Findings

How Smart

Kevin Lewis

April 02, 2011

Parasite prevalence and the distribution of intelligence among the states of the USA

Christopher Eppig, Corey Fincher & Randy Thornhill
Intelligence, March-April 2011, Pages 155-160

Abstract:
In this study, we tested the parasite-stress hypothesis for the distribution of intelligence among the USA states: the hypothesis proposes that intelligence emerges from a developmental trade-off between maximizing brain vs. immune function. From this we predicted that among the USA states where infectious disease stress was high, average intelligence would be low and where infectious disease stress was low, average intelligence would be high. As predicted, we found that the correlation between average state IQ and infectious disease stress was - 0.67 (p < 0.0001) across the 50 states. Furthermore, when controlling the effects of wealth and educational variation among states, infectious disease stress was the best predictor of average state IQ.

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Rapid metabolic evolution in human prefrontal cortex

Xing Fu et al.
Proceedings of the National Academy of Sciences, forthcoming

Abstract:
Human evolution is characterized by the rapid expansion of brain size and drastic increase in cognitive capabilities. It has long been suggested that these changes were accompanied by modifications of brain metabolism. Indeed, human-specific changes on gene expression or amino acid sequence were reported for a number of metabolic genes, but actual metabolite measurements in humans and apes have remained scarce. Here, we investigate concentrations of more than 100 metabolites in the prefrontal and cerebellar cortex in 49 humans, 11 chimpanzees, and 45 rhesus macaques of different ages using gas chromatography-mass spectrometry (GC-MS). We show that the brain metabolome undergoes substantial changes, both ontogenetically and evolutionarily: 88% of detected metabolites show significant concentration changes with age, whereas 77% of these metabolic changes differ significantly among species. Although overall metabolic divergence reflects phylogenetic relationships among species, we found a fourfold acceleration of metabolic changes in prefrontal cortex compared with cerebellum in the human lineage. These human-specific metabolic changes are paralleled by changes in expression patterns of the corresponding enzymes, and affect pathways involved in synaptic transmission, memory, and learning.

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Individual differences in susceptibility to inattentional blindness

Janelle Seegmiller, Jason Watson & David Strayer
Journal of Experimental Psychology: Learning, Memory, and Cognition, forthcoming

Abstract:
Inattentional blindness refers to the finding that people do not always see what appears in their gaze. Though inattentional blindness affects large percentages of people, it is unclear if there are individual differences in susceptibility. The present study addressed whether individual differences in attentional control, as reflected by variability in working memory capacity, modulate susceptibility to inattentional blindness. Participants watched a classic inattentional blindness video (Simons & Chabris, 1999) and were instructed to count passes among basketball players, wherein 58% noticed the unexpected: a person wearing a gorilla suit. When participants were accurate with their pass counts, individuals with higher working memory capacity were more likely to report seeing the gorilla (67%) than those with lesser working memory capacity (36%). These results suggest that variability in attentional control is a potential mechanism underlying the apparent modulation of inattentional blindness across individuals.

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Improving general intelligence with a nutrient-based pharmacological intervention

Con Stough et al.
Intelligence, March-April 2011, Pages 100-107

Abstract:
Cognitive enhancing substances such as amphetamine and modafinil have become popular in recent years to improve acute cognitive performance particularly in environments in which enhanced cognition or intelligence is required. Nutraceutical nootropics, which are natural substances that have the ability to bring about acute or chronic changes in cognition have also been gaining popularity in a range of settings and applications including the workplace, driving and in the amelioration of age related cognitive decline. Huperzine A, Vinpocetine, Acetyl-l-carnitine, Rhodiola Rosea and Alpha-lipoic Acid are popular nutritional supplements that have shown promising benefits in improving a range of biological (e.g., blood flow, anti-inflammatory, anti-oxidant, and direct neurotransmitter effects) and cognitive processes from in vitro, animal and human clinical research. We report here the first human randomized clinical trial for cognition in which we administer a combination of Huperzine A, Vinpocetine, Acetyl-l-carnitine, R. Rosea and Alpha-lipoic acid (called Ceretrophin) vs placebo. Sixty participants (40 females and 20 males, with a mean age of 45.4 years, SD = 12.6) completed either the odd or even items from the Raven Advanced Progressive Matrices (APM) at baseline and the opposite odd or even items at week 4 after consuming either the combination nootropic or placebo. A significant study visit (time) × treatment condition interaction was found: F (1, 57) = 7.279, p = 0.009, partial η2 = .113, with paired samples t-tests revealing a significant improvement in mean APM score from baseline to retest (week 4) (t(34) = - 4.045, p < .001) for the CeretrophinTM group. Improvements in APM scores could be attributed to the active intervention over the placebo, indicating that the treatment improved general intelligence. Implications for improving our understanding of the biological basis of intelligence and pharmacologically improving human cognition are discussed.

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Changes in Brain Size during the Menstrual Cycle

Georg Hagemann et al.
PLoS ONE, February 2011, e14655

Background: There is increasing evidence for hormone-dependent modification of function and behavior during the menstrual cycle, but little is known about associated short-term structural alterations of the brain. Preliminary studies suggest that a hormone-dependent decline in brain volume occurs in postmenopausal, or women receiving antiestrogens, long term. Advances in serial MR-volumetry have allowed for the accurate detection of small volume changes of the brain. Recently, activity-induced short-term structural plasticity of the brain was demonstrated, challenging the view that the brain is as rigid as formerly believed.

Methodology/Principal Findings: We used MR-volumetry to investigate short-term brain volume changes across the menstrual cycle in women or a parallel 4 week period in men, respectively. We found a significant grey matter volume peak and CSF loss at the time of ovulation in females. This volume peak did not correlate with estradiol or progesterone hormone levels. Men did not show any significant brain volume alterations.

Conclusions/Significance: These data give evidence of short-term hormone-dependent structural brain changes during the menstrual cycle, which need to be correlated with functional states and have to be considered in structure-associated functional brain research.

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Walking and talking: Dual-task effects on street crossing behavior in older adults

Mark Neider et al.
Psychology and Aging, forthcoming

Abstract:
The ability to perform multiple tasks simultaneously has become increasingly important as technologies such as cell phones and portable music players have become more common. In the current study, we examined dual-task costs in older and younger adults using a simulated street crossing task constructed in an immersive virtual environment with an integrated treadmill so that participants could walk as they would in the real world. Participants were asked to cross simulated streets of varying difficulty while either undistracted, listening to music, or conversing on a cell phone. Older adults were more vulnerable to dual-task impairments than younger adults when the crossing task was difficult; dual-task costs were largely absent in the younger adult group. Performance costs in older adults were primarily reflected in timeout rates. When conversing on a cell phone, older adults were less likely to complete their crossing compared with when listening to music or undistracted. Analysis of time spent next to the street prior to each crossing, where participants were presumably analyzing traffic patterns and making decisions regarding when to cross, revealed that older adults took longer than younger adults to initiate their crossing, and that this difference was exacerbated during cell phone conversation, suggesting impairments in cognitive planning processes. Our data suggest that multitasking costs may be particularly dangerous for older adults even during everyday activities such as crossing the street.

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Heritability of Verbal and Performance Intelligence in a Pediatric Longitudinal Sample

Inge van Soelen et al.
Twin Research and Human Genetics, April 2011, Pages 119-128

Abstract:
The longitudinal stability of IQ is well-documented as is its increasing heritability with age. In a longitudinal twin study, we addressed the question to what extent heritability and stability differ for full scale (FSIQ), verbal (VIQ), and performance IQ (PIQ) in childhood (age 9-11 years), and early adolescence (age 12-14 years). Genetic and environmental influences and correlations over time were evaluated in an extended twin design, including Dutch twins and their siblings. Intelligence was measured by the Wechsler Intelligence Scale for children - Third version (WISC III). Heritability in childhood was 34% for FSIQ, 37% for VIQ, and 64% for PIQ, and increased up to 65%, 51%, and 72% in early adolescence. The influence of common environment decreased between childhood and early adolescence from explaining 43% of the phenotypic variance for FSIQ to 18% and from 42% for VIQ to 26%. For PIQ common environmental influences did not play a role, either in childhood or in early adolescence. The stability in FSIQ and VIQ across the 3-year interval (rp) was .72 for both measures and was explained by genetic and common environmental correlations across time (FSIQ, rg = .96, rc = 1.0; VIQ, rg =.78, rc = 1.0). Stability of PIQ (rp =.56) was lower and was explained by genetic influences (rg = .90). These results confirm the robust findings of increased heritability of general cognitive abilities during the transition from childhood to adolescence. Interestingly, results for PIQ differ from those for FSIQ and VIQ, in that no significant contribution of environment shared by siblings from the same family was detected.

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Breakfast consumption and cognitive function in adolescent schoolchildren

Simon Cooper, Stephan Bandelow & Mary Nevill
Physiology & Behavior, forthcoming

Abstract:
This study examined the effects of breakfast consumption on cognitive function, mood and blood glucose concentration in adolescent schoolchildren. With the institutions ethical advisory committee approval, 96 adolescents (12 to 15 years old) completed two randomly assigned trials (one following breakfast consumption and one following breakfast omission), scheduled 7 days apart. Cognitive function tests (visual search test, Stroop test and Sternberg paradigm), a mood questionnaire and a finger prick blood sample (in a subgroup of 60 participants) were completed immediately following breakfast and 120 min after the baseline measures. Following breakfast consumption, accuracy on the more complex level of the visual search test was higher than following breakfast omission (p = 0.021). Similarly, accuracy on the Stroop test was better maintained across the morning following breakfast consumption when compared to breakfast omission (p = 0.022). Furthermore, responses on the Sternberg paradigm were quicker later in the morning following breakfast consumption, particularly on the more complex levels (p = 0.012). Breakfast consumption also produced higher self-report energy and fullness, lower self-report tiredness and hunger and higher blood glucose concentrations (all p < 0.0005). Overall, the findings of the present study suggest that breakfast consumption enhances cognitive function in an adolescent population when compared to breakfast omission.

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Imagining a Way Out of the Gravity Bias: Preschoolers Can Visualize the Solution to a Spatial Problem

Amy Joh, Vikram Jaswal & Rachel Keen
Child Development, forthcoming

Abstract:
Can young children visualize the solution to a difficult spatial problem? Forty-eight 3-year-olds were tested in a spatial reasoning paradigm in which they were asked to predict the path of a ball moving through 1 of 3 intertwined tubes. One group of children was asked to visualize the ball rolling down the tube before they made their predictions, a second group was given identical instructions without being asked to use visual imagery, and a third group was given no instructions. Children in the visualization condition performed significantly better than those in the other conditions, suggesting that encouraging young children to use visual imagery may help them to reason through difficult problems.

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Betting on memory leads to metacognitive improvement by younger and older adults

Shannon McGillivray & Alan Castel
Psychology and Aging, March 2011, Pages 137-142

Abstract:
The present study examined how younger and older adults choose to selectively remember important information. Participants studied words paired with point values, and "bet" on whether they could later recall each word. If they bet on and recalled the word, they received the points, but if they failed to recall it, they lost those points. Participants (especially older adults) initially bet on more words than they later recalled, but greatly improved with task experience. The incorporation of rewards and penalties associated with metacognitive predictions, and multiple study-test trials, revealed that both younger and older adults can learn to maximize performance.

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The Effect Of Breastfeeding On Children's Educational Test Scores At Nine-Years Of Age: Results Of An Irish Cohort Study

Cathal McCrory & Richard Layte
Social Science & Medicine, forthcoming

Abstract:
This retrospective cross-sectional paper examines the relationship between early breastfeeding exposure and children's academic test scores at nine years of age independent of a wide range of possible confounders. The final sample comprised 8,226 nine-year-old school children participating in the first wave of the Growing Up in Ireland study. The children were selected through the Irish national school system using a 2-stage sampling method and were representative of the nine-year population. Information relating to breastfeeding initiation and exposure duration was obtained retrospectively at nine years of age via parental recall and children's academic performance was assessed using standardised Reading and Mathematics tests. Hierarchical linear regression analysis with robust standard errors to control for clustering at the school level was used to quantify the effect of breastfeeding on children's test scores. Propensity score matching was used to compare treatment effects across groups defined by their propensity to breastfeed. In unadjusted analysis, children who were breastfed scored 8.67 percentage points higher on reading and 7.42 percentage points higher on mathematics compared to those who were never breastfed. While the breastfeeding advantage attenuated appreciably when adjusted for a range of child, maternal, socio-economic and socio-environmental characteristics, children who were breastfed continued to enjoy a significant test score advantage of 3.24 (p<.001) and 2.23 (p<.001) percentage points on reading and mathematics respectively compared to those who were never breastfed. Any amount of breastfeeding was associated with significantly higher test scores than no exposure, but evidence of a dose-response relationship was weak. The results of the propensity score matching analysis indicated that the test score advantage of breastfed children is robust and that the magnitude of the effect varies across groups defined by their propensity to breastfeed, being largest amongst the most socially disadvantaged and falling to near zero among the most advantaged group.

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Alcohol Intake and Cognitive Abilities in Old Age: The Lothian Birth Cohort 1936 Study

Janie Corley et al.
Neuropsychology, March 2011, Pages 166-175

Objective: Moderate alcohol consumption has been associated with better cognitive performance in late adulthood, possibly by improving vascular health. Few studies have examined the potentially confounding roles of prior cognitive ability and social class in this relationship.

Method: Participants were 922 healthy adults about 70 years old in the Lothian Birth Cohort 1936 study, for whom there are IQ data from age 11. Alcohol consumption was obtained by self-report questionnaire. Cognitive outcome measures included general cognitive ability, speed of information processing, memory, and verbal ability.

Results: Moderate to substantial drinking (>2 units/day) was associated with better performance on cognitive tests than low-level drinking (≤2 units/day) or nondrinking in men and women. After adjusting for childhood IQ and adult social class, most of these associations were removed or substantially attenuated. After full adjustment, a small, positive association remained between overall alcohol intake and memory (women and men) and verbal ability (women only). Women's overall alcohol intake was derived almost exclusively from wine. In men, effects differed according to beverage type: wine and sherry-port consumption was associated with better verbal ability, but beer was associated with a poorer verbal ability and spirits intake was associated with better memory.

Conclusions: Prior intelligence and socioeconomic status influence both amount and type of alcohol intake and may partly explain the link between alcohol intake and improved cognitive performance at age 70. Alcohol consumption was found to make a small, independent contribution to memory performance and verbal ability, but these findings' clinical significance is uncertain.

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Hope, Pride, and Processing During Optimal and Nonoptimal Times of Day

Lisa Cavanaugh et al.
Emotion, February 2011, Pages 38-46

Abstract:
We examine the conditions under which the distinct positive emotions of hope versus pride facilitate more or less fluid cognitive processing. Using individuals' naturally occurring time of day preferences (i.e., morning vs. evening hours), we show that specific positive emotions can differentially influence processing resources. We argue that specific positive emotions are more likely to influence processing and behavior during nonoptimal times of day, when association-based processing is more likely. We show in three experiments that hope, pride, and a neutral state differentially influence fluid processing on cognitive tasks. Incidental hope facilitates fluid processing during nonoptimal times of day (compared with pride and neutral), improving performance on tasks requiring fluid intelligence (Experiment 1) and increasing valuation estimates on tasks requiring that preferences be constructed on the spot (Experiments 2 and 3). We also provide evidence that these differences in preference and valuation occur through a process of increased imagination (Experiment 3). We contribute to emotion theory by showing that different positive emotions have different implications for processing during nonoptimal times of day.

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Glucose regulation is associated with cognitive performance in young nondiabetic adults

Claude Messier et al.
Behavioural Brain Research, forthcoming

Abstract:
Several studies have documented an increased incidence of dementia among diabetic patients. In addition, impaired glucose regulation in both, younger and older adults, has been shown to be associated with neuropsychological deficits, particularly of episodic memory. The main purpose of this study was to examine this association in a large sample of young nondiabetic adults. All participants underwent a glucose tolerance test together with measures of insulin levels and lipids. Regression analyses revealed that glucoregulatory indices based on evoked glucose levels significantly associated with the verbal memory performance of 122 young adults, independent of demographic and vascular risk factors. Participants were assessed after drinking glucose or saccharin, using a repeated-measures design. There was no effect of glucose on cognitive performance. Glucoregulatory indices calculated on the basis of insulin levels or fasting glucose levels explained less cognitive variability compared to indices based on evoked glucose levels. Cardiovascular risk factors were associated with hyperinsulinemia but these factors were not associated with cognitive performance in this young adult group. These findings suggest that cognitive decrements are observable in young, nondiabetic adults, prior to the onset of impaired glucose regulation and diabetes.

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Effects of Cell Phone Radiofrequency Signal Exposure on Brain Glucose Metabolism

Nora Volkow et al.
Journal of the American Medical Association, 23 February 2011, Pages 808-813

Context: The dramatic increase in use of cellular telephones has generated concern about possible negative effects of radiofrequency signals delivered to the brain. However, whether acute cell phone exposure affects the human brain is unclear.

Objective: To evaluate if acute cell phone exposure affects brain glucose metabolism, a marker of brain activity.

Design, Setting, and Participants: Randomized crossover study conducted between January 1 and December 31, 2009, at a single US laboratory among 47 healthy participants recruited from the community. Cell phones were placed on the left and right ears and positron emission tomography with (18F)fluorodeoxyglucose injection was used to measure brain glucose metabolism twice, once with the right cell phone activated (sound muted) for 50 minutes ("on" condition) and once with both cell phones deactivated ("off" condition). Statistical parametric mapping was used to compare metabolism between on and off conditions using paired t tests, and Pearson linear correlations were used to verify the association of metabolism and estimated amplitude of radiofrequency-modulated electromagnetic waves emitted by the cell phone. Clusters with at least 1000 voxels (volume >8 cm3) and P < .05 (corrected for multiple comparisons) were considered significant.

Main Outcome Measure: Brain glucose metabolism computed as absolute metabolism (μmol/100 g per minute) and as normalized metabolism (region/whole brain).

Results: Whole-brain metabolism did not differ between on and off conditions. In contrast, metabolism in the region closest to the antenna (orbitofrontal cortex and temporal pole) was significantly higher for on than off conditions (35.7 vs 33.3 μmol/100 g per minute; mean difference, 2.4 [95% confidence interval, 0.67-4.2]; P = .004). The increases were significantly correlated with the estimated electromagnetic field amplitudes both for absolute metabolism (R = 0.95, P < .001) and normalized metabolism (R = 0.89; P < .001).

Conclusions: In healthy participants and compared with no exposure, 50-minute cell phone exposure was associated with increased brain glucose metabolism in the region closest to the antenna. This finding is of unknown clinical significance.

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Cognitive function in families with exceptional survival

Sandra Barral et al.
Neurobiology of Aging, forthcoming

Abstract:
The authors investigated whether cognitive function may be used as an endophenotype for longevity by assessing the cognitive performance of a family-based cohort consisting of 1380 individuals from 283 families recruited for exceptional survival in field centers in Boston, New York, Pittsburgh, and Denmark. Cognitive performance was assessed in the combined offspring of the Long Life Family Study (LLFS) probands and their LLFS siblings as compared with their spouses' cognitive performance. Our results indicate that the combined offspring of the LLFS probands and their siblings achieve significantly higher scores on both digit forward and backward tasks (p = 5 10-5 and p = 8 10-4 respectively) as well as on a verbal fluency task (p = 0.008) when compared with their spouse controls. No differences between groups were found for the other cognitive tests assessed. We conclude that LLFS family members in the offspring generation demonstrate significantly better performance on multiple tasks requiring attention, working memory, and semantic processing when compared with individuals without a family history of exceptional survival, suggesting that cognitive performance may serve as an important endophenotype for longevity.

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Intelligence of adolescents is related to their parents' educational level but not to family income

Gina Lemos, Leandro Almeida & Roberto Colom
Personality and Individual Differences, May 2011, Pages 1062-1067

Abstract:
Parental educational level and family income have been related to individual differences in intelligence. However, large and representative samples are hardly available. Here two samples of young and old adolescents totaling 3233 boys and girls completed an intelligence battery comprising abstract, numerical, verbal, mechanical, and spatial reasoning subtests. Parents' educational levels, family incomes, and adolescents' general intelligence (g) were simultaneously related using SEM (structural equation modeling) analyses. The main findings show that (1) parental education strongly predicts family differences in income, (2) family income is not related to adolescents' intelligence, and (3) parents' education predicts adolescents' intelligence regardless of family income. Because it is widely acknowledged that personal intelligence is the best predictor of educational differences, the next causal chain is endorsed: brighter parents reach higher levels of education, which allows approaching better occupations, and, therefore, they can create families with higher incomes. Adolescents from more affluent families tend to be brighter because their parents are brighter, not because they enjoy better family environments.

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The effect of background music and noise on the cognitive test performance of introverts and extraverts

Stacey Dobbs, Adrian Furnham & Alastair McClelland
Applied Cognitive Psychology, March/April 2011, Pages 307-313

Abstract:
Previous research has found that the performance of introverts on complex cognitive tasks is more negatively affected by distracters, e.g. music and background noise, than the performance of extraverts. The present study extends previous research by examining whether or not background noise would prove to be as distracting as music. In the presence of silence, background UK garage music and background noise, 118 female secondary school students carried out three cognitive tests. It was predicted that introverts would do less well on all of the tasks than extraverts in the presence of music and noise but in silence performance would be the same. A significant interaction was found on all three of the tasks. It was also predicted that there would be a main effect of background sound: Performance would be worse in the presence of music and noise than silence. Results confirmed this prediction with one exception. This study also found a positive correlation between extraversion and intelligence, the implications of which are also discussed. The findings support the Eysenckian hypothesis of the difference in optimum cortical arousal in introverts and extraverts.

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Walking Through Doorways Causes Forgetting: Further Explorations

Gabriel Radvansky, Sabine Krawietz & Andrea Tamplin
Quarterly Journal of Experimental Psychology, forthcoming

Abstract:
Previous research using virtual environments has revealed a location updating effect in which there is a decline in memory when people move from one location to another. Here we assess whether this effect reflects the influence of the experienced context, both in terms of the degree of immersion of a person in an environment, as suggested by some work in spatial cognition, or by a shift in context. In Experiment 1, the degree of immersion was reduced by using smaller displays. In comparison, in Experiment 2 an actual, rather than a virtual, environment was used, to maximize immersion. Location updating effects were observed under both of these conditions. In Experiment 3, the original encoding context was reinstated by having a person return to the original room in which objects were first encoded. However, inconsistent with an encoding specificity account, memory did not improve by reinstating this context. Finally, we did a further analysis of the results of this and previous experiments to assess the differential influence of foregrounding and retrieval interference. Overall, these data are interpreted in terms of the Event Horizon model of event cognition and memory.

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Aging increases inattentional blindness to the gorilla in our midst

Elizabeth Graham & Deborah Burke
Psychology and Aging, March 2011, Pages 162-166

Abstract:
When engaged in an attention-demanding task, people are surprisingly vulnerable to inattentional blindness - the failure to notice an unexpected event. Two theories of cognitive aging, attentional capacity models and inhibitory deficit models, make opposite predictions about age differences in susceptibility to inattentional blindness. We tested these predictions using an inattentional blindness paradigm developed by Simons and Chabris (1999) and found that older adults were more likely to experience inattentional blindness than young adults. These results are compatible with attentional capacity models of cognitive aging but not with current inhibitory deficit models.

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The effects of single bouts of aerobic exercise, exergaming, and videogame play on cognitive control

Kevin O'Leary et al.
Clinical Neurophysiology, forthcoming

Objective: The effects of single bouts of aerobic exercise, exergaming, and action videogame play on event-related brain potentials (ERPs) and task performance indices of cognitive control were investigated using a modified flanker task that manipulated demands of attentional inhibition.

Methods: Participants completed four counterbalanced sessions of 20 min of activity intervention (i.e., seated rest, seated videogame play, and treadmill-based and exergame-based aerobic exercise at 60% HRmax) followed by cognitive testing once heart rate (HR) returned to within 10% of pre-activity levels.

Results: Results indicated decreased RT interference following treadmill exercise relative to seated rest and videogame play. P3 amplitude was increased following treadmill exercise relative to rest, suggesting an increased allocation of attentional resources during stimulus engagement. The seated videogame and exergame conditions did not differ from any other condition.

Conclusions: The findings indicate that single bouts of treadmill exercise may improve cognitive control through an increase in the allocation of attentional resources and greater interference control during cognitively demanding tasks. However, similar benefits may not be derived following short bouts of aerobic exergaming or seated videogame participation.

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Neuroanatomical Correlates of Intellectual Ability Across the Life Span

Suzanne Goh et al.
Developmental Cognitive Neuroscience, forthcoming

Abstract:
Attempts to correlate measures of intellectual ability with localized anatomical imaging features of the brain have yielded variable findings distributed across frontal, parietal, and temporal lobes. To better define the gray and white matter correlates of intellectual ability and the effects of sex and age, we analyzed the brains of 105 healthy individuals, ages 7-57 years, who had a Full Scale Intelligence Quotient (FSIQ) of 70 or higher. We examined associations of FSIQ with cortical thickness and with white matter volume throughout the cerebrum. Thinning of left ventromedial and right dorsolateral prefrontal cortices correlated significantly with FSIQ. Sex modified correlations of cortical thickness with FSIQ in the left inferior frontal, left cingulate, and right dorsomedial prefrontal cortices. Correlations of local white matter volumes with FSIQ varied by age, with adults showing inverse correlations of white matter volume with FSIQ in a large territory of right frontal white matter likely corresponding to fiber tracts of the superior corona radiata and superior longitudinal fasciculus. These findings corroborate the role of frontal and parietal association cortices and long association white matter fibers in higher intelligence and suggest ways in which the neuroanatomical correlates of higher intelligence may vary by sex and age.

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Cardiorespiratory Fitness and the Flexible Modulation of Cognitive Control in Preadolescent Children

Matthew Pontifex et al.
Journal of Cognitive Neuroscience, June 2011, Pages 1332-1345

Abstract:
The influence of cardiorespiratory fitness on the modulation of cognitive control was assessed in preadolescent children separated into higher- and lower-fit groups. Participants completed compatible and incompatible stimulus-response conditions of a modified flanker task, consisting of congruent and incongruent arrays, while ERPs and task performance were concurrently measured. Findings revealed decreased response accuracy for lower- relative to higher-fit participants with a selectively larger deficit in response to the incompatible stimulus-response condition, requiring the greatest amount of cognitive control. In contrast, higher-fit participants maintained response accuracy across stimulus-response compatibility conditions. Neuroelectric measures indicated that higher-fit, relative to lower-fit, participants exhibited global increases in P3 amplitude and shorter P3 latency, as well as greater modulation of P3 amplitude between the compatible and incompatible stimulus-response conditions. Similarly, higher-fit participants exhibited smaller error-related negativity (ERN) amplitudes in the compatible condition, and greater modulation of the ERN between the compatible and incompatible conditions, relative to lower-fit participants who exhibited large ERN amplitudes across both conditions. These findings suggest that lower-fit children may have more difficulty than higher-fit children in the flexible modulation of cognitive control processes to meet task demands.

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Physiological Aspects of Flow Experiences: Skills-Demand-Compatibility Effects on Heart Rate Variability and Salivary Cortisol

Johannes Keller et al.
Journal of Experimental Social Psychology, forthcoming

Abstract:
This research addresses flow theory according to which the compatibility of skills and task demands involved in an activity elicits flow experiences that render the activity intrinsically rewarding. Departing from correlational research, we applied experimental paradigms designed to test the impact of a skills-demands-compatibility on the emergence of flow in computerized tasks. On the one hand, the results from self-reports support the balance hypothesis and indicate that skills-demands-compatibility results in a pleasurable flow experience. On the other hand, the results also indicate that skills-demands-compatibility resulted in (a) reduced heart rate variability indicating enhanced mental workload, and (b) stress as indicated by relatively high levels of salivary cortisol. These results indicate that flow experiences combine subjectively positive elements with physiological elements reflecting strainful tension and mental load.


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