1-year intervals and remained stable across both time and age. On occasions when intraindividual variability was high, participants' cognitive performance was correspondingly low. The strength of the coupling relationship was greater for more fluid cognitive domains such as memory, reasoning, and processing speed than for more crystallized domains such as verbal ability. Variability based on moderately and highly complex tasks provided the strongest prediction. These results suggest that intraindividual variability is highly sensitive to even subtle changes in cognitive ability. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Intraindividual variability in reaction time predicts cognitive outcomes 5 years later.

Objective: Building on results suggesting that intraindividual variability in reaction time (inconsistency) is highly sensitive to even subtle changes in cognitive ability, this study addressed the capacity of inconsistency to predict change in cognitive status (i.e., cognitive impairment, no dementia [CIND] classification) and attrition 5 years later. Method: Two hundred twelve community-dwelling older adults, initially aged 64–92 years, remained in the study after 5 years. Inconsistency was calculated from baseline reaction time performance. Participants were assigned to groups on the basis of their fluctuations in CIND classification over time. Logistic and Cox regressions were used. Results: Baseline inconsistency significantly distinguished among those who remained or transitioned into CIND over the 5 years and those who were consistently intact (e.g., stable intact vs. stable CIND, Wald (1) = 7.91, p     

Physiological and perceptual responses during household activities performed by healthy women

OBJECTIVE: The purpose of this study was to describe the physiological and perceptual responses during two physically demanding household tasks: cleaning the bathroom and vacuuming the living room. It also examined the relationship between predicted aerobic fitness and the physiological responses during the two tasks. METHOD: Seventeen healthy women between 30 and 50 years of age volunteered as participants. They were interviewed to gather demographic information required for prediction of aerobic fitness and observed while performing each task for 17 min to 20 min in their own home. RESULTS: The heart rate, an index of circulatory strain, varied considerably among the participants and was moderately high during both tasks. Vacuuming the living room had a higher level of circulatory strain and perceived exertion than cleaning the bathroom. An inverse relationship existed between the predicted aerobic fitness and heart rate responses during the two tasks. CONCLUSION: Routine household tasks result in a significant circulatory strain in healthy women. Persons with high levels of aerobic fitness experience a lower degree of circulatory strain.     

Executive function in children with Tourette syndrome and/or attention deficit hyperactivity disorder

Tourette Syndrome (TS) in children is associated with various neurobehavioral disorders including attention deficit hyperactivity disorder (ADHD). Children with TS and ADHD show some difficulties with neuropsychological tasks, but we do not know if children with TS alone have neuropsychological deficits. To assess specific cognitive differences among children with TS and/or ADHD, we administered a battery of neuropsychological tests, including 10 tasks related to executive function (EF), to 10 children with TS-only, 48 with ADHD-only, and 32 with TS + ADHD. Children in all groups could not efficiently produce output on a timed continuous performance task [Test of Variables of Attention (TOVA) mean reaction time and reaction time variability]. Children with TS-only appeared to have fewer EF impairments and significantly higher perceptual organization scores than children with TS + ADHD or ADHD-only. These findings suggest that deficiencies in choice reaction time and consistency of timed responses are common to all three groups, but children with TS-only have relatively less EF impairment than children with TS + ADHD or ADHD-only.     

Delta Plots in the Study of Individual Differences: New Tools Reveal Response Inhibition Deficits in AD/HD That Are Eliminated by Methylphenidate Treatment.

The authors highlight the utility of distribution-analytical techniques in the study of individual differences and clinical disorders. Cognitive deficits associated with attention-deficit/hyperactivity disorder (AD/HD) were examined by using delta-plot analyses of performance data (reaction time and accuracy) obtained through the use of a prototypical conflict task, the Eriksen flanker task. In 20 children with AD/HD (compared with matched control participants), overall performance measures indicated a marginal performance deficit. Delta-plot analyses indicated that performance deficits associated with AD/HD involve response inhibition but not automatic response activation. In a within-subjects titration study, the response inhibition deficit was eliminated by methylphenidate treatment, but these effects were highly dose specific. The beneficial effect of methylphenidate was clarified further after correcting for inter-individual variation in sensitivity to medicine dosage. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Evidence for selective inhibitory impairment in individuals with autism spectrum disorder.

Objective: The social and communicative challenges faced by individuals with autism spectrum disorder (ASD) are often compounded by additional difficulties with executive function. It remains unclear, however, to what the extent individuals with ASD experienced impairment in inhibitory control. The objective of the present study was to assess the three main subtypes of executive inhibitory control within a single ASD sample thus providing new insight into the unique ASD-related pattern of sparing and impairment observed across different aspects of inhibitory control. Method: A sample of 28 children with ASD (mean age = 13.1 years) and a comparison group of 49 neurologically uncompromised children (mean age = 13.3 years) participated. A prepotent response inhibition task, a flanker visual filtering task, and a proactive interference memory task were used to evaluate prepotent response inhibition, resistance to distracter interference, and resistance to proactive interference, respectively. Results: After accounting for individual differences in noninhibition abilities (e.g., processing speed) and overall level of functioning, there was no evidence of group-related differences in inhibitory performance on the prepotent response inhibition test or proactive interference test. ASD-related impairments in inhibitory control were evident, however, on the flanker visual filtering task. Conclusions: Taken together, the present findings indicate that ASD is associated with impairments in some, but not all, aspects of inhibitory control. Individuals with ASD appear to have difficulty ignoring distracting visual information, but prepotent response inhibition and resistance to proactive interference are relatively intact. The current findings also provide support for a multitype model of inhibitory control. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Across-task conflict regulation: A replication failure.

Fernandez-Duque and Knight (2008, Experiment 4) described an across-task effect of endogenously generated, anticipatory control: A cue that predicted conflict in an upcoming Eriksen flanker task modulated conflict regulation in a subsequent number Stroop task. In 3 experiments, 1 of which included an exact replication condition, we failed to observe the expected across-task effect. However, a reanalysis of our data revealed a conflict adaptation effect: Number task processing on incongruent trials was influenced by random fluctuations in flanker task performance. Our findings, alongside reports of reactive across-task conflict regulation (Freitas, Bahar, Yang, & Banai, 2007), challenge Fernandez-Duque and Knight’s claim that across-task effects are a distinctive feature of anticipatory cognitive control. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Aerobic fitness and psychophysiological reactivity.

Examined the pattern of psychophysiological response to a demanding cognitive task in 10 males and 9 females (aged 35–45 yrs) of different aerobic fitness levels. Following baseline measures of heart rate and skin conductance, Ss performed a task with cognitive, motor, visual, and auditory components that caused an information processing system overload argued to be psychologically stressful. Aerobic fitness level was correlated with psychophysiological reactivity during and following exposure to the task. Fitness level was unrelated to heart rate and skin conductance level during the task but was positively correlated with speed of recovery to baseline once the task terminated. Within individual Ss, the 2 psychophysiological indices followed different time courses during recovery, but the rates of recovery were positively correlated. The quicker psychophysiological recovery of the aerobically fitter Ss may mediate certain psychological adaptations associated with improved physical fitness. (7 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Cardiac and respiratory responses during visual search in nonretarded children and retarded adolescents

The relationship between physiological response patterns and mental competence was investigated by evaluating heart rate and respiratory responses during a sustained visual-search task in nonretarded grade school children and retarded adolescents. The findings support the contention that, during tasks demanding sustained attention, retarded relative to nonretarded individuals exhibit physiological responses that parallel their poor performance. Consistent with previous research with nonretarded adults, the nonretarded grade school children exhibited a suppression of respiratory and heart-rate variability during attention-demanding tasks. In contrast, the retarded adolescents exhibited increases in respiratory and heart-rate variability. These qualitative differences in physiological and behavioral responses, observed during sustained attention, may be viewed as a manifestation of retarded adolescents' defective nervous system.     

Does response variability predict distractibility among adults with attention-deficit/hyperactivity disorder?

Increased intraindividual variability in response time (RTSD) has been observed reliably in attention-deficit/hyperactivity disorder (ADHD) and has often been used as a measure of inattention. RTSD is assumed to reflect attentional lapses and distractibility, though evidence for the validity of this connection is lacking. We assessed whether RTSD is an indicator of inattention by comparing RTSD on the stop-signal task (SST) with performance on the delayed oculomotor response (DOR) task, a measure of distractibility. Participants included 30 adults with ADHD and 28 controls. Participants completed the SST and the DOR task, which measured subjects' ability to maintain attention and avoid distraction by inhibiting reflexive saccades toward distractors. On the SST, the ADHD group was slower to inhibit than were controls, indicating poorer inhibitory control in ADHD. The ADHD group also displayed slower reaction times (RTs), greater RTSD, and more omission errors. On the DOR task, the ADHD group displayed more premature saccades (i.e., greater distractibility) than did controls. Greater variability in RT was associated with increased distraction on the DOR task, but only in ADHD participants. Results suggest that RTSD is linked to distractibility among adults with ADHD and support the use of RTSD as a valid measure of inattention in ADHD. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Behavior problem trajectories and first-grade cognitive ability and achievement skills: A latent growth curve analysis.

Using data from the National Institute of Child Health and Human Development Study of Early Child Care and Youth Development, the authors investigated whether there was evidence of intraindividual stability in behavior problems over time as well as whether children with higher levels of behavior problems at 24 months and more rapid increases in behavior problems prior to school entry performed more poorly on 1st-grade tests of cognitive ability and achievement than their peers. Three findings were noteworthy. First, there was evidence of both intraindividual and interindividual variability in behavior problems between 24 months and 1st grade. Second, children with higher initial levels of internalizing and externalizing behaviors at 24 months had lower cognitive ability and achievement scores in 1st grade. Finally, children with more rapid increases in internalizing behaviors over time had lower cognitive ability scores in 1st grade; this association did not exist for externalizing behaviors. Implications for future research are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Concussion does not impact intraindividual response time variability.

This investigation examined the effect of concussion on intraindividual variability in 5 processing speed tasks. Forty-four adults, including 22 concussed and 22 healthy age- and gender-matched participants, completed the Headminder Concussion Resolution Index (D. M. Erlanger, D. J. Feldman, K. C. Kutner,& M. McCrea, 2001) twice. The test consists of a series of tasks including 25 trials of simple response time task, 70 trials of cued response time task (CuRT), 60 trials each for 2 visual recognition tasks, and 30 trials of symbol scanning task. Concussed participants completed a preinjury baseline assessment and were retested within 48 hours of injury diagnosis. The nonconcussed participants were retested 45 days after initial assessment. Average response time (RT), standard deviation, and response accuracy were calculated for each individual. Overall, concussed individuals had increased RTs across all tasks and were less accurate in the CuRT. RT variability for all tasks was elevated in concussed individuals, but controlling for mean RT at follow-up eliminated group differences. These findings indicate that response-time-variability increases in concussed individuals are proportional to processing-time increases. As such, RT variability is not a unique identifier of cognitive dysfunction following concussion. These results highlight that transient brain injury has significantly different neurobiological consequences than chronic conditions have. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Personality conflict, originality of response, and recall.

The general hypothesis states that variability in response to the same repeated stimulus is a function of intraindividual conflict. Applying this formulation to personality conflict, it is expected that the conflicted individual will show greater variability as a function of competing responses which appear alternately in subsequent similar situations. A measure of approach-avoidance personality conflict is described. High and low scorers on this conflict scale were exposed to a word-association task and were then required to recall their own responses. On the basis of the competing-tendency hypothesis, it was predicted that the conflicted subjects would show a higher frequency of original responses and reduced efficiency of recall. Both predictions were confirmed. Four instructional conditions preceding the word-association task failed to affect the conflict groups differentially, but personality and achievement instructions resulted in higher recall for both conflict groups. Some suggestions are offered for an improved measure of personality conflict. The results are discussed in terms of the conflict-variability hypothesis, and some implications are drawn for research on creativity. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Comparative effects of different test day challenges on performance in the 5-choice serial reaction time task.

The 5-choice serial reaction time task (5-CSRTT) is a valuable cognitive test that permits the simultaneous assessment of several different cognitive modalities, including attention, impulse control, processing speed, and cognitive flexibility. Increasing task difficulty on test days through various challenges can further enhance the versatility of this test by selectively enhancing the cognitive load on different aspects of the task. Systematic comparisons of the effects of different test day challenges on 5-CSRTT performance are essential to verify how these challenges affect different task measures and which manipulations are best suited for future studies of different aspects of cognition. We trained Wistar rats in the 5-CSRTT under standard conditions, then challenged them on the test days by (1) decreasing the duration of the stimulus to be detected, (2) increasing the time interval between trials (intertrial interval, ITI), (3) randomly varying the ITI, or (4) adding a flashing light distractor. All test day challenges produced distinct profiles of performance disruption that reflected differential effects on different cognitive modalities. Decreased stimulus duration selectively impaired attentional performance, while increased ITI increased impulsive-like premature responses and decreased trials completed. Variable ITI induced only mild, nonsignificant disruptions in response inhibition and processing speed, while the flashing light distractor produced comprehensive impairment affecting multiple aspects of 5-CSRTT performance, including disrupted attention and increased premature and timeout responses. This improved understanding of the effects of different test day challenges in the 5-CSRTT will allow researchers to use these manipulations of a valuable cognitive test to their full potential. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Effects of aerobic exercise training, age, and physical fitness on memory-search performance.

We investigated the effects of exercise training on memory performance. One group of 13 men (M?=?42.92 years of age) participated in supervised aerobic exercise (jogging) three times a week for 12 weeks. A second group of 15 men (M?=?43.67 years of age) performed anaerobic exercise (strength training) for the same period of time. Subjects' reaction time (RT) performance in a memory-search task was assessed both before (Time 1) and after (Time 2) the 12 weeks of exercise training. Results indicated that there was no significant change in memory-search performance over time as a function of exercise training. Analyses of the Time 2 RTs demonstrated that aspects of memory-search performance were related significantly both to subjects' initial (Time 1) level of fitness and to age, but not to the amount of change of fitness associated with aerobic exercise training over this 12-week duration in this age group. (PsycINFO Database Record (c) 2010 APA, all rights reserved)