Differences In Intelligence Test Scores Research Articles

The long-term cognitive consequences of early childhood malnutrition: The case of famine in Ghana

We examine the role of early childhood health in human capital accumulation. Using a unique data set from Ghana with comprehensive information on individual, family, community, school quality characteristics and a direct measure of intelligence together with test scores, we examine the long-term cognitive effects of the 1983 famine on survivors. We show that differences in intelligence test scores can be robustly explained by the differential impact of the famine in different parts of the country and the impacts are most severe for children under two years of age during the famine. We also account for model uncertainty by using Bayesian Model Averaging.

The Long-Term Cognitive Consequences of Early Childhood Malnutrition: The Case of Famine in Ghana

We examine the role of early childhood health in human capital accumulation. Using a unique data set from Ghana with comprehensive information on individual, family, community, school quality characteristics and a direct measure of intelligence together with test scores, we examine the long term cognitive effects of the 1983 famine on survivors. We show that differences in intelligence test scores can be robustly explained by the differential impact of the famine in different parts of the country and children under two years during the famine were most adversely affected. We also account for model uncertainty by using Bayesian Model Averaging.

Race and IQ: A Theory-Based Review of the Research in Richard Nisbett ’ s Intelligence and How to Get It

We provide a detailed review of data from psychology, genetics, and neuroscience in a point-counterpoint for- mat to enable readers to identify the merits and demerits of each side of the debate over whether the culture-only (0% ge- netic-100% environmental) or nature + nurture model (50% genetic-50% environmental) best explains mean ethnic group differences in intelligence test scores: Jewish (mean IQ = 113), East Asian (106), White (100), Hispanic (90), South Asian (87), African American (85), and sub-Saharan African (70). We juxtapose Richard Nisbett's position, expressed in his book Intelligence and How to Get It, with our own, to examine his thesis that cultural factors alone are sufficient to explain the differences and that the nature + nurture model we have presented over the last 40 years is unnecessary. We review the evidence in 14 topics of contention: (1) data to be explained; (2) malleability of IQ test scores; (3) culture- loaded versus g-loaded tests; (4) stereotype threat, caste, and X factors; (5) reaction-time measures; (6) within-race heri- tability; (7) between-race heritability; (8) sub-Saharan African IQ scores; (9) race differences in brain size; (10) sex dif- ferences in brain size; (11) trans-racial adoption studies; (12) racial admixture studies; (13) regression to the mean effects; and (14) human origins research and life-history traits. We conclude that the preponderance of evidence demonstrates that in intelligence, brain size, and other life history traits, East Asians average higher than do Europeans who average higher do South Asians, African Americans, or sub-Saharan Africans. The group differences are between 50 and 80% heritable.

Exploring possible neural mechanisms of intelligence differences using processing speed and working memory tasks: An fMRI study

To explore the possible neural foundations of individual differences in intelligence test scores, we examined the associations between Raven's Matrices scores and two tasks that were administered in a functional magnetic resonance imaging (fMRI) setting. The two tasks were an n-back working memory ( N = 37) task and inspection time ( N = 47). The subjects were members of the Aberdeen Birth Cohort 1936, aged in their mid–late 60s when tested for this study. Performance on both tasks was correlated significantly with scores on Raven's Matrices. In the inspection time task there were regions with significant correlations between the neural activity (BOLD response) and performance but not between BOLD response and scores on Raven's Matrices. In the working memory task there were no significant correlations between BOLD response and either performance or scores on Raven's Matrices. Moreover, there was almost no mediation of the Raven's Matrices versus n-back and inspection time scores correlations by the respective BOLD response. These findings partially replicate important aspects of a prominent report in this field [Gray, J.R., Chabris, C.F., & Braver, T.S. (2003). Neural mechanisms of general fluid intelligence. Nature Neuroscience, 6, 316–322.], but have also extended the those finding into both a unique population and a novel functional task.

Age and Ability Affect Practice Gains in Longitudinal Studies of Cognitive Change

During a 20-year longitudinal study, 5,842 participants aged 49 to 93 years significantly improved over two to four successive experiences of the Heim AH4-1 intelligence test (first published in 1970), even with between-test intervals of 4 years and longer. After we considered significant attrition by death and dropout and the effects of gender, socioeconomic advantage, and recruitment cohort, we found that participants with high intelligence test scores showed greater improvement than did those with lower intelligence test scores. Practice gains also reduced with age, even after we took into consideration the individual differences in intelligence test scores. This emphasizes the methodological point that neglect of individual differences in improvement during longitudinal studies underestimates age-related changes in younger and more able participants and the theoretical point that, like all experiences during everyday life, participation in longitudinal studies alters the ability of aging humans to cope with cognitive demands to different extents according to their baseline abilities.

The Parieto-Frontal Integration Theory (P-FIT) of intelligence: Converging neuroimaging evidence

"Is there a biology of intelligence which is characteristic of the normal human nervous system?" Here we review 37 modern neuroimaging studies in an attempt to address this question posed by Halstead (1947) as he and other icons of the last century endeavored to understand how brain and behavior are linked through the expression of intelligence and reason. Reviewing studies from functional (i.e., functional magnetic resonance imaging, positron emission tomography) and structural (i.e., magnetic resonance spectroscopy, diffusion tensor imaging, voxel-based morphometry) neuroimaging paradigms, we report a striking consensus suggesting that variations in a distributed network predict individual differences found on intelligence and reasoning tasks. We describe this network as the Parieto-Frontal Integration Theory (P-FIT). The P-FIT model includes, by Brodmann areas (BAs): the dorsolateral prefrontal cortex (BAs 6, 9, 10, 45, 46, 47), the inferior (BAs 39, 40) and superior (BA 7) parietal lobule, the anterior cingulate (BA 32), and regions within the temporal (BAs 21, 37) and occipital (BAs 18, 19) lobes. White matter regions (i.e., arcuate fasciculus) are also implicated. The P-FIT is examined in light of findings from human lesion studies, including missile wounds, frontal lobotomy/leukotomy, temporal lobectomy, and lesions resulting in damage to the language network (e.g., aphasia), as well as findings from imaging research identifying brain regions under significant genetic control. Overall, we conclude that modern neuroimaging techniques are beginning to articulate a biology of intelligence. We propose that the P-FIT provides a parsimonious account for many of the empirical observations, to date, which relate individual differences in intelligence test scores to variations in brain structure and function. Moreover, the model provides a framework for testing new hypotheses in future experimental designs.

African IQ and Mental Retardation

Rushton and Jensen (2005), in an extensive review of racial differences in intelligence test scores, assert that some part of the difference between blacks and whites in mean intelligence (IQ) scores is genetic in origin. They cite earlier reviews by Lynn (1991) and by Lynn and Vanhanen (2002), as well as several more recent studies, which are said to indicate that the mean IQ of sub-Saharan black Africans is about 70 - at the borderline of mental retardation. The present article reviews critically both the original studies and the ways in which the reviewers have described the findings of the studies.

Ethnic Differences in Children's Intelligence Test Scores: Role of Economic Deprivation, Home Environment, and Maternal Characteristics

We examine differences in intelligence test scores of black and white 5-year-olds. The Infant Health and Development Program data set includes 483 low birthweight premature children who were assessed with the Wechsler Preschool and Primary Scale of Intelligence. These children had been followed from birth, with data on neighborhood and family poverty, family structure, family resources, maternal characteristics, and home environment collected over the first 5 years of life. Black children's IQ scores were 1 SD lower than those of white children. Adjustments for ethnic differences in poverty reduced the ethnic differential by 52%. Adjustments for maternal education and whether the head of household was female did not reduce the ethnic difference further. However, differences in home environment reduced the ethnic differential by an additional 28%. Adjustments for economic and social differences in the lives of black and white children all but eliminate differences in the IQ scores between these two groups.

Superior Intellect?: Sincere Fictions of the White Self

This article investigates claims of superior White intelligence from an emerging race relations perspective that describes the symbolic labor used to construct a psychological and cultural self that legitimizes White privilege. It examines the sincere fictions of the White self offered in A Study of American Intelligence (1923) and The Bell Curve (1994), whose similar outlooks suggest a fundamental consistency in White self-concept over time. Representations of the White self and some of the sincere fictions offered in these works are critiqued, including the construction of equality as the prerogative of Whites, myths of the superior intellect of Whites, ideas about the boldness and virtue of doing IQ science, and claims of White innocence about the effects of prejudice. A good deal of time and intelligence has been invested in the exposure of racism and the horrific results on its objects. But that well-established study should be joined with another, equally important one: the impact of racism on those who perpetuate it . . . to see what racial ideology does to the mind, imagination, and behavior of masters. (Morrison, 1992, pp. 11-12) INTRODUCTION This article examines certain claims about superior White intelligence using an emerging perspective in the study of racial relations that we have previously advocated (Feagin & Vera, 1995). Our perspective focuses on the symbolic labor that Whites use to construct a psychological and cultural self that helps to legitimize White power and privilege. Specifically, we examine what we call the sincere fictions of the White self used by Carl Brigham in A Study of American Intelligence (1923) and Richard Herrnstein and Charles Murray in The Bell Curve (1994). Both books were published in the midst of congressional debates on racial/ethnic issues of critical national importance and both sought to influence the outcome of these debates. Both claimed a scientific status for their ideas. Brigham's notions of the racial and intellectual inferiority of Slavic Americans, Irish Americans, Mediterranean-area Americans, and African Americans gave ammunition to those pressing for passage of the 1924 Immigration Restriction Act, an openly racist law that heavily favored immigration of northern and western Europeans and excluded or restricted the immigration of those considered to be lesser races. More recently, Herrnstein and Murray's book not only defends the genetic basis of differences in intelligence test scores between Blacks and Whites but also attacks affirmative action and defends anti-immigration sentiment. Not coincidentally, this ideological book appeared at a time when congressional actions were increasingly focused on restricting immigration, cutting back affirmative action programs, and eviscerating many welfare programs, an agenda made clear in the Republican Party's Contract with America that emerged after the 1994 elections. In between the publication of these two works, many similar books and lengthy articles proposing a genetic explanation for observed racial differences in intelligence test scores were published. These include the books and articles of Audrey M. Shuey (1958), a southern social scientist; Arthur Jensen (1969), a University of California-Berkeley educational psychologist; and William Shockley (1965), a Nobel prize-winning physical scientist. All of these works have been found repeatedly to be plagued by conceptual and methodological errors (Gould, 1981). Significantly, the latest volume in an old tradition of defending intelligence differences between racial and ethnic groups, The Bell Curve, offers little new in its arguments. It is simply the latest installment in the long history of pseudo-scientific racism in the United States. Although over 70 years separate A Study of American Intelligence from The Bell Curve, there is much similarity in their outlooks and arguments. This suggests how persistent and fundamental to the White self-concept in the United States are claims of superior White intelligence. …

Birth weight and intellectual performance in late adolescence

The impact of birth weight on cognitive performance in late adolescence was assessed in a study of 20,567 male infants born in Jerusalem between 1964-1970. The 17-year follow-up was performed by matching computerized data base records. Stepwise multiple regression analysis was used to estimate the effect of birth weight on intelligence test scores, adjusting for the influence of ethnic origin, maternal and paternal education, social class (determined by area of residence), maternal age, and birth order. These confounders explained 22% of the variance in intelligence test scores. The adjusted differences in intelligence test scores were significantly lower for groups with birth weight less than 2000 g (-6.5 points), 2000-2499 g (-3.6 points), and 2500-2999 g (-1.6 points) compared with the group weighing 3000-3499 g. Most low birth weight infants achieved intellectual performance within the normal range. However, despite this reassuring finding, low weight at birth in male subjects was found to have a statistically significant independent association with inferior intelligence test achievements in late adolescence.

A Critique of“A Simple Exposition of Jensen’s Error”

Milkman (1978) accuses Arthur Jensen of misapplying heritability data in speculating on the causes of racial differences in intelligence test scores. He then offers a method for illuminating Jensen’s alleged “error”. It is contended in this article that Milkman (1978) has misconstrued Jensen’s (1973) argument and that, as a consequence, his method is without point.

A Six Year Study of Children Who Learned to Read in School at the Age of Four

REPORTS THE READING ACHIEVEMENT during grades 1-4 of children who participated in a 2-year, pre-first grade language arts program. It also compares their achievement with that of classmates who did not participate in the program but who had attended kindergartens in which some attention went to numeral and letter naming and to the development of a small reading vocabulary. For each of the 4 years, the reading achievement of experimental subjects exceeded that of the control group. With reading test raw scores as the experimental variable and intelligence-test raw scores as the covariate, an analysis of covariance indicated that the differences in grades 1 and 2 were large enough to be significant beyond the .05 level. In grades 3 and 4, this was not the case. For both experimental and control groups, correlation coefficients for reading achievement and chronological age were always small and non-significant. T-tests indicated that differences in intelligence test scores for the 2 groups of subjects were also non-significant.

THE CORRELATION BETWEEN MENTAL AND PHYSICAL GROWTH IN TWINS

Summary. The intra pair differences in intelligence test scores and measures of physique were correlated for two samples of twins. In both the correlation coefficients so obtained were not significantly different from zero. The method of correlating intra pair differences is equivalent to holding socio‐economic differences constant, as each pair of twins has the same socio‐economic environment. The findings of this inquiry are compatible with the hypothesis that the observed correlations between measures of intelligence and physique, which are positive and greater than zero, are due to common environmental influences, and that there is no biological correlation between mental and physical growth.

Sex Differences in Intelligence-Test Scores in the Elementary School

The outcome of any intelligence test may be regarded as con ditioned by a series of factors, such as age, sex, native ability, school training, practice, and race. Of these factors, comparatively little attention has been paid to sex, perhaps because the sex difference was regarded as of little magnitude or of little practical import. In the classifications of pupils, for example, the scores of either sex have been, doubtless quite properly, compared with the single standard score for the age or grade in question, which has been itself derived from the scores obtained by hundreds of children of both sexes combined, to furnish the standard age score or the standard grade score. Most investigators, however, have been aware of the existence of a small sex difference, and this difference has at least an aca demic interest when it is considered in its possible theoretical rela tions to the rate of physical and mental maturity of the two sexes during childhood and adolescence. Moreover, it possesses still greater interest when the direction of the sex difference is discovered to be reversed in the secondary school. It seems worth while, there fore, to assemble pertinent facts concerning the sex differences in elementary-school scores and then to compare this situation with that revealed in the high school. In this paper, accordingly, I shall present facts concerning two well-known intelligence tests designed for elementary-school use, namely, the National Intelli gence Test, Scale A, and the Illinois General Intelligence Scale. Subsequently, I shall present facts concerning sex differences dis covered by the use of Army Alpha in the high school.