Findings

Intelligence Gathering

Kevin Lewis

March 24, 2010

The reproduction of intelligence

Gerhard Meisenberg
Intelligence, March-April 2010, Pages 220-230

Abstract:
Although a negative relationship between fertility and education has been described consistently in most countries of the world, less is known about the relationship between intelligence and reproductive outcomes. Also the paths through which intelligence influences reproductive outcomes are uncertain. The present study uses the NLSY79 to analyze the relationship of intelligence measured in 1980 with the number of children reported in 2004, when the respondents were between 39 and 47 years old. Intelligence is negatively related to the number of children, with partial correlations (age controlled) of -.156, -.069, -.235 and -.028 for White females, White males, Black females and Black males, respectively. This effect is related mainly to the g-factor. It is mediated in part by education and income, and to a lesser extent by the more "liberal" gender attitudes of more intelligent people. In the absence of migration and with constant environment, genetic selection would reduce the average IQ of the US population by about .8 points per generation.

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How to Gain Eleven IQ Points in Ten Minutes: Thinking Aloud Improves Raven's Matrices Performance in Older Adults

Mark Fox & Neil Charness
Aging, Neuropsychology, and Cognition, March 2010, Pages 191-204

Abstract:
Few studies have examined the impact of age on reactivity to concurrent think-aloud (TA) verbal reports. An initial study with 30 younger and 31 older adults revealed that thinking aloud improves older adult performance on a short form of the Raven's Matrices (Bors & Stokes, 1998, Educational and Psychological Measurement, 58, p. 382) but did not affect other tasks. In the replication experiment, 30 older adults (mean age = 73.0) performed the Raven's Matrices and three other tasks to replicate and extend the findings of the initial study. Once again older adults performed significantly better only on the Raven's Matrices while thinking aloud. Performance gains on this task were substantial (d = 0.73 and 0.92 in Experiments 1 and 2, respectively), corresponding to a fluid intelligence increase of nearly one standard deviation.

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Methylphenidate facilitates learning-induced amygdala plasticity

Kay Tye, Lynne Tye, Jackson Cone, Evelien Hekkelman, Patricia Janak & Antonello Bonci
Nature Neuroscience, forthcoming

Abstract:
Although methylphenidate (Ritalin) has been used therapeutically for nearly 60 years, the mechanisms by which it acutely modifies behavioral performance are poorly understood. Here we combined intra-lateral amygdala in vivo pharmacology and ex vivo electrophysiology to show that acute administration of methylphenidate, as well as a selective dopamine transporter inhibitor, facilitated learning-induced strengthening of cortico-amygdala synapses through a postsynaptic increase in AMPA receptor-mediated currents, relative to those in saline-treated rats. Furthermore, local administration of methylphenidate in the lateral amygdala enhanced cue-reward learning through dopamine D1 receptor-dependent mechanisms and suppressed task-irrelevant behavior through D2 receptor-dependent mechanisms. These findings reveal critical and distinct roles for dopamine receptor subtypes in mediating methylphenidate-induced enhancements of neural transmission and learning performance.

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"In the recent UC Berkeley sleep study, 39 healthy young adults were divided into two groups - nap and no-nap. At noon, all the participants were subjected to a rigorous learning task intended to tax the hippocampus, a region of the brain that helps store fact-based memories. Both groups performed at comparable levels. At 2 p.m., the nap group took a 90-minute siesta while the no-nap group stayed awake. Later that day, at 6 p.m., participants performed a new round of learning exercises. Those who remained awake throughout the day became worse at learning. In contrast, those who napped did markedly better and actually improved in their capacity to learn." [UC Berkeley]

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To Scroll or Not to Scroll: Scrolling, Working Memory Capacity, and Comprehending Complex Texts

Christopher Sanchez & Jennifer Wiley
Human Factors: The Journal of the Human Factors and Ergonomics Society, October 2009, Pages 730-738

Objective: The purpose of these experiments was to examine the effects of user characteristics on learning from scrolling interfaces.

Background: Although scrolling Web pages are now common, few studies have explored the effects of scrolling on understanding the content that is being conveyed.

Method: This set of studies investigated whether presenting text in two particular formats has an effect on comprehension for readers who differ in working memory capacity.

Results: Results from both studies indicated that a scrolling format reduced understanding of complex topics from Web pages, especially for readers who were lower in working memory capacity.

Conclusion: These findings show that the way text is presented can interact with learner abilities to affect learning outcomes.

Application: These results have implications for both educational technology and human interfaces that present information using displays that can vary in size and construction.

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Genetic Covariation Between Brain Volumes and IQ, Reading Performance, and Processing Speed

Rebecca Betjemann, Erin Phinney Johnson, Holly Barnard, Richard Boada, Christopher Filley, Pauline Filipek, Erik Willcutt, John DeFries & Bruce Pennington
Behavior Genetics, March 2010, Pages 135-145

Abstract:
Although there has been much interest in the relation between brain size and cognition, few studies have investigated this relation within a genetic framework and fewer still in non-adult samples. We analyzed the genetic and environmental covariance between structural MRI data from four brain regions (total brain volume, neocortex, white matter, and prefrontal cortex), and four cognitive measures (verbal IQ (VIQ), performance IQ (PIQ), reading ability, and processing speed), in a sample of 41 MZ twin pairs and 30 same-sex DZ twin pairs (mean age at cognitive test = 11.4 years; mean age at scan = 15.4 years). Multivariate Cholesky decompositions were performed with each brain volume measure entered first, followed by the four cognitive measures. Consistent with previous research, each brain and cognitive measure was found to be significantly heritable. The novel finding was the significant genetic but not environmental covariance between brain volumes and cognitive measures. Specifically, PIQ shared significant common genetic variance with all four measures of brain volume (r g = .58-.82). In contrast, VIQ shared significant genetic influence with neocortex volume only (r g = .58). Processing speed was significant with total brain volume (r g = .79), neocortex (r g = .64), and white matter (r g = .89), but not prefrontal cortex. The only brain measure to share genetic influence with reading was total brain volume (r g = .32), which also shared genetic influences with processing speed.

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Adaptive memory: Ancestral priorities and the mnemonic value of survival processing

James Nairne & Josefa N.S. Pandeirada
Cognitive Psychology, forthcoming

Abstract:
Evolutionary psychologists often propose that humans carry around "stone-age" brains, along with a toolkit of cognitive adaptations designed originally to solve hunter-gatherer problems. This perspective predicts that optimal cognitive performance might sometimes be induced by ancestrally-based problems, those present in ancestral environments, rather than by adaptive problems faced more commonly in modern environments. This prediction was examined in four experiments using the survival processing paradigm, in which retention is tested after participants process information in terms of its relevance to fitness-based scenarios. In each of the experiments, participants remembered information better after processing its relevance in an ancestral environment (the grasslands), compared to a modern urban environment (a city), despite the fact that all scenarios described similar fitness-relevant problems. These data suggest that our memory systems may be tuned to ancestral priorities.

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Aerobic Exercise and Neurocognitive Performance: A Meta-Analytic Review of Randomized Controlled Trials

Patrick Smith, James Blumenthal, Benson Hoffman, Harris Cooper, Timothy Strauman, Kathleen Welsh-Bohmer, Jeffrey Browndyke & Andrew Sherwood
Psychosomatic Medicine, forthcoming

Objectives: To assess the effects of aerobic exercise training on neurocognitive performance. Although the effects of exercise on neurocognition have been the subject of several previous reviews and meta-analyses, they have been hampered by methodological shortcomings and are now outdated as a result of the recent publication of several large-scale, randomized, controlled trials (RCTs).

Methods: We conducted a systematic literature review of RCTs examining the association between aerobic exercise training on neurocognitive performance between January 1966 and July 2009. Suitable studies were selected for inclusion according to the following criteria: randomized treatment allocation; mean age ≥18 years of age; duration of treatment >1 month; incorporated aerobic exercise components; supervised exercise training; the presence of a nonaerobic-exercise control group; and sufficient information to derive effect size data.

Results: Twenty-nine studies met inclusion criteria and were included in our analyses, representing data from 2049 participants and 234 effect sizes. Individuals randomly assigned to receive aerobic exercise training demonstrated modest improvements in attention and processing speed (g = 0.158; 95% confidence interval [CI]; 0.055-0.260; p = .003), executive function (g = 0.123; 95% CI, 0.021-0.225; p = .018), and memory (g = 0.128; 95% CI, 0.015-0.241; p = .026).

Conclusions: Aerobic exercise training is associated with modest improvements in attention and processing speed, executive function, and memory, although the effects of exercise on working memory are less consistent. Rigorous RCTs are needed with larger samples, appropriate controls, and longer follow-up periods.

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Effects of Aerobic Exercise Training on Cognitive Function and Cortical Vascularity in Monkeys

I.J. Rhyu, J.A. Bytheway, S.J. Kohler, H. Lange, K.J. Lee, J. Boklewski, K. McCormick, N.I. Williams, G.B. Stanton, W.T. Greenough & J.L. Cameron
Neuroscience, forthcoming

Abstract:
This study examined whether regular exercise training, at a level that would be recommended for middle-aged people interested in improving fitness could lead to improved cognitive performance and increased blood flow to the brain in another primate species. Adult female cynomolgus monkeys were trained to run on treadmills for one hour a day, 5 days a week, for a 5 month period (n=16; 1.9±0.4 miles/day). A sedentary control group sat daily on immobile treadmills (n=8). Half of the runners had an additional sedentary period for 3 months at the end of the exercise period (n=8). In all groups, half of the monkeys were middle-aged (10-12 years old) and half were more mature (15-17 years old). Starting the fifth week of exercise training, monkeys underwent cognitive testing using the Wisconsin General Testing Apparatus (WGTA). Regardless of age, the exercising group learned to use the WGTA significantly faster (4.6±3.4 days) compared to controls (8.3±4.8 days; p=0.05). At the end of 5 months of running monkeys showed increased fitness, and the vascular volume fraction in the motor cortex in mature adult running monkeys was increased significantly compared to controls (p=0.029). However, increased vascular volume did not remain apparent after a three-month sedentary period. These findings indicate that the level of exercise associated with improved fitness in middle-aged humans is sufficient to increase both the rate of learning and blood flow to the cerebral cortex, at least during the period of regular exercise.

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In Italy, north-south differences in IQ predict differences in income, education, infant mortality, stature, and literacy

Richard Lynn
Intelligence, January-February 2010, Pages 93-100

Abstract:
Regional differences in IQ are presented for 12 regions of Italy showing that IQs are highest in the north and lowest in the south. Regional IQs obtained in 2006 are highly correlated with average incomes at r = 0.937, and with stature, infant mortality, literacy and education. The lower IQ in southern Italy may be attributable to genetic admixture with populations from the Near East and North Africa.

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Exploring the Nature of "Trader Intuition"

Antoine Bruguier, Steven Quartz & Peter Bossaerts
Journal of Finance, forthcoming

Abstract:
Experimental evidence has consistently confirmed the ability of uninformed traders, even novices, to infer information from the trading process. We hypothesized that ToM was involved after contrasting brain activation in subjects watching markets with and without insiders. ToM refers to the innate human capacity to discern malicious or benevolent intent. We find that skill in predicting price changes in markets with insiders correlates with scores on two ToM tests. We document GARCH-like persistence in transaction price changes that may help with reading markets when there are insiders.

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Human capital and objective indicators of career success: The mediating effects of cognitive ability and conscientiousness

Thomas Ng & Daniel Feldman
Journal of Occupational and Organizational Psychology, March 2010, Pages 207-235

Abstract:
The purpose of the current study is to examine the mediating processes through which human capital (e.g. education and work experience) contribute to objective indicators of career success (e.g. salaries and promotions). We are particularly interested in the ways in which cognitive ability and conscientiousness help explain the process through which human capital gets translated into performance effectiveness and tangible career attainments. Results from meta-analytical structural equation modelling show that individuals' cognitive ability and conscientiousness mediate the effects of both education and organizational tenure on in-role and extra-role job performance. Ultimately, both in-role and extra-role job performance positively influence employees' salaries and promotions. The article concludes with implications for theory development and management practice.

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Human Capital Development Before Age Five

Douglas Almond & Janet Currie
NBER Working Paper, March 2010

Abstract:
This chapter seeks to set out what Economists have learned about the effects of early childhood influences on later life outcomes, and about ameliorating the effects of negative influences. We begin with a brief overview of the theory which illustrates that evidence of a causal relationship between a shock in early childhood and a future outcome says little about whether the relationship in question biological or immutable. We then survey recent work which shows that events before five years old can have large long term impacts on adult outcomes. Child and family characteristics measured at school entry do as much to explain future outcomes as factors that labor economists have more traditionally focused on, such as years of education. Yet while children can be permanently damaged at this age, an important message is that the damage can often be remediated. We provide a brief overview of evidence regarding the effectiveness of different types of policies to provide remediation. We conclude with a list of some of (the many) outstanding questions for future research.

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Nap-dependent learning in infants

Almut Hupbach, Rebecca Gomez, Richard Bootzin & Lynn Nadel
Developmental Science, November 2009, Pages 1007-1012

Abstract:
Sleep has been shown to aid a variety of learning and memory processes in adults (Stickgold, 2005). Recently, we showed that infants' learning also benefits from subsequent sleep such that infants who nap are able to abstract the general grammatical pattern of a briefly presented artificial language (Gomez, Bootzin & Nadel, 2006). In the present study, we demonstrate, for the first time, long-term effects of sleep on memory for an artificial language. Fifteen-month-old infants who had napped within 4 hours of language exposure remembered the general grammatical pattern of the language 24 hours later. In contrast, infants who had not napped shortly after being familiarized with the language showed no evidence of remembering anything about the language. Our findings support the view that infants' frequent napping plays an essential role in establishing long-term memory.

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A systematic literature review of the average IQ of sub-Saharan Africans

Jelte Wicherts, Conor Dolan & Han van der Maas
Intelligence, January-February 2010, Pages 1-20

Abstract:
On the basis of several reviews of the literature, Lynn [Lynn, R., (2006). Race differences in intelligence: An evolutionary analysis. Augusta, GA: Washington Summit Publishers.] and Lynn and Vanhanen [Lynn, R., & Vanhanen, T., (2006). IQ and global inequality. Augusta, GA: Washington Summit Publishers.] concluded that the average IQ of the Black population of sub-Saharan Africa lies below 70. In this paper, the authors systematically review published empirical data on the performance of Africans on the following IQ tests: Draw-A-Man (DAM) test, Kaufman-Assessment Battery for Children (K-ABC), the Wechsler scales (WAIS & WISC), and several other IQ tests (but not the Raven's tests). Inclusion and exclusion criteria are explicitly discussed. Results show that average IQ of Africans on these tests is approximately 82 when compared to UK norms. We provide estimates of the average IQ per country and estimates on the basis of alternative inclusion criteria. Our estimate of average IQ converges with the finding that national IQs of sub-Saharan African countries as predicted from several international studies of student achievement are around 82. It is suggested that this estimate should be considered in light of the Flynn Effect. It is concluded that more psychometric studies are needed to address the issue of measurement bias of western IQ tests for Africans.

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Knowledge applied to new domains: The unconscious succeeds where the conscious fails

Ryan Scott & Zoltan Dienes
Consciousness and Cognition, March 2010, Pages 391-398

Abstract:
A common view holds that consciousness is needed for knowledge acquired in one domain to be applied in a novel domain. We present evidence for the opposite; where the transfer of knowledge is achieved only in the absence of conscious awareness. Knowledge of artificial grammars was examined where training and testing occurred in different vocabularies or modalities. In all conditions grammaticality judgments attributed to random selection showed above-chance accuracy (60%), while those attributed to conscious decisions did not. Participants also rated each string's familiarity and performed a perceptual task assessing fluency. Familiarity was predicted by repetition structure and was thus related to grammaticality. Fluency, though increasing familiarity, was unrelated to grammaticality. While familiarity predicted all judgments only those attributed to random selection showed a significant additional contribution of grammaticality, deriving primarily from chunk novelty. In knowledge transfer, as in visual perception (Marcel, 1993), the unconscious may outperform the conscious.


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