Learning Curve
The Nature and Nurture of High IQ: An Extended Sensitive Period for Intellectual Development
Angela Brant et al.
Psychological Science, forthcoming
Abstract:
IQ predicts many measures of life success, as well as trajectories of brain development. Prolonged cortical thickening observed in individuals with high IQ might reflect an extended period of synaptogenesis and high environmental sensitivity or plasticity. We tested this hypothesis by examining the timing of changes in the magnitude of genetic and environmental influences on IQ as a function of IQ score. We found that individuals with high IQ show high environmental influence on IQ into adolescence (resembling younger children), whereas individuals with low IQ show high heritability of IQ in adolescence (resembling adults), a pattern consistent with an extended sensitive period for intellectual development in more-intelligent individuals. The pattern held across a cross-sectional sample of almost 11,000 twin pairs and a longitudinal sample of twins, biological siblings, and adoptive siblings.
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The Relative Benefits of Learning by Teaching and Teaching Expectancy
Logan Fiorella & Richard Mayer
Contemporary Educational Psychology, forthcoming
Abstract:
The purpose of this study was to explore the hypothesis that learning is enhanced through the act of teaching others. Specifically, two experiments aimed to disentangle the relative effects of teaching expectancy (i.e., preparing to teach) and actually teaching (i.e., explaining to others for instructional purposes) on learning. Some participants studied a lesson on the Doppler Effect without the expectation of later teaching the material and then took a comprehension test on the material (control group). Other students studied the same lesson with instructions that they would later teach the material; of those expecting to teach, some participants actually taught the material by presenting a brief video-recorded lecture before being tested (teaching group), whereas others only prepared to teach before being tested (preparation group). Results of Experiment 1 indicated that both the preparation group and teaching group significantly outperformed the control group on an immediate comprehension test (Teaching vs. Control: d = 0.82; Preparation vs. Control: d = 0.59). However, when the same test was given following a one-week delay (Experiment 2), only the teaching group significantly outperformed the control group (Teaching vs. Control: d = 0.79; Preparation vs. Control: d = 0.24). Overall, these findings suggest that when students actually teach the content of a lesson, they develop a deeper and more persistent understanding of the material than from solely preparing to teach.
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A Strong Interactive Link between Sensory Discriminations and Intelligence
Michael Melnick et al.
Current Biology, 3 June 2013, Pages 1013-1017
Abstract:
Early psychologists, including Galton, Cattell, and Spearman, proposed that intelligence and simple sensory discriminations are constrained by common neural processes, predicting a close link between them. However, strong supporting evidence for this hypothesis remains elusive. Although people with higher intelligence quotients (IQs) are quicker at processing sensory stimuli, these broadly replicated findings explain a relatively modest proportion of variance in IQ. Processing speed alone is, arguably, a poor match for the information processing demands on the neural system. Our brains operate on overwhelming amounts of information, and thus their efficiency is fundamentally constrained by an ability to suppress irrelevant information. Here, we show that individual variability in a simple visual discrimination task that reflects both processing speed and perceptual suppression strongly correlates with IQ. High-IQ individuals, although quick at perceiving small moving objects, exhibit disproportionately large impairments in perceiving motion as stimulus size increases. These findings link intelligence with low-level sensory suppression of large moving patterns - background-like stimuli that are ecologically less relevant. We conjecture that the ability to suppress irrelevant and rapidly process relevant information fundamentally constrains both sensory discriminations and intelligence, providing an information-processing basis for the observed link.
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Evolution of consciousness: Phylogeny, ontogeny, and emergence from general anesthesia
George Mashour & Michael Alkire
Proceedings of the National Academy of Sciences, 18 June 2013, Pages 10357-10364
Abstract:
Are animals conscious? If so, when did consciousness evolve? We address these long-standing and essential questions using a modern neuroscientific approach that draws on diverse fields such as consciousness studies, evolutionary neurobiology, animal psychology, and anesthesiology. We propose that the stepwise emergence from general anesthesia can serve as a reproducible model to study the evolution of consciousness across various species and use current data from anesthesiology to shed light on the phylogeny of consciousness. Ultimately, we conclude that the neurobiological structure of the vertebrate central nervous system is evolutionarily ancient and highly conserved across species and that the basic neurophysiologic mechanisms supporting consciousness in humans are found at the earliest points of vertebrate brain evolution. Thus, in agreement with Darwin's insight and the recent "Cambridge Declaration on Consciousness in Non-Human Animals," a review of modern scientific data suggests that the differences between species in terms of the ability to experience the world is one of degree and not kind.
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Spatial Training Improves Children's Mathematics Ability
Yi Ling Cheng & Kelly Mix
Journal of Cognition and Development, forthcoming
Abstract:
We tested whether mental rotation training improved math performance in 6- to 8-year-olds. Children were pretested on a range of number and math skills. Then one group received a single session of mental rotation training using an object completion task that had previously improved spatial ability in children this age (Ehrlich et al., 2006). The remaining children completed crossword puzzles instead. Children's posttest scores revealed that those in the spatial training group improved significantly on calculation problems. In contrast, children in the control group did not improve on any math tasks. Further analyses revealed that the spatial training group's improvement was largely due to better performance on missing term problems (e.g., 4 + __ = 11).
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James Lee & Christopher Chabris
Psychological Science, forthcoming
Abstract:
Identifying the precise locus of general cognitive ability (g) in the flow of information between perception and action is an important goal of differential psychology. To localize the negative correlation between g and reaction time to a specific processing stage, we administered a speeded number-comparison task to two groups differing in average g. The participants had to respond to two stimuli in each trial, which produced the well-known slowing of the second reaction time known as the psychological refractory period. The difference in the second reaction time favoring the high-g group doubled as the stimulus onsets became very close together. This finding affirms that the faster reaction times of higher-g individuals reflect an advantage exclusively in the serial bottleneck of central processing and not in the parallel peripheral stages.
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Paul Montgomery et al.
PLoS ONE, June 2013
Background: Omega-3 long-chain polyunsaturated fatty acids (LC-PUFA), especially DHA (docosahexaenonic acid) are essential for brain development and physical health. Low blood Omega-3 LC-PUFA have been reported in children with ADHD and related behavior/learning difficulties, as have benefits from dietary supplementation. Little is known, however, about blood fatty acid status in the general child population. We therefore investigated this in relation to age-standardized measures of behavior and cognition in a representative sample of children from mainstream schools.
Participants: 493 schoolchildren aged 7-9 years from mainstream Oxfordshire schools, selected for below average reading performance in national assessments at age seven.
Method: Whole blood fatty acids were obtained via fingerstick samples. Reading and working memory were assessed using the British Ability Scales (II). Behaviour (ADHD-type symptoms) was rated using the revised Conners' rating scales (long parent and teacher versions). Associations were examined and adjusted for relevant demographic variables.
Results: DHA and eicosapentaenoic acid (EPA), accounted for only 1.9% and 0.55% respectively of total blood fatty acids, with DHA showing more individual variation. Controlling for sex and socio-economic status, lower DHA concentrations were associated with poorer reading ability (std. OLS coeff. = 0.09, p = <.042) and working memory performance (0.14, p = <.001). Lower DHA was also associated with higher levels of parent rated oppositional behavior and emotional lability (-0.175, p = <.0001 and -0.178, p = <.0001).
Conclusions: In these healthy UK children with below average reading ability, concentrations of DHA and other Omega-3 LC-PUFA were low relative to adult cardiovascular health recommendations, and directly related to measures of cognition and behavior. These findings require confirmation, but suggest that the benefits from dietary supplementation with Omega-3 LC-PUFA found for ADHD, Dyspraxia, Dyslexia, and related conditions might extend to the general school population.
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GWAS of 126,559 Individuals Identifies Genetic Variants Associated with Educational Attainment
Cornelius Rietveld et al.
Science, 21 June 2013, Pages 1467-1471
Abstract:
A genome-wide association study of educational attainment was conducted in a discovery sample of 101,069 individuals and a replication sample of 25,490. Three independent SNPs are genome-wide significant (rs9320913, rs11584700, rs4851266), and all three replicate. Estimated effects sizes are small (R2 ≈ 0.02%), approximately 1 month of schooling per allele. A linear polygenic score from all measured SNPs accounts for ≈ 2% of the variance in both educational attainment and cognitive function. Genes in the region of the loci have previously been associated with health, cognitive, and central nervous system phenotypes, and bioinformatics analyses suggest the involvement of the anterior caudate nucleus. These findings provide promising candidate SNPs for follow-up work, and our effect size estimates can anchor power analyses in social-science genetics.
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Micaela Christopher et al.
Journal of Experimental Child Psychology, July 2013, Pages 453-467
Abstract:
This first cross-country twin study of individual differences in reading growth from post-kindergarten to post-second grade analyzed data from 487 twin pairs from the United States, 267 twin pairs from Australia, and 280 twin pairs from Scandinavia. Data from two reading measures were fit to biometric latent growth models. Individual differences for the reading measures at post-kindergarten in the United States and Australia were due primarily to genetic influences and to both genetic and shared environmental influences in Scandinavia. In contrast, individual differences in growth generally had large genetic influences in all countries. These results suggest that genetic influences are largely responsible for individual differences in early reading development. In addition, the timing of the start of formal literacy instruction may affect the etiology of individual differences in early reading development but have only limited influence on the etiology of individual differences in growth.
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Failure of Working Memory Training to Enhance Cognition or Intelligence
Todd Thompson et al.
PLoS ONE, May 2013
Abstract:
Fluid intelligence is important for successful functioning in the modern world, but much evidence suggests that fluid intelligence is largely immutable after childhood. Recently, however, researchers have reported gains in fluid intelligence after multiple sessions of adaptive working memory training in adults. The current study attempted to replicate and expand those results by administering a broad assessment of cognitive abilities and personality traits to young adults who underwent 20 sessions of an adaptive dual n-back working memory training program and comparing their post-training performance on those tests to a matched set of young adults who underwent 20 sessions of an adaptive attentional tracking program. Pre- and post-training measurements of fluid intelligence, standardized intelligence tests, speed of processing, reading skills, and other tests of working memory were assessed. Both training groups exhibited substantial and specific improvements on the trained tasks that persisted for at least 6 months post-training, but no transfer of improvement was observed to any of the non-trained measurements when compared to a third untrained group serving as a passive control. These findings fail to support the idea that adaptive working memory training in healthy young adults enhances working memory capacity in non-trained tasks, fluid intelligence, or other measures of cognitive abilities.
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Numerical ability predicts mortgage default
Kristopher Gerardi, Lorenz Goette & Stephan Meier
Proceedings of the National Academy of Sciences, forthcoming
Abstract:
Unprecedented levels of US subprime mortgage defaults precipitated a severe global financial crisis in late 2008, plunging much of the industrialized world into a deep recession. However, the fundamental reasons for why US mortgages defaulted at such spectacular rates remain largely unknown. This paper presents empirical evidence showing that the ability to perform basic mathematical calculations is negatively associated with the propensity to default on one's mortgage. We measure several aspects of financial literacy and cognitive ability in a survey of subprime mortgage borrowers who took out loans in 2006 and 2007, and match them to objective, detailed administrative data on mortgage characteristics and payment histories. The relationship between numerical ability and mortgage default is robust to controlling for a broad set of sociodemographic variables, and is not driven by other aspects of cognitive ability. We find no support for the hypothesis that numerical ability impacts mortgage outcomes through the choice of the mortgage contract. Rather, our results suggest that individuals with limited numerical ability default on their mortgage due to behavior unrelated to the initial choice of their mortgage.
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Longitudinal changes in college math students' implicit theories of intelligence
Rebecca Shively & Carey Ryan
Social Psychology of Education, June 2013, Pages 241-256
Abstract:
This study examined changes over time in implicit theories of intelligence and their relationships to help-seeking and academic performance. College algebra students completed questionnaires during the second week of classes and 2 weeks before the end of the semester (ns = 159 and 145, respectively; 61 students completed questionnaires at both waves). The questionnaires assessed entity and incremental implicit theories of general and math intelligence (beginning and end of semester) and help-seeking (end of semester). Results indicated that students had more incremental views of general than math intelligence. Further, their views became less incremental over the course of the semester; however, this decrease was greater for math than for general intelligence. Participants who exhibited a stronger incremental theory of general intelligence at the beginning of the semester subsequently reported greater help-seeking during the semester. Finally, students who had more entitative views of math intelligence earned lower course grades.
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Stuart Ritchie et al.
Psychology and Aging, June 2013, Pages 515-521
Abstract:
Recent reports suggest a causal relationship between education and IQ, which has implications for cognitive development and aging - education may improve cognitive reserve. In two longitudinal cohorts, we tested the association between education and lifetime cognitive change. We then tested whether education is linked to improved scores on processing-speed variables such as reaction time, which are associated with both IQ and longevity. Controlling for childhood IQ score, we found that education was positively associated with IQ at ages 79 (Sample 1) and 70 (Sample 2), and more strongly for participants with lower initial IQ scores. Education, however, showed no significant association with processing speed, measured at ages 83 and 70. Increased education may enhance important later life cognitive capacities, but does not appear to improve more fundamental aspects of cognitive processing.
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Idan Shalev et al.
Psychological Science, forthcoming
Abstract:
Why do more intelligent people live healthier and longer lives? One possibility is that intelligence tests assess health of the brain, but psychological science has lacked technology to evaluate this hypothesis. Digital retinal imaging, a new, noninvasive method to visualize microcirculation in the eye, may reflect vascular conditions in the brain. We studied the association between retinal vessel caliber and neuropsychological functioning in the representative Dunedin birth cohort. Wider venular caliber was associated with poorer neuropsychological functioning at midlife, independently of potentially confounding factors. This association was not limited to any specific test domain and extended to informants' reports of cohort members' cognitive difficulties in everyday life. Moreover, wider venular caliber was associated with lower childhood IQ tested 25 years earlier. The findings indicate that retinal venular caliber may be an indicator of neuropsychological health years before the onset of dementing diseases and suggest that digital retinal imaging may be a useful investigative tool for psychological science.