Intelligence,social class of origin,childhood behavior disturbance and education as predictors of status attainment in midlife in men: The Aberdeen Children of the 1950s study

In a birth cohort of 6281 men from Aberdeen, Scotland, social class of origin, childhood intelligence, childhood behavior disturbance and education were examined as predictors of status attainment in midlife (46 to 51 years). Social class of origin, intelligence and behavior disturbance were conceptualized as correlated predictors, whose effects were hypothesized to be partially mediated by educational qualifications. A structural equation model using Full Information Maximum Likelihood estimation confirmed that education had the strongest direct effect on status attainment at midlife. Furthermore, education partially mediated the effects of social class of origin and childhood intelligence, and fully mediated the effects of behavior disturbance on status attainment. Social class of origin, childhood intelligence and behavior disturbance were strongly inter-correlated. After controlling for these associations, educational and social status attainments were influenced to a considerably greater extent by childhood intelligence than by social class of origin.     

Bright children become enlightened adults

We examined the prospective association between general intelligence (g) at age 10 and liberal and antitraditional social attitudes at age 30 in a large (N= 7,070), representative sample of the British population born in 1970. Statistical analyses identified a general latent trait underlying attitudes that are antiracist, pro-working women, socially liberal, and trusting in the democratic political system. There was a strong association between higher g at age 10 and more liberal and antitraditional attitudes at age 30; this association was mediated partly via educational qualifications, but not at all via occupational social class. Very similar results were obtained for men and women. People in less professional occupations-and whose parents had been in less professional occupations-were less trusting of the democratic political system. This study confirms social attitudes as a major, novel field of adult human activity that is related to childhood intelligence differences.     

More intelligent, more dependable children live longer: a 55-year longitudinal study of a representative sample of the Scottish nation

The associations of childhood intelligence and dependability with adult mortality were examined in 1,181 people who were representative of the Scottish nation. Participants were born in 1936 and were followed for mortality from 1968 through early 2003. Higher intelligence and greater dependability were independent, significant predictors of lower mortality: With both factors entered together, the hazard ratio (HR) was 0.80 (95% confidence interval, CI: 0.65-0.99, p= .037) per standard deviation increase in intelligence and 0.77 (95% CI: 0.63-0.94, p= .009) per standard deviation increase in dependability. Children in the lower half of the distributions for intelligence and dependability were more than twice as likely to die compared with those who scored in the top half for both these measures (HR = 2.82; 95% CI: 1.81-4.41). Studied together for the first time in a representative sample, these two psychological variables are independent life-course risk factors for mortality. It is important to discover the mechanisms by which they influence survival.     

The origin of factor scores: Spearman,Thomson and Bartlett

The indeterminacy of factor scores has been a perennial source of debate since the time of Spearman. The main purpose of this paper is to show that, in spite of his inadequate tools and concepts, Sir Godfrey Thomson's approach of 70 years ago was on the right lines. His thinking was constrained by the primitive state of his statistical understanding but it is illuminated by his substantial exchange of the correspondence with M. S. Bartlett in the 1930s, most of which has survived in the Godfrey Thomson archive at the University of Edinburgh. In order to justify our claim and clarify the issues, we have found it necessary to fill in some of the gaps in the original derivations of Spearman, Thomson and Bartlett and to express their work in terms which are intelligible today. The opportunity is taken to relate this earlier work to contemporary debates.     

Introduction to the special issue on cognitive epidemiology

This is an introduction to a special issue of the journal Intelligence on cognitive epidemiology. Cognitive epidemiology is a new field of study, which examines the associations between intelligence—usually from early in life—and later morbidity (physical and mental) and mortality. In addition to exploring and establishing associations, studies within cognitive epidemiology attempt to explain them, by testing possible confounders and mediators, and complex pathways, of intelligence–health associations. Popular among mediators are health behaviours and education, and the well-known risk factors for chronic illnesses such as cardiovascular disease. In this special issue, readers will find advances in all of these matters. Thirteen new empirical studies, all involving large cohorts of humans, provide novel associations between intelligence and mortality, morbidity, and health behaviours and risk factors. New hypotheses of these associations are tested. This is the largest collection of cognitive epidemiology studies to date. Together, they will take the field forward by a quantum jump. This is a feast of cognitive epidemiology, establishing that, beside education and occupation, health outcomes contribute to the impressive predictive validity of intelligence differences.     

The effect of IQ level on the degree of cognitive deterioration experienced during acute hypoglycemia in normal humans

Acute hypoglycemia provokes a deterioration in cognitive function both in normal individuals and patients with Type 1 diabetes. A large interindividual variation is observed in the magnitude of the cognitive dysfunction observed during hypoglycemia, the reasons for which are not apparent. This study examines whether IQ level exerts a differential effect on the impairment of cognitive performance induced during acute hypoglycemia. Twenty-four nondiabetic participants were divided into high and average IQ groups according to their results on the Alice Heim 4 test and the National Adult Reading Test. Cognitive function was assessed during hypoglycemia using the following cognitive test battery: Paced Auditory Serial Addition Test (PASAT), Rapid Visual Information Processing (RVIP), Trail-Making B (TMB), Digit Symbol Substitution Test (DSST), and Four-Choice Reaction Time (CRT). In Condition A (the placebo condition), the participants' blood glucose was maintained at 4.5 mmol/1 throughout. On two occasions (Conditions B and C), the blood glucose was stabilized at 4.5 mmol/1 for 30 min, lowered to 2.5 mmol/1 (hypoglycemia) for 60 min, and restored to 4.5 mmol/1 for 30 min. Under each condition, the cognitive test battery was performed immediately after stabilization of blood glucose at 4.5 mmol/1, and the battery was repeated as follows: Condition A—after a further 40 min of euglycemia; Condition B—after 5 min of hypoglycemia; Condition C—after 40 min of hypoglycemia. Multivariate analysis of variance demonstrated a detoriation in cognitive performance as a result of hypoglycemia irrespective of IQ group (p< .005). Acute hypoglycemia induced a significant deterioration in cognitive function in all tests except TMB (p< .05). No overall effect of IQ on deterioration in cognitive performance could be ascertained, although univariate analysis of variance revealed an IQ effect on two of the test: The avergae IQ group deteriorated significantly less than the higher IQ group during hypoglycemia in the 4-s PASAT task (p = .03) and tended to have higher false alarm rates in the RVIP (p = .06). In conclusion, individuals with a higher IQ do not appear to be protected from tge adverse effects of acute hypoglycemia on cognitive function.     

Visual information processing and intelligence

Measures of inspection time (IT) have robust, moderately-sized correlations with IQ-type test scores. However, the reason for the IT-IQ correlation is not understood. Although the original theory asserted that IT performance was based on a single parameter—essentially speed of visual processing—peculiarities of the task have afforded other interpretations of IT differences and the IT-IQ association. In the present report two new visual processing tasks, visual change detection (VCD) and visual movement detection (VMD) are found to be correlated at or above .4 with IT and with non-verbal scores from the Alice Heim 4 test of general intelligence. VCD and VMD, in common with IT, assess the stimulus duration that is required by subjects in order to make an accurate discrimination. VCD and VMD, however, require a broader attentional focus than IT and do not involve backward masking. Measures of contrast sensitivity, a difficult discrimination task in which stimuli are not time-limited, had near-to-zero correlations with other visual processing tasks and with IQ-type test scores. We tested the hypothesis that only the latent trait derived from the speeded visual processing tasks (rather than task-specific features) would correlate with cognitive ability, and this was supported. The present study adds weight to the view that it is the ability to make accurate discriminations in the face of limited stimulus time that causes IT to correlate with psychometric intelligence. The psychological correlates of VCD, in terms of neural circuits that detect “difference” suggest a new line of investigation into the psychobiological bases of human intelligence.     

A free, easy-to-use, computer-based simple and four-choice reaction time programme: the Deary-Liewald reaction time task

Reaction time tasks are used widely in basic and applied psychology. There is a need for an easy-to-use, freely available programme that can run simple and choice reaction time tasks with no special software. We report the development of, and make available, the Deary-Liewald reaction time task. It is initially tested here on 150 participants, aged from 18 to 80, alongside another widely used reaction time device and tests of fluid and crystallised intelligence and processing speed. The new task’s parameters perform as expected with respect to age and intelligence differences. The new task’s parameters are reliable, and have very high correlations with the existing task. We also provide instructions for downloading and using the new reaction time programme, and we encourage other researchers to use it.