On your mind

Kevin Lewis

July 02, 2010

Parasite prevalence and the worldwide distribution of cognitive ability

Christopher Eppig, Corey Fincher & Randy Thornhill
Proceedings of the Royal Society B, forthcoming

In this study, we hypothesize that the worldwide distribution of cognitive ability is determined in part by variation in the intensity of infectious diseases. From an energetics standpoint, a developing human will have difficulty building a brain and fighting off infectious diseases at the same time, as both are very metabolically costly tasks. Using three measures of average national intelligence quotient (IQ), we found that the zero-order correlation between average IQ and parasite stress ranges from r = −0.76 to r = −0.82 (p < 0.0001). These correlations are robust worldwide, as well as within five of six world regions. Infectious disease remains the most powerful predictor of average national IQ when temperature,  distance from Africa, gross domestic product per capita and several measures of education are controlled for. These findings suggest that the Flynn effect may be caused in part by the decrease in the intensity of infectious diseases as nations develop.


National IQs calculated and validated for 108 nations

Richard Lynn & Gerhard Meisenberg
Intelligence, July-August 2010, Pages 353-360

We estimate the validity of the national IQs presented by Lynn and Vanhanen (2002, 2006) by examining whether they are consistent with the educational attainment of school students in math, science and reading comprehension in 108 countries and provinces. The educational attainment scores in a number of studies are integrated to give EAs (educational attainments) for 86 countries and provinces that have measured IQs. The correlation of EA with measured IQ (N = 86 countries) is .917, and with measured + estimated IQ (N = 108 countries) is .907. Corrected for attenuation, r = 1.0. The quality of the data is evaluated, and the discrepancy between IQ and EA was greater for countries with low data quality, especially low quality of the EA data. There are no major anomalies in the relationship between IQ and EA in individual world regions. To some extent IQ and EA predict each other even within world regions. These results show that national IQs have a high degree of validity.


Chinese Number Words, Culture, and Mathematics Learning

Sharon Sui Ngan Ng & Nirmala Rao
Review of Educational Research, June 2010, Pages 180-206

This review evaluates the role of language — specifically, the Chinese-based system of number words and the simplicity of Chinese mathematical terms — in explaining the relatively superior performance of Chinese and other East Asian students in cross-national studies of mathematics achievement. Relevant research is critically reviewed focusing on linguistic and cultural influences. The review (a) provides equivocal findings about the extent to which number words in the Chinese language afford benefits for mathematics learning; (b) indicates that cultural and contextual factors are gaining prominence in accounting for the superior performance of East Asian students in cross-national studies; and (c) yields emerging evidence from neuroscience that highlights interrelationships among language, cultural beliefs, and mathematics learning. Although it is not possible to disentangle the influences of linguistic, cultural, and contextual factors on mathematics performance, language is still seen as contributing to early cross-national differences in mathematics attainment.


Fluid cognitive ability is associated with greater exposure and smaller reactions to daily stressors

Robert Stawski, David Almeida, Margie Lachman, Patricia Tun & Christopher Rosnick
Psychology and Aging, June 2010, Pages 330-342

The authors of this study investigated whether fluid cognitive ability predicts exposure and emotional reactivity to daily stressors. A national sample of adults from the Midlife in the United States study and the National Study of Daily Experiences (N = 1,202) who had a mean age of 57 years (SD = 12; 56% women, 44% men) completed positive and negative mood reports as well as a stressor diary on 8 consecutive evenings via telephone. Participants also completed a telephone-based battery of tests measuring fluid cognitive ability. Higher levels of fluid cognitive ability were associated with greater exposure to work- and home-related overload stressors. Possessing higher levels of fluid cognitive ability was associated with smaller stressor-related increases in negative mood, primarily for interpersonal tensions and network stressors, and smaller stressor-related decreases in positive mood for interpersonal tensions. Furthermore, fluid cognitive ability was unrelated to subjective severity ratings of the stressors reported. Discussion focuses on the role of fluid cognitive ability in daily stress processes.


Transcranial Pulsed Ultrasound Stimulates Intact Brain Circuits

Yusuf Tufail et al.
Neuron, 10 June 2010, Pages 681-694

Electromagnetic-based methods of stimulating brain activity require invasive procedures or have other limitations. Deep-brain stimulation requires surgically implanted electrodes. Transcranial magnetic stimulation does not require surgery, but suffers from low spatial resolution. Optogenetic-based approaches have unrivaled spatial precision, but require genetic manipulation. In search of a potential solution to these limitations, we began investigating the influence of transcranial pulsed ultrasound on neuronal activity in the intact mouse brain. In motor cortex, ultrasound-stimulated neuronal activity was sufficient to evoke motor behaviors. Deeper in subcortical circuits, we used targeted transcranial ultrasound to stimulate neuronal activity and synchronous oscillations in the intact hippocampus. We found that ultrasound triggers TTX-sensitive neuronal activity in the absence of a rise in brain temperature (<0.01°C). Here, we also report that transcranial pulsed ultrasound for intact brain circuit stimulation has a lateral spatial resolution of approximately 2 mm and does not require exogenous factors or surgical invasion.


Does Parental Education have a Moderating Effect on the Genetic and Environmental Influences of General Cognitive Ability in Early Adulthood?

Michael Grant, William Kremen, Kristen Jacobson, Carol Franz, Hong Xian, Seth Eisen, Rosemary Toomey, Ruth Murray & Michael Lyons
Behavior Genetics, July 2010, Pages 438-446

Hereditary influences account for a substantial proportion of the variance in many cognitive abilities. However, there is increasing recognition that the relative importance of genetic and environmental influences may vary across different socioeconomic levels. The overall goal of the present study was to examine whether parental education has a moderating effect on genetic and environmental influences of general cognitive ability in early adulthood (age 19.6 ± 1.5). Participants were 5,955 male twins from the Vietnam Era Twin (VET) Registry. Significant effects of parental education on mean level of general cognitive ability scores were found, but a model without moderating effects of parental education on genetic or environmental influences on cognitive scores proved to be the best fitting model. Some, but not all, previous studies have found significant moderating effects; however, no consistent pattern emerged that could account for between-study differences regarding moderating effects on genetic and environmental influences.


The (b)link between creativity and dopamine: Spontaneous eye blink rates predict and dissociate divergent and convergent thinking

Soghra Akbari Chermahini & Bernhard Hommel
Cognition, June 2010, Pages 458-465

Human creativity has been claimed to rely on the neurotransmitter dopamine, but evidence is still sparse. We studied whether individual performance (N = 117) in divergent thinking (alternative uses task) and convergent thinking (remote association task) can be predicted by the individual spontaneous eye blink rate (EBR), a clinical marker of dopaminergic functioning. EBR predicted flexibility in divergent thinking and convergent thinking, but in different ways. The relationship with flexibility was independent of intelligence and followed an inverted U-shape function with medium EBR being associated with greatest flexibility. Convergent thinking was positively correlated with intelligence but negatively correlated with EBR, suggesting that higher dopamine levels impair convergent thinking. These findings support the claim that creativity and dopamine are related, but they also call for more conceptual differentiation with respect to the processes involved in creative performance.


Location in cognitive and residential space at age 70 reflects a lifelong trait over parental and environmental circumstances: The Lothian Birth Cohort 1936

Wendy Johnson, Alan Gow, Janie Corley, John Starr & Ian Deary
Intelligence, July-August 2010, Pages 402-411

Though mental ability tends to be relatively stable throughout the lifespan, many still argue that late life cognitive function largely reflects education, social class, and environmental circumstances. Instead, it may be that early life cognitive function contributes to each of these in turn, as well as to late life cognitive function. This paper reports the contribution of IQ measured at age 11, adjusting for childhood measures of parental social status, to variation in educational and social class attainment in adulthood, and to cognitive function and environmental quality at age 70. Participants were the1091 members of the Lothian Birth Cohort 1936. They were born in 1936 and participated in the Scottish Mental Survey 1947. They were living independently in the general area of the City of Edinburgh, Scotland at the time of recruitment and assessment for this study at about age 70. Ages 11 and 70 IQs assessed using the same Moray House Test were correlated .69, and then .61 after adjustment for participants’ own educational and social class attainment, as well as for those of their fathers in childhood. Age 11 IQ was correlated .30 with age 70 environmental quality, and it remained correlated at .15 after adjustment. The attainment measures had significant but much smaller effects on both outcome measures. We conclude that both cognitive function and life circumstances at age 70 reflect lifelong cognitive function to a greater degree than they do life circumstances.


Two by Two: A Twin Study of Second-Language Acquisition

Philip Dale, Nicole Harlaar, Claire Haworth & Robert Plomin
Psychological Science, May 2010, Pages 635-640

In this report, we provide initial results of the first application of the classic twin design to second-language acquisition. The analysis was conducted on assessments teachers made using United Kingdom National Curriculum standards and included 604 pairs of 14-year-old twins. The results demonstrate substantial heritability (.67) and low influence of shared environment (.13) on this measure of second-language acquisition. The heritability of second-language acquisition at 14 years is comparable to the heritability of the two first-language acquisition measures obtained at 12 and 14 years, respectively, and is higher than heritability estimates previously published for first-language acquisition in early childhood. Multivariate behavior genetic analyses suggest very high, but not complete, overlap of genetic influences on first- and second-language acquisition, and less overlap between shared environmental influences on the two domains.


Comparisons of Creative Styles and Personality Types Between American and Taiwanese College Students and the Relationship Between Creative Potential and Personality Types

Yiling Cheng, Kyung Hee Kim & Michael Hull
Psychology of Aesthetics, Creativity, and the Arts, May 2010, Pages 103-112

The purpose of the study was to compare differences in creative styles (Kirton, 1976) and personality types between Americans and Taiwanese and to examine the relationships among various personality types and creative potential. Creative potential was measured by the Torrance Test of Creative Thinking-Figural, and personality types were measured by the Keirsey Temperament Sorter II. Ninety-three American and 76 Taiwanese college students specializing in teacher education participated in this study. The results indicated that Americans are more adaptively creative than Taiwanese, whereas there is no difference between the two groups in Innovative creative style. The results also indicated that there are significant relationships between Adaptive creative style and Intuition, between Creative Strengths and Intuition, and between Creative Strengths and Perceiving. It is concluded that there is a cultural difference in creative potential and personality types and that there are relationships between particular subscales of creativity and personality types.


Items on the left are better remembered

Sergio Della Sala, Stephen Darling & Robert Logie
Quarterly Journal of Experimental Psychology, May 2010, Pages 848-855

Neurologically intact individuals show a spatial processing bias in perception tasks, specifically showing a bias towards the left in bisecting lines. We present evidence for a novel finding that a leftwards bias occurs in short-term memory for recently presented arbitrary bindings of visual features. Three experiments are reported, two of which involve a total of over 60,000 participants with a small number of trials for each. Experiment 3 involved a larger number of trials for each of 144 participants. Participants reproduced from immediate memory arrays of shape-colour-location bindings. In all three experiments, significantly more errors were observed in reproduction of items presented on the right of the array than on the left. Results could not be accounted for by perceptual errors, or by order of presentation or order of reproduction. Findings suggest that items presented on the left are better remembered, indicating a spatial asymmetry in forming or retrieving feature bindings in visual short-term memory.


Newborn infants learn during sleep

William Fifer, Dana Byrd, Michelle Kaku, Inge-Marie Eigsti, Joseph Isler, Jillian Grose-Fifer, Amanda Tarullo & Peter Balsam
Proceedings of the National Academy of Sciences, 1 June 2010, Pages 10320-10323

Newborn infants must rapidly adjust their physiology and behavior to the specific demands of the novel postnatal environment. This adaptation depends, at least in part, on the infant's ability to learn from experiences. We report here that infants exhibit learning even while asleep. Bioelectrical activity from face and scalp electrodes was recorded from neonates during an eye movement conditioning procedure in which a tone was followed by a puff of air to the eye. Sleeping newborns rapidly learned the predictive relationship between the tone and the puff. Additionally, in the latter part of training, these infants exhibited a frontally maximum positive EEG slow wave possibly reflecting memory updating. As newborns spend most of their time sleeping, the ability to learn about external stimuli in the postnatal environment during nonawake states may be crucial for rapid adaptation and infant survival. Furthermore, because eyelid conditioning reflects functional cerebellar circuitry, this method potentially offers a unique approach for early identification of infants at risk for a range of developmental disorders including autism and dyslexia.


The effect of handedness on academic ability: A multivariate linear mixed model approach

Christopher Cheyne, Neil Roberts, Tim Crow, Stuart Leask & Marta Garca-Fiana
Laterality: Asymmetries of Body, Brain and Cognition, July 2010, Pages 451-464

In recent years questions have arisen about whether there are any links between handedness and academic abilities as well as other factors. In this study we investigate the effects of gender, writing hand, relative hand skill, and UK region on mathematics and reading test scores by applying a multivariate linear mixed-effects model. A data sample based on 11,847 11-year-old pupils across the UK from the National Child Development Study was considered for the analysis. Our results show that pupils who write with one hand while having better skill with their other hand (i.e., inconsistent writing hand and superior hand) obtained lower test scores in both reading and mathematics than pupils with consistent writing hand and superior hand. Furthermore, we confirm previous findings that degree of relative hand skill has a significant effect on both reading and maths scores and that this association is not linear. We also found higher scores of reading in children from the south of England, and of mathematics in children from the south of England and Scotland, when compared to other UK regions.


The functional origins of speech-related hand gestures

Ian Whishaw, Lori-Ann Sacrey, Scott Travis, Gita Gholamrezaei & Jenni Karl
Behavioural Brain Research, forthcoming

Many theories of language posit its recent evolution, perhaps contemporaneous with the evolution of Homo sapiens. The embodied language theory, however, in proposing that language includes gestures, provides an avenue for tracing language origins to phylogenetically earlier ancestral species. Here, evidence that the structure of functional hand movements (e.g., reaching for food, climbing a ladder, or crawling), in rats and humans is similar is presented. The structure of these functional hand movements is then compared to speech-related hand gestures in humans. The sequence of language-related gestures are also found to be characteristic of functional hand movements. It is suggested that these findings show that the arm and hand gestures that accompany human speech are derived from the same neural substrates that produces functional movements. Additionally, evidence is reviewed that supports the idea that speech related gestures resemble the movements elicited by long-train stimulation of the primate motor cortex. Together, this evidence suggests that speech related hand gesture have their evolutionary origins in functional hand movements of ancestral nonprimate and primate species and may be constrained by the neural substrate for those movements. These findings are further discussed in relation to the idea that speech-related gestures reflect forelimb motor cortex contributions to embodied language.


Cerebral blood flow differences between long-term meditators and non-meditators

Andrew Newberg, Nancy Wintering, Mark Waldman, Daniel Amen, Dharma Khalsa & Abass Alavi
Consciousness and Cognition, forthcoming

We have studied a number of long-term meditators in previous studies. The purpose of this study was to determine if there are differences in baseline brain function of experienced meditators compared to non-meditators. All subjects were recruited as part of an ongoing study of different meditation practices. We evaluated 12 advanced meditators and 14 non-meditators with cerebral blood flow (CBF) SPECT imaging at rest. Images were analyzed with both region of interest and statistical parametric mapping. The CBF of long-term meditators was significantly higher (p < .05) compared to non-meditators in the prefrontal cortex, parietal cortex, thalamus, putamen, caudate, and midbrain. There was also a significant difference in the thalamic laterality with long-term meditators having greater asymmetry. The observed changes associated with long-term meditation appear in structures that underlie the attention network and also those that relate to emotion and autonomic function.


Rage against the machines: How subjects play against learning algorithms

Peter Duersch, Albert Kolb, Jörg Oechssler & Burkhard Schipper
Economic Theory, June 2010, Pages 407-430

We use a large-scale internet experiment to explore how subjects learn to play against computers that are programmed to follow one of a number of standard learning algorithms. The learning theories are (unbeknown to subjects) a best response process, fictitious play, imitation, reinforcement learning, and a trial & error process. We explore how subjects’ performances depend on their opponents’ learning algorithm. Furthermore, we test whether subjects try to influence those algorithms to their advantage in a forward-looking way (strategic teaching). We find that strategic teaching occurs frequently and that all learning algorithms are subject to exploitation with the notable exception of imitation.


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