DNA markers associated with general and specific cognitive abilities

Multivariate quantitative genetic research suggests a hierarchical model of cognitive abilities where genetic effects are largely general, cutting across most cognitive abilities. Some genetic effects, however, are specific to certain cognitive abilities. These results lead to a hypothesis for molecular genetic research: Although most genes associated with one cognitive ability will be related to other cognitive abilities, some genes will be specific to a particular cognitive ability. The current research explored this hypothesis in an analysis of data in specific cognitive abilities from 86 children from 6 to 12 years of age from a larger allelic association study of general cognitive ability. Eight DNA markers were entered simultaneously in separate multiple regression analyses predicting each of four specific cognitive ability factors (Verbal, Spatial, Perceptual Speed, Memory), as well as WISC-R subtest scores. Four marjers (CTGB33, EST00083, HLA, and SOD2) showed similar effects across the cognitive ability scales, suggesting that they are related to general cognitive ability (g). These associations became negligible when the effects of ‘g’ (WISC-R IQ) were removed. Three markers (ADH5, DM, and NGFB) continued to be significantly associated with specific cognitive ability scales after the effects of ‘g’ were removed. Although preliminary, these molecular genetic results support the hierarchical model predicted by quantitative genetic research.     

Parents Think Their Sons Are Brighter Than Their Daughters: Sex Differences in Parental Self-Estimations and Estimations of Their Children's Multiple Intelligences

In this study, 156 participants, predominantly White British adults (M age = 44.3 years) rated themselves on overall IQ and on H. Gardner's (1983) 7 intelligence subtypes. Parents (n = 120) also estimated the intelligence of their children. Men's self-estimates were significantly higher than women's (110.15 vs. 104.84). Participants thought their verbal, mathematical, and spatial intelligence scores were the best indicators of their own overall intelligence. Parents estimated that their sons had significantly higher IQs than their daughters (115.21 vs. 107.49). Self-estimates and estimates of children's multiple intelligences were higher for men and sons, significantly so for logical-mathematical and spatial intelligence. Parents rated 2nd-born daughters as having significantly higher verbal and musical intelligence than their male counterparts. Higher parental IQ self-estimates corresponded with higher IQ estimates for children. Results for 1st-born children were clearest and showed the most significant differences. The findings are interpreted in terms of sociocultural and familial influences and the possibility of actual sex differences in particular abilities.     

Failure to replicate a QTL association between a DNA marker identified by EST00083 and IQ

In a paper published in this journal, a possible QTL association was reported between general cognitive ability and a marker, identified by an expressed sequence tag, EST00083 (Skuder et al., 1995). In two small samples, the frequency of the common allele of this DNA marker, which was shown to be in the threonine transfer RNA gene in mitochondrial DNA, was significantly greater in a high-IQ group than in a low-IQ group. As part of the ongoing IQ QTL Project (Plomin et al., 1995), we have attempted to replicate this QTL association. First, we found that the QTL association remained significant when we compared 51 high- and 51 -average IQ subjects, drawn in part from the samples used in the previous report. However, when we examined the association in new samples of 40 extremely high-IQ subjects and 50 average-IQ subjects, the association did not replicate. This underlies the need for replication in case-control studies of allelic association.     

Psychometrics of a simple method for scoring organizational approach on the Rey‐Osterrieth complex figure

The Rey‐Osterrieth Complex Figure (ROCF) is a commonly used neuropsychological measure that assesses visuospatial processing, planning and visuomotor integration. Using samples of clinically referred (N=20) and non‐clinical (N=44) adults, the present study examines the psychometric properties of a simple method of scoring organizational approach to the ROCF. Developed by Savage et al. (1999) and refined by Deckersbach et al. (2000) , this simple 5‐point organizational scoring system allows for the quick and accurate assessment of organizational quality. Results suggest that this system is internally consistent and can be scored reliably. Correlations with measures of visuomotor integration and accuracy of rendition after a delay provide evidence of convergent validity. Organization scores were independent of both Verbal and Performance IQ estimates. However, discriminant validity analyses found that high‐functioning patients referred for a neuropsychological assessment did not score significantly different from a non‐clinical sample, raising questions about the diagnostic utility of this measure with less impaired populations. Implications for clinical practice are discussed, as are directions for future research.     

Intelligence and Creativity: Over the Threshold Together?

Threshold theory predicts a positive correlation between IQ and creativity scores up to an IQ level of 120 and no correlation above this threshold. Primary school children were tested at beginning (N = 98) and ending (N = 70) of the school year. Participants performed the standard progressive matrices (SPM) and the Test of Creative Thinking—Drawing Production (TCT-DP). Each child with IQ ≥ 120 was grade-and-gender matched to a child with IQ < 120. Results in accordance with the threshold theory were found only for female children in the highest grade level (Grade 4). Longitudinal analysis implies that a subgroup of children goes down in IQ and creativity simultaneously, possibly due to motivational issues. Their correlated scores may be a source of evidence for the threshold theory. The relationship between intelligence and creativity is not straightforward and depends on a combination of factors including grade level and gender.     

Lasting Effects of Alcohol on the Reduction of Anxiety in Rats

A factor analysis was performed combining HSPQ forms A and B scores from a group of high school males (N = 1504) and a group of high school females (N + 1255). Eight factors were extracted and rotated from each of the two groups. It was found that the resulting factor patterns were both clearer (had better simple structure) and more closely matched the second order factor structure found among adults than previous HSPQ structures. These results supported the contention that (a) there are comparable second order personality factors between adults and high school students, and (b) since the factor pattern was similar to patterns found previously, the primary factors tend to be stable.     

Physical attractiveness and academic performance: Beauty is not always talent1

Stepwise multiple regressions were used to determine the relative importance of physical attractiveness in the prediction of academic achievement for two samples of college students. In the first study, only ACT scores made an independent contribution to the prediction of males' (N= 55) grade average. For females (N= 65), verbal IQ (as measured by Borgatta and Corsini's Quick Word Test) and father's education yielded the only independent effects. In the second, follow-up study, males' (N= 50) achievement was significantly positively associated with intelligence and high school grades and negatively associated with attractiveness. For females (N= 87), independent effects were obtained for intelligence, high school grades, socio-economic status (positively correlated), and need for approval (negatively correlated). Attractiveness was again not associated with females' academic performance. In a final study involving high school students, attractiveness was not associated with achievement for 84 boys but was negatively associated for 83 girls. The results are discussed in terms of potential underlying mechanisms and the limitations of a “what is beautiful is good” stereotype.     

Personality Profiles of Homosexual Men and Women

There has been surprisingly little research on possible differences between homosexual and heterosexual personalities, although the few studies that have been conducted suggest some interesting differences. We devised two hypothesis that may account for these differences. First, differences appear to reflect generalized social nonconformity and alienation due to the social stigmatization of the homosexual. Second, these differences seem to express a more specific tendency to deviation from socially normative sex roles. The two hypotheses imply a number of predictions concerning specific personality traits, which were tested by comparing the 16PF (Cattell, Eber, & Tatsuoka, 1970) personality profiles of a group of male (N = 34) and female (N = 31) homosexuals with those obtained from the two large student samples (male, N = 899 and female, N = 912) whose scores are commonly used as norms for the South African version of the 16PF. The findings suggested reasonably good support for the two hypotheses, particularly considering the limitations of the study with respect to the adequacy of the comparison groups used and the relative heterogeneity of the 16PF scale content.     

Effects of Race,Class, and IQ Information on Judgments of Parochial Grade School Teachers

Abstract

Parochial grade school teachers (N = 80) evaluated pictures of two boys previously identified as Hispanic lower class, Hispanic middle class, White lower class, and White middle class based on physical appearance. Initially, race and social class affected teacher judgments. After receiving information about IQ, the teachers reevaluated the pictures. Social class was no longer a factor, but race still influenced teacher judgments to the extent that the high IQ Hispanic child, regardless of perceived social class, was evaluated less positively than the high IQ White child. From the teachers' comments, it was concluded that these teachers believed that their biases were reliable predictors of future success.     

Skull size and intelligence, and King Robert Bruce's IQ

An estimate of someone's IQ is a potentially informative personal datum. This study examines the association between external skull measurements and IQ scores, and uses the resulting regression equation to provide an estimate of the IQ of King Robert I of Scotland (Robert Bruce, 1274–1329). Participants were 48 relatively healthy Caucasian men (age 71–76 years) resident in Scotland. Using magnetic resonance imaging data, intracranial volume estimated from external skull length and width correlated greater than .5 (p < .001) with measured intracranial area, which correlates very highly with brain volume. IQ scores estimated from the National Adult Reading Test (NART) correlated .56 (p < .001) with measured intracranial area, and .49 (p < .01) with estimated intracranial volume based on external skull width and length. The partial correlation coefficient of this latter association was .25 (p = .09) after adjustment for measured intracranial area. Thus, actual intracranial area accounts for about 74% of the variance shared by NART and estimated intracranial volume. A cast of the skull of Robert Bruce was measured and its intracranial volume estimated. A regression equation between IQ and estimated intracranial volume, based on data from the 48 subjects, estimated the IQ of Robert Bruce at about 128 (95% confidence interval 106 to  130), i.e. almost two standard deviations above the mean. NART scores show a ceiling effect, so this estimated IQ might be an underestimate. Robert Bruce's estimated high IQ is congruent with his military, political and other intellectual achievements.     

Meta-analysis of the relationship between intelligence and inspection time

This study replicated and extended Kranzler and Jensen's [Intelligence 13 (1989) 329] meta-analysis of the relationship between inspection time (IT) and intelligence (IQ). Separate meta-analyses were conducted on obtained correlations (r's) between IT and general IQ for the total sample and for studies using samples of adults and children. Two new meta-analyses were also conducted. The first compared the IT–IQ r between visual and auditory IT; the second compared the r between strategy users and nonusers. For the total sample (N>4100), the r was −.51 after correction for artifactual effects (−.30 prior to correction). No statistically significant difference was observed between the mean corrected r of −.51 for adults and −.44 for children. The mean corrected r for visual and auditory IT measures were −.49 and −.58, respectively, suggesting that the relationship between IT and IQ is comparable across type of IT task. The mean corrected r of −.77 for strategy nonusers was statistically significantly higher than the r of −.60 for strategy users. Implications of these findings for future research are discussed.     

Opinion leadership types or continuous opinion leadership traits?

Opinion leadership is typically conceptualised as a continuous personality trait. However, many authors adhere to the view of qualitatively different opinion leadership types and apply arbitrary criteria to split continuous trait scores into two groups (i.e., opinion leaders vs. non‐leaders). The present study is the first to empirically evaluate this approach. A sample of N = 3812 adults (67% women) was administered a validated opinion leadership scale. Finite mixture models examined whether the latent trait distribution can be represented by a set of discrete trait levels that reflected distinct opinion leadership types. The results did not give support to a discrete typology that distinguished leaders from non‐leaders. Rather, opinion leadership was best characterised as a continuous trait.     

A Quantitative Trait Locus Associated With Cognitive Ability in Children

Quantitative trait loci (QTLs) associated with general cognitive ability ( g ) were investigated for several groups of children selected for very high or for average cognitive functioning. A DNA marker in the gene for insulin-like growth factor-2 receptor (IGF2R) on Chromosome 6 yielded a significantly greater frequency of a particular form of the gene (allele) in a high- g group (.303; average IQ = 136, N = 51) than in a control group (.156; average IQ = 103, N = 51). This association was replicated in an extremely-high- g group (all estimated IQs > 160, N = 52) as compared with an independent control group (average IQ = 101, N = 50), with allelic frequencies of .340 and .169, respectively. Moreover, a high-mathematics-ability group ( N = 62) and a high-verbal-ability group ( N = 51) yielded results that were in the same direction but only marginally significant ( p = .06 and .08, respectively).     

Temperament and its Relationship to Autistic Symptoms in a High-Risk Infant Sib Cohort

The present study prospectively investigated early temperamental profiles and their associations with autistic symptoms in high-risk infants (N = 138) with an older sibling with autistic spectrum disorder (ASD) and low-risk infants (N = 73) with no family history of ASD. Children who were diagnosed with ASD at 36 months were distinguished from non-ASD sibs and controls by a temperament profile marked by lower positive affect, higher negative affect and difficulty controlling attention and behavior, which we labeled Effortful Emotion Regulation. This profile also distinguished the non-ASD sib group from the control group. Children with ASD were distinguished from both of the other two groups by a temperament profile of low Behavioral Approach (lower sensitivity to “social” reward cues). Low levels of Behavioral Approach were associated with a higher number of ASD symptoms, even after taking into account IQ, sex and group membership. Finally, a cluster analysis revealed two ASD subgroups distinguished by number of ASD symptoms, IQ, age of diagnosis and scores on the Behavioral Approach profile. These findings suggest that temperament may be a useful framework for understanding the emergence of ASD early in life.     

Assessing State Mental Contamination: Development and Preliminary Validation of the State Mental Contamination Scale

This 2-part study described the development and preliminary validation of the State Mental Contamination Scale (SMCS), a multi-item self-report measure of state mental contamination. In Study 1, community adults (N = 211) in the United States were randomly assigned to a pathogen disgust, moral disgust, or neutral condition and then completed the SMCS. Study 1 results supported a 1-factor structure of the SMCS items. Scores on the SMCS items evidenced good internal consistency and strong interitem correlations. SMCS scores were significantly greater following the 2 disgust conditions relative to the neutral condition and a full range of SMCS scores were found in the disgust conditions. An independent sample of community adults (N = 121) from the United States participated in Study 2 to extend Study 1 results. Study 2 results indicated that SMCS scores were manipulated independently of trait mental contamination, more strongly related to convergent than a discriminant measure, and shared unique variance with a criterion measure after controlling for convergent measures. The future use of the SMCS is discussed.     

The Relationship Between Diverse Components of Intelligence and Creativity

Intelligence and creativity are accounted for in terms of two different mental operations referred to as ‘convergent thinking’ and ‘divergent thinking’, respectively. Nevertheless, psychometric evidence on the relationship between intelligence and creativity has been controversial. To clarify their relationship, we characterized the relationship between diverse components of intelligence and creativity through the administration of psychometric tests on a large sample (WAIS, RPM, and TTCT‐figural: n = 215; TTCT‐verbal: n = 137). The general intelligence factor (g) score showed significant correlations with both TTCT‐figural and TTCT‐verbal scores. However, sub‐dimensional analysis demonstrated that their association was attributable to the specific components of both TTCTs (TTCT‐figural: Abstractness of Titles, Elaboration, and Resistance to Premature Closure; TTCT‐verbal: Flexibility) rather than to their common components (Fluency and Originality). Among the intelligence sub‐dimensions, crystallized intelligence (gC) played a pivotal role in the association between g and the specific components of both TTCTs. When the total sample was divided into two IQ groups, these phenomena were more evident in the average IQ group than in the high IQ group. These results suggest that the mental operation of creativity may be different from that of intelligence, but gC may be used as a resource for the mental operation of creativity.     

Tailoring the Mode of Information Presentation: Effects on Younger and Older Adults' Attention and Recall of Online Information

Previous studies have mainly focused on tailoring message content to match individual characteristics and preferences. This study investigates the effect of a website tailored to individual preferences for the mode of information presentation, compared to 4 nontailored websites on younger and older adults' attention and recall of information, employing a 5 (condition: tailored vs. text, text with illustrations, audiovisual, combination) × 2 (age: younger [25–45] vs. older [≥65] adults) design (N = 559). The mode‐tailored condition (relative to nontailored conditions) improved attention to the website and, consequently, recall in older adults, but not in younger adults. Younger adults recalled more from nontailored information such as text only or text with illustrations, relative to tailored information.