Black–White differences on the g-factor in South Africa: a “Jensen Effect” on the Wechsler Intelligence Scale for Children — revised

A test is made to determine whether South African Black–White differences on various tests of cognitive performance are like the Black–White differences in the United States in being positively associated with a test's g loadings, where g is the general factor of intelligence. Data are analyzed from Skuy, Schutte, Fridjhon and O'Carroll [Skuy, M., Schutte, E., Fridjhon, P., & O'Carroll, S. (2001). Suitability of published neuropsychological test norms for urban African secondary school strudents in South Africa. Personality and Individual Differences, 30, 1413–1425) of 154 13- to 15-year-old secondary school students in Soweto, Johannesburg, on the Wechsler Intelligence Scale for Children–Revised (WISC-R). The more highly correlated a sub-test was with g, the more it predicted the African–White difference (r =0.77, p=0.05). The effect remained even when the Vocabulary sub-test was excluded or when g was extracted from the Black rather than from the White standardization sample (r=0.60, P<0.05), as it did as well if Spearman's rho was used instead of Pearson's r (g from Whites=0.74, g from Blacks=0.74, P< 0.005). Understanding observed Black–White differences around the world requires new research on the nature and nurture of g.     

Which factors best account for academic success: Those which college students can control or those they cannot?

This study integrates research linking academic performance with individual differences and class attendance. Whereas individual differences (ability, traits) are not controllable by students, students can control their attendance, study and work. Thus we sought to determine the extent to which “control” and “no control” variables predict academic performance. With N = 338, measures of verbal ability, the five-factor model, GPA, academic goals, and study behavior were used to predict exams, attendance, and independent projects completed. Uncontrollable factors accounted for 37% of the variance in exam scores; controllable factors accounted for an additional 6–10%. We also found an interaction such that, relative to low-ability peers, high-ability students’ attendance most enhanced their exam performance. Attendance was best accounted for by GPA, study and work. Projects were best predicted by low verbal ability and by personality traits.     

Black–White mean differences in job satisfaction: A meta-analysis

Studies examining Black–White mean differences in job satisfaction have provided little clarity regarding whether there are meaningful differences between the two racial/ethnic groups on this job attitude. The present study sought to reconcile prior inconsistent findings via a meta-analytic synthesis of this literature (N = 753,791; K = 63 independent samples from 55 studies) and examined whether moderators explained the observed variability in effects. Using Hedges and Vevea's (1998) random-effects meta-analytic approach, we found that, on average, White workers were slightly more satisfied with their jobs than Black workers (g_corrected = .09; 95% credibility interval = −.21 to .39) and this effect was larger in more nationally representative samples (g_corrected = .24). The substantial true variability around this effect suggests the presence of moderators and the need for caution in interpreting the overall effect as it likely does not generalize across all work settings. Data collection year, geographic location within the U.S., job sector, and measure type were not found to moderate Black–White mean differences in job satisfaction. However, job complexity and sample demographic composition did significantly moderate this relationship. Our results show that the magnitude and direction of Black–White mean differences in job satisfaction are influenced by the context.     

Performance on Raven's Matrices by African and White University Students in South Africa

Untimed Raven's Standard Progressive Matrices (SPM) were administered to 309 17- to 23-year-old students at the University of the Witwatersrand and the Rand Afrikaans University in Johannesburg, South Africa (173 Africans, 136 Whites; 205 women, 104 men). African students solved an average of 44 of the 60 problems whereas White students solved an average of 54 of the problems (p<.001). By the standards of the 1993 US normative sample, the African university students scored at the 14th percentile and the White university students scored at the 61st percentile (IQ equivalents of 84 and 104, respectively). The African–White differences were found to be greater on those items of the SPM with the highest item–total correlations, indicating a difference in g, or the general factor of intelligence. A small sex difference favoring males was found in both the African and the White samples, but unrelated to g.     

Dispositional happiness and college student GPA: Unpacking a null relation

We examined the mechanisms that underlie the null relation between dispositional happiness and college grade point average (GPA) by testing the hypothesis that dispositional happiness has positive and negative indirect links to GPA that offset each other. The sample consisted of 317 first-year students. Using structural equation modeling, we found that dispositional happiness exerted a positive indirect effect on cumulative GPA via commitment to college (p < .01) and a negative indirect effect on cumulative GPA via satisfaction with peer (student) relationships (p < .05). As predicted, the sum of its indirect effects on cumulative GPA was not significant (p = .22).     

Jensen Effects and African/Coloured/Indian/White differences on Raven's Standard Progressive Matrices in South Africa

A test is made to determine whether various ethnic group differences on tests of cognitive performance in South Africa are like the Black/White differences in the United States in being positively associated with a tests' g loadings, where g is the general factor of intelligence. A non-parametric re-analysis is made of data from 1056 White, 1063 Indian, 778 mixed-race “Coloured,” and 1093 Black 14 year olds on the Raven's Standard Progressive Matrices Test in South Africa, given without time limits by Owen (1992) [Personality and Individual Differences, 13, 149]. The new analyses showed that the more highly correlated an item was with g, the more it predicted the White/Indian/Coloured/African differences on the test (Spearman's rhos from 0.35 to 0.85; all Ps<0.01). The effects remained regardless of which group g was extracted from. Understanding group differences around the world requires new research on the nature and nurture of g.     

Rushton’s contributions to the study of mental ability

This essay describes Rushton’s contribution to examining the nexus of intelligence, race, and genetics, specifically what I termed “Spearman’s hypothesis”. It states that Black–White differences are “most marked in just those [tests] which are known to be saturated with g”. I (Jensen) had confirmed this hypothesis using large data sets in the 1970s and 1980s and also found that Black–White differences were most marked on the more heritable rather than the more cultural subtests. Rushton confirmed and extended these findings in many highly innovative ways and demonstrated Spearman’s hypothesis applied among samples of Gypsy Roma in Serbia, and East Asian, European, South Asian, Colored and Black samples in South Africa. He has not only documented group differences in brain size, intelligence, life span, family structure, infant mortality, developmental precocity, personality, and temperament, and rates of two egg twinning, and crime among East Asians, Europeans, and Africans, but also provided a life history theory that explains them.     

Associations among bullying role behaviors and academic performance over the course of an academic year for boys and girls

Although some research has evidenced a negative association between involvement in bullying and academic performance, more work is needed to understand the associations between academic performance and involvement in a more comprehensive range of bully role behaviors. The goals of the current study were to determine (a) the associations among a broader range of bully role behaviors (i.e., bullying, assisting, victimization, defending, and outsider behavior) and academic performance (i.e., grade point average; GPA), and (b) gender differences within these associations. The current study investigated these issues over the course of an academic year with 7794 students in middle through high school. Bullying behaviors were assessed in the fall and GPA data were gathered from school records from the spring of the same academic year. The results identified significant negative associations between bullying (b = −0.07, p = .001), assisting (b = −0.16, p < .001), victimization (b = −0.06, p < .001), and defending (b = −0.04, p < .001) with student GPA, whereas no significant association emerged for outsider behavior and GPA (b = −0.02, p = .13). In addition, several gender differences were found in these associations, including a stronger negative association between assisting and GPA for girls (b = −0.23, p = .001) than for boys (b = −0.08, p = .014) and a significant negative association between victimization and GPA for girls (b = −0.09, p < .001), but not boys (b = −0.02, p = .117). Differences in results across schools were also examined in an exploratory manner. The educational impact associated with bullying behaviors, limitations of the current study, and suggestions for future research are discussed.     

School achievement strongly predicts midlife IQ

The relationship between measures of IQ and standardized school achievement tests is well established at around r ≈ 0.5 when the two are measured in close proximity. The current paper examined the stability of this correlation when comparing elementary school achievement (grades 3–8) and midlife IQ. Iowa Adoption Study participants who had standardized school achievement measures (ITBS) on file were given the WAIS-III. Mean age at IQ testing was 44.01 years (SD 6.65 years). The correlation between school achievement and WAIS-III FSIQ was r = 0.64, suggesting substantial life span stability in this relationship. Furthermore, elementary school achievement was substantially correlated with occupational status and household income at midlife. These findings suggest that standardized school achievement data is a useful measure of premorbid IQ.     

Subgroup differences in situational judgment test scores: Evidence from large applicant samples

To promote diversity in organizations it is important to have accurate knowledge about subgroup differences associated with selection procedures. However, current estimates of subgroup differences in situational judgment tests (SJTs) are overwhelmingly based on range‐restricted incumbent samples that are downwardly biased. This study provides much‐needed applicant level estimates of SJT subgroup differences (N = 37,530). As a key finding, Black‐White differences (d = 0.66) were higher than in incumbent samples (d = 0.38). Overall, sex differences were small. Females scored higher for management jobs (d = ?0.13) and males scored higher for administrative jobs (d = 0.15). By analyzing applicant samples that do not suffer from range restriction, this study adds knowledge about subgroup differences in SJTs.     

Race, social class and ability patterns on the WISC-R

The national standardization sample of whites and blacks on the Wechsler Intelligence Scale for Children—Revised (WISC-R) was the basis for a detailed analysis of the psychometric nature of racial and social class differences on the original 13 subscales of the WISC-R. The profiles of subtest scores of whites and blacks were compared directly and also after the racial groups were statistically equated on Full Scale IQ (FSIQ). Under the latter condition, the races differ only very slightly, although significantly, on some of the subtests, in ways generally contrary to popular expectations. The profile of white-black differences on the WISC-R subtests is markedly different, and negatively correlated with, the profiles of social class differences within each racial group, indicating that the pattern of racial differences is not explainable in terms of the difference in the average socio-economic status (SES) of blacks and whites. A Schmid-Leiman orthogonalized hierarchical factor analysis yields virtually identical factor structures and highly congruent factor loadings on the subtests for whites and blacks. Analysis of factor scores shows that by far the largest proportion of the variance between races is attributable to the general factor (g) common to all the subtests, whereas the group factors (verbal, performance and memory) contribute only minutely to the interracial variance. Hence the white-black differences on the diverse subtests of the WISC-R, and in the Full Scale IQ, are interpreted primarily as a difference in Spearman's g, rather than as differences in the more specific factors peculiar to particular content, knowledge, acquired skills or type of test. However, some slight but significant differences in patterns of ability also occur that are independent of g.     

International comparison of Cloninger’s temperament dimensions

Cloninger’s Tridimensional Personality Questionnaire (TPQ) and Temperament and Character Inventory (TCI) have been developed to measure the following temperament dimensions: novelty seeking (NS), harm avoidance (HA), reward dependence (RD) and persistence (P). We used our previous Finnish normative study of the TPQ and TCI (Miettunen et al., 2004) to estimate correction coefficients to convert TPQ scales to comparable TCI scales. Our aim was to compare these corrected temperament dimension scores across 20 countries adjusting for study sample differences in age and gender. In all, some variations were found in these temperament scores between countries. Differences were especially apparent between the Asian and the Western countries. By far the lowest mean score of the RD was in Japan (11.2 vs. 15.4 for other countries; effect size Cohen’s d = −5.74; z-test p < 0.001) and the highest mean score in P was in USA (5.5 vs. 4.4; d = 4.24, p = 0.001). Some of the findings could be explained by sample differences (e.g. age and education); while some may reflect real differences in the ways which personality is related to cultural factors, such as individualism/collectivism. These differences should be considered when interpreting studies with data on TPQ/TCI from different countries.     

Increasing Psychological Capital: A Pre-Registered Meta-Analysis of Controlled Interventions

The aim of this meta-analysis was to evaluate the overall effectiveness of interventions designed to enhance psychological capital (PsyCap), well-being, and performance. We used inclusion criteria such as: to have an experimental design, the sample to be formed by employees or students, to contain a measure of PsyCap, and a control group. Forty-one trials (N_total = 3,911) met these criteria. The overall effect of the interventions on all PsyCap variables was significant but small (d = 0.34, k = 41, Z = 6.74, p < .001). Separate analyses on each of the PsyCap variables also revealed significant effects: small effects on developing PsyCap (d = 0.26, k = 9, Z = 4.37, p < .001), hope (d = 0.22, k = 5, Z = 2.26, p < .05), self-efficacy (d = 0.37, k = 18, Z = 4.11, p < .001), and optimism (d = 0.36, k = 12, Z = 2.52, p < .05), and a small to medium effect for resilience (d = 0.49, k = 12, Z = 3.61, p < .001). The effectiveness of the PsyCap interventions on well-being and performance is also significant.     

Do older individuals adapt to their traits?: Personality–emotion relations among younger and older adults

Prominent lifespan theories posit that older adults are motivated to engage in emotion-regulation more frequently than younger adults. The present study follows from such theories and makes a novel prediction hitherto unexamined in the aging–emotion literature. Based on the idea that older adults more frequently regulate their emotions, it was predicted that traits, reflective of temperament or habit, would be less predictive of emotions among older adults (N = 60; M age = 74.9 years) than younger adults (N = 44; M age = 19.5 years). This hypothesis was confirmed across four of the Big 5 traits and, consistent with predictions, the moderating effects of age were particularly strong for negative emotions. The discussion focuses on the implications of the present findings for understanding age differences in personality, emotion, and emotion-regulation.     

Impulsiveness and resource allocation: Testing Humphreys and Revelle’s (1984) explanation of impulsive personality

Humphreys and Revelle [Humphreys, M. S., Revelle, W. (1984). Personality, motivation and performance: A theory of the relationship between individual differences and information processing. Psychological Review, 91, 153–184] suggest that impulsive individuals have relatively greater capacity to improve performance through task-directed resource allocation. This implies that there will be a differential effect of increases in effort intensity on performance for high and low impulsive individuals. Two quasi-experiments tested this prediction using a relative-judgement task (total N = 108, 68 females), however neither revealed the predicted interaction. In light of these findings, we re-consider the Humphreys–Revelle model in relation to independent but potentially related theory and research.     

Does performance on the standard antisaccade task meet the co-familiality criterion for an endophenotype?

The “co-familiality” criterion for an endophenotype has two requirements: (1) clinically unaffected relatives as a group should show both a shift in mean performance and an increase in variance compared with controls; (2) performance scores should be heritable. Performance on the antisaccade task is one of several candidate endophenotypes for schizophrenia. In this paper we examine whether the various measures of performance on the standard version of the antisaccade task meet the co-familiality criterion for an endophenotype. The three measures of performance—reflexive saccade errors, latency of correct antisaccades, and gain—show a wide range of effect sizes and variance ratios as well as evidence of significant or near significant heterogeneity. The estimated mean effect sizes [Cohen’s d: error rate: 0.34 (SD: 0.29); latency: 0.33 (SD: 0.30); gain: 0.54 (SD: 0.38)] are significantly greater than 0, but the magnitude of the departures from 0 is relatively small, corresponding to modest effect sizes. The width of the 95% confidence intervals for the estimated effect sizes (error rate: 0.2–0.49; latency: 0.17–0.50; gain: 0.23–0.85) and the coefficients of variation in effect sizes (error rate: 85.3%; latency: 90.9%; gain: 68.4%) reflect heterogeneity in effect sizes. The effect sizes for error rate showed statistically significant heterogeneity and those for latency (P = .07) and gain (P = .09) showed a trend toward heterogeneity. These results indicate that the effect sizes are not consistent with a single mean and that the average effect size may be a biased estimate of the magnitude of differences in performance between relatives of schizophrenics and controls. Relatives of schizophrenics show a small but significant increase in variance in error rate, but the confidence interval is broad, perhaps reflecting the heterogeneity in effect size. The variance ratios for latency and gain did not differ in relatives of schizophrenics and controls. Performance, as measured by error rate, is moderately heritable. The data do not provide compelling support for a consistent shift in mean or variance in relatives of schizophrenia patients compared with nonpsychiatric controls, both of which are required for a major gene involved in co-familial transmission. This set of findings suggests that although intra-familial resemblance in antisaccade performance is due in part to genetic factors, it may not be related to a schizophrenia genotype. Based on the current literature, it would be premature to conclude that any of the measures of antisaccade performance unambiguously meets the co-familiality criterion for an endophenotype.     

Joint attention in term and preterm infants at 12 months corrected age: the significance of gender and intervention based on a randomized controlled trial

This study tested the effects of optimized neonatal mother–infant transactions on joint attention performance at 12 months. Surviving infants <2000 g from a geographically defined area were randomly assigned to a preterm intervention (n = 71) or preterm control group (n = 69). Comparisons were made between preterm groups, secondary with a term group (n = 75). Joint attention was measured using the Early Social Communication Scales. Preterm intervention infants scored significantly higher than preterm control infants on elements Initiating Joint Attention (p < 0.05), Initiating Object Requests (p < 0.05), and Responding to Social Interaction (p < 0.0005). Intervention was not associated with performance on elements Responding to Joint Attention, or on Responding to Requests. ELBW infants scored significantly lower than VLBW and LBW infants on imperative functions. Girls outperformed boys on all communication elements. An intervention implemented during the neonatal period can be of advantage for certain aspects of joint attention performance in preterm infants.     

The influence of a long term exercise program on lower limb movement variability and walking performance in patients with peripheral arterial disease

The purpose of this study was to examine the effects of a 12 month exercise program on lower limb movement variability in patients with peripheral arterial disease (PAD). Participants (n = 21) with an appropriate history of PAD and intermittent claudication (IC) volunteered for this study and were randomly allocated to either a control group (CPAD–IC) (n = 11), which received normal medical therapy and a treatment group (TPAD–IC) (n = 10), which received normal medical therapy treatment and a 12 month supervised exercise program. All participants underwent 2D joint angular kinematic analysis during normal walking to assess lower limb movement variability and walking speed. Between-group differences were analyzed via mixed measures ANOVA. The 12 month supervised exercise program made no significant impact on the lower limb movement variability or walking speed of the TPAD–IC group as determined by either intralimb joint coordination or single joint analysis techniques. Long term supervised exercise programs do not appear to influence the lower limb movement variability of PAD–IC patients.     

Motor assessment of preschool aged children: A preliminary investigation of the validity of the Bruininks–Oseretsky test of motor proficiency – Short form

The aim of this study was to examine the validity of the Bruininks–Oseretsky test of motor proficiency – short form (BOTMP-SF) [Bruininks, R. (1978). Bruininks–Oseretsky test of motor proficiency: Examiners manual. Circle Pines, MN] for the assessment of preschool aged children. Three-hundred and eighteen children 48–71 months old (M = 58.97 months, SD = 6.73) participated in the study. For the data analysis both an ANOVA and a MANOVA were applied with the total battery score and the 14 item scores being the dependent variables, respectively. Age was found to have a significant effect on both children’s total battery score (F(3, 314) = 110.65, p < .001, η² = .68) and 13 item scores (minimum F(3, 314) = 8.75, p < .001, minimum η² = .145). Although the aforementioned results represent an evidence for the validity of the BOTMP-SF, a closer study on the score of each item revealed a high percentage of zero scores on four items. Task difficulty has caused a floor effect, constituting a threat to the validity of the preschoolers’ motor assessment with the above battery. A modification of the battery items is suggested, so that the BOTMP-SF will give valid results for children 4–6 years old.