Timothy C. Bates

Happiness Is a Personal(ity) Thing The Genetics of Personality and Well-Being in a Representative Sample

Subjective well-being is known to be related to personality traits. However, to date, nobody has examined whether personality and subjective well-being share a common genetic structure. We used a representative sample of 973 twin pairs to test the hypothesis that heritable differences in subjective well-being are entirely accounted for by the genetic architecture of the Five-Factor Models personality domains. Results supported this model. Subjective well-being was accounted for by unique genetic influences from Neuroticism, Extraversion, and Conscientiousness, and by a common genetic factor that influenced all five personality domains in the directions of low Neuroticism and high Extraversion, Openness, Agree-ableness, and Conscientiousness. These findings indicate that subjective well-being is linked to personality by common genes and that personality may form an “affective reserve” relevant to set-point maintenance and changes in set point over time.

Genetics of intelligence

This article provides an overview of the biometric and molecular genetic studies of human psychometric intelligence. In the biometric research, special attention is given to the environmental and genetic contributions to specific and general cognitive ability differences, and how these differ from early childhood to old age. Special mention is also made of multivariate studies that examine the genetic correlation between intelligence test scores and their correlates such as processing speed, birth weight and brain size. After an overview of candidate gene associations with intelligence test scores, there is a discussion of whole-genome linkage and association studies, the first of which have only recently appeared.

Enduring Links From Childhood Mathematics and Reading Achievement to Adult Socioeconomic Status

Understanding the determinants of socioeconomic status (SES) is an important economic and social goal. Several major influences on SES are known, yet much of the variance in SES remains unexplained. In a large, population-representative sample from the United Kingdom, we tested the effects of mathematics and reading achievement at age 7 on attained SES by age 42. Mathematics and reading ability both had substantial positive associations with adult SES, above and beyond the effects of SES at birth, and with other important factors, such as intelligence. Achievement in mathematics and reading was also significantly associated with intelligence scores, academic motivation, and duration of education. These findings suggest effects of improved early mathematics and reading on SES attainment across the life span.

Confirmatory Factor Analysis of the Three-Factor Structure of the Schizotypal Personality Questionnaire and Chapman Schizotypy Scales

We examined the factor structure of the Schizotypal Personality Questionnaire (SPQ; Raine, 1991), using confirmatory factor analysis in 3 experiments, with an aim to better understand the construct of schizotypy. In Experiment 1 we tested the fit of 2-, 3-, and 4-factor models on SPQ data from a normal sample. The paranoid 4-factor model fit the data best but not adequately. Based on the strong basis for the Raine 3-factor model we attempted to improve the fit of the 3-factor model by making 3 modifications to the Raine model. These modifications produced a well-fitting model. In Experiment 2 the good fit of this modified 2-factor model to SPQ scores was replicated in an independent normal sample. In Experiment 3, the modified 3-factor model was successfully extended to include the 3 Chapman schizotypy scales. Together these 3 experiments indicate that the 3-factor model of the SPQ, albeit with some slight modifications, is a good model for schizotypy structure that is not restricted to 1 measure of schizotypal personality traits.

A Haplotype Spanning KIAA0319 and TTRAP Is Associated with Normal Variation in Reading and Spelling Ability

BACKGROUND KIAA0319 (6p22.2) has recently been implicated as a susceptibility gene for dyslexia. We aimed to find further support for this gene by examining its association with reading and spelling ability in adolescent twins and their siblings unselected for dyslexia. METHODS Ten single nucleotide polymorphisms (SNPs) in or near the KIAA0319 gene were typed in 440 families with up to five offspring who had been tested on reading and spelling tasks. Family-based association analyses were performed, including a univariate analysis of the principal component reading and spelling score derived from the Components of Reading Examination (CORE) test battery and a bivariate analysis of whole-word reading tests measured in a slightly larger sample. RESULTS Significant association with rs2143340 (TTRAP) and rs6935076 (KIAA0319) and with a three-SNP haplotype spanning KIAA0319 and TTRAP was observed. The association with rs2143340 was found in both analyses, although the effect was in the opposite direction to that previously reported. The effect of rs6935076 on the principal component was in the same direction as past findings. Two of the three significant individual haplotypes showed effects in the opposite direction to the two prior reports. CONCLUSIONS These results suggest that a multilocus effect in or near KIAA0319 may influence variation in reading ability.

Dyslexia and DCDC2: Normal variation in reading and spelling is associated with DCDC2 polymorphisms in an Australian population sample

The 6p21-p22 chromosomal region has been identified as a developmental dyslexia locus both in linkage and association studies, the latter generating evidence for the doublecortin domain containing 2 (DCDC2) as a candidate gene at this locus (and also for KIAA0319). Here, we report an association between DCDC2 and reading and spelling ability in 522 families of adolescent twins unselected for reading impairment. Family-based association was conducted on 21 single nucleotide polymorphisms (SNPs) in DCDC2 using quantitative measures of lexical processing (irregular-word reading), phonological decoding (non-word reading) and spelling-based measures of dyslexia derived from the Components of Reading Examination test. Significant support for association was found for rs1419228 with regular-word reading and spelling (P=0.002) as well as irregular-word reading (P=0.004), whereas rs1091047 was significantly associated (P=0.003) with irregular-word reading (a measure of lexical storage). Four additional SNPs (rs9467075, rs9467076, rs7765678 and rs6922023) were nominally associated with reading and spelling. This study provides support for DCDC2 as a risk gene for reading disorder, and suggests that this risk factor acts on normally varying reading skill in the general population.

John Marshall and the developmental dyslexias

Background: In 1984, John Marshall made the case that one can use a model of the skilled reading system not only to interpret the acquired dyslexias, but also to interpret the developmental dyslexias, and the particular model of the skilled reading system he favoured for this purpose was the dual-route model. This claim has been a controversial one, with many researchers claiming that static models of adult skilled reading, such as the dual-route model, are inappropriate for understanding the process of reading development and, consequently, the developmental reading disorders. Aims: In this paper, we examine how Marshalls conjecture has fared over the past 20 years. Main Contribution: We evaluate Marshalls conjecture by examining evidence for developmental analogues of acquired surface and phonological dyslexia, by reporting new data on cases of “pure” developmental surface and phonological dyslexia, and by assessing the success of dual route versus connectionist accounts of these subtypes. We also report evidence that the dual-route model of skilled reading provides an accurate account of the reading performance of children at all stages of reading development. Conclusion: We conclude that Marshalls controversial claim has been vindicated by subsequent research.

Music and spatial IQ

Abstract Rauscher, Shaw and Ky (1993) have reported a significant and relatively large improvement in spatial IQ scores (up to eight points) after listening to Mozarts Sonata for two pianos in D major (K488) compared to either silence or relaxation music. This result if replicated may have considerable implications for improving spatial intelligence in educational and organizational settings. In order to replicate this relationship, 30 subjects participated in an experiment in which the effect of music (Mozart, popular dance music or silence) was measured on Raven Advanced Progressive Matrices scores. No significant effect of music on IQ performance was found.

Dyslexia and DYX1C1: deficits in reading and spelling associated with a missense mutation.

The status of DYX1C1 (C15q21.3) as a susceptibility gene for dyslexia is unclear. We report the association of this gene with reading and spelling ability in a sample of adolescent twins and their siblings. Family-based association analyses were carried out on 13 single-nucleotide polymorphisms (SNPs) in DYX1C1, typed in 790 families with up to 5 offspring and tested on 6 validated measures of lexical processing (irregular word) and grapheme–phoneme decoding (pseudo-word) reading- and spelling-based measures of dyslexia, as well as a short-term memory measure. Significant association was observed at the misssense mutation rs17819126 for all reading measures and for spelling of lexical processing words, and at rs3743204 for both irregular and nonword reading. Verbal short-term memory was associated with rs685935. Support for association was not found at rs3743205 and rs61761345 as previously reported by Taipale et al., but these SNPs had very low (0.002 for rs3743205) minor allele frequencies in this sample. These results suggest that DYX1C1 influences reading and spelling ability with additional effects on short-term information storage or rehearsal. Missense mutation rs17819126 is a potential functional basis for the association of DYX1C1 with dyslexia.

Crystallized intelligence as a product of speed and drive for experience: the relationship of inspection time and openness to G and Gc

Abstract The five-factor model personality domain of openness (O) is theoretically independent of intelligence and thus should not correlate with information-processing speed markers of general ability (g). Simultaneously, if information-processing speed is basic to g, then computational speed should correlate not only with g but also with subsidiary facets of intelligence, such as crystallized intelligence (GC). These important relationships were explored using the inspection time (IT) measure of information-processing speed together with the O scale of the NEO-PI R (Costa & McCrae, 1995) and separate psychometric tests of g (Ravens Matrices) and GC (vocabulary and comprehension). Ravens and the Gc measure correlated .598, while IT correlated with both Ravens (r=−.558) and GC (r=−.401) supporting a basic role of computational speed in g. O correlated significantly with GC (r=.338), but not with Ravens nor with IT. Structural equation modeling supported two models in which O was independent of g, with IT being basic to g, and with GC reflecting the joint action of g and O. Paths from O to IT or to Ravens were not significant, suggesting that any apparent relationship of O to intelligence is due not to effects of O on ability, but rather to the effects of O on interest in knowledge, a joint final path with ability.