Sex differences in Cognitive Abilities Test scores: a UK national picture

Background and aims. There is uncertainty about the extent or even existence of sex differences in the mean and variability of reasoning test scores ( Jensen, 1998; Lynn, 1994, ; Mackintosh, 1996). This paper analyses the Cognitive Abilities Test (CAT) scores of a large and representative sample of UK pupils to determine the extent of any sex differences. Sample. A nationally representative UK sample of over 320,000 school pupils aged 11-12 years was assessed on the CAT (third edition) between September 2001 and August 2003. The CAT includes separate nationally standardized tests for verbal, quantitative, and non-verbal reasoning. The size and recency of the sample is unprecedented in research on this issue. Methods. The sheer size of the sample ensures that any sex difference will achieve statistical significance. Therefore, effect sizes (d) and variance ratios (VR) are employed to evaluate the magnitude of sex differences in mean scores and in score variability, respectively. Results. The mean verbal reasoning score for girls was 2.2 standard score points higher than the mean for boys, but only 0.3 standard points in favour of girls for non-verbal reasoning (NVR), and 0.7 points in favour of boys for quantitative reasoning (QR). However, for all three tests there were substantial sex differences in the standard deviation of scores, with greater variance among boys. Boys were over represented relative to girls at both the top and the bottom extremes for all tests, with the exception of the top 10% in verbal reasoning. Conclusions. Given the small differences in means, explanations for sex differences in wider domains such examination attainment at age 16 need to look beyond conceptions of `ability'. Boys tend to be both the lowest and the highest performers in terms of their reasoning abilities, which warns against the danger of stereotyping boys as low achievers

Auditory inspection time and intelligence

This thesis studied the association between auditory inspection time (AIT) and psychometric measures of verbal and non-verbal cognitive abilities. I review attempts to search for basic information processing components that predict intelligence (Chapter 1), attempts to relate auditory processing speed to intelligence (Chapter 2), and attempts to relate acuity of sensory discrimination to intelligence (Chapter 3). These reviews establish certain essential requirements for a plan of research on auditory inspection time. Chapter 4 described the development of a modified AIT test. In a study of 120 undergraduates, the modified AIT test showed improved subject performance characteristics over previous AIT tasks, and AIT thresholds had low to moderate correlations with visual IT thresholds and with verbal and non-verbal cognitive ability scores. Chapter 5 described two studies. Study 1 included 84 undergraduates and showed that the AIT test had a very high split-half reliability and that about two-thirds of subjects who could perform the AIT task had response performance curves which fitted a cumulative normal ogive. The association between AIT and verbal ability appeared stronger than the AIT-non-verbal ability association in 34 of the subjects; this was also found in Study 2 which tested 119 11-year-olds. Unspeeded pitch discrimination showed a small but significant association with verbal ability in children but not in undergraduates. Results from neither study supported the suggestion that pitch discrimination was the basis for the AIT-cognitive ability association. Chapters 6 and 7 examined the associations among AIT, unspeeded pitch discrimination and an auditory backward masking recognition task which was dubbed the 'Raz' task. It was found that all three tasks were reliable, prone to practice effects and showed high intercorrelations. The AIT and Raz tasks appeared to share common variance not related to pitch discrimination. In a confirmatory factor analysis of over 100 13-year-olds latent variables from the three auditory tests representing auditory processing speed and pitch discrimination both had significant associations with a factor common to verbal and non-verbal intelligence, though speed was the more important factor. Chapter 8 reported the results of a longitudinal study of AIT and cognitive ability in over 100 children from age 11 to age 13. Using structural modelling techniques to create competing causal models and then testing these for goodness-of-fit to the data, some support was found for the suggestion that auditory processing abilities at age 11 might have a causal influence on later verbal and non-verbal abilities rather than the converse. Chapter 9 provided a thematic resume of the studies conducted in the thesis. It was concluded that the corrected AIT-cognitive ability association was in the region of -0.5, and that some progress had been made in explaining this association. In addition, a strong plea was made for AIT and visual IT to be integrated with other models of auditory and visual information processing which exist. Suggestions were made for future research on auditory and visual processing and intelligence

Occupational complexity and lifetime cognitive abilities

OBJECTIVE: To examine associations between complexity of main lifetime occupation and cognitive performance in later life. METHODS: Occupational complexity ratings for data, people, and things were collected from the Dictionary of Occupational Titles for 1,066 individuals (men = 534, women = 532) in the Lothian Birth Cohort 1936. IQ data were available from mean age 11 years. Cognitive ability data across the domains of general ability, processing speed, and memory were available at mean age 70 years. RESULTS: General linear model analyses indicated that complexity of work with people and data were associated with better cognitive performance at age 70, after including age 11 IQ, years of education, and social deprivation. CONCLUSIONS: The current findings are supportive of the differential preservation hypotheses that more stimulating environments preserve cognitive ability in later life, although the continued effects into old age are still debated. Studies that have early-life cognitive ability measures are rare, and the current study offers interesting prospects for future research that may further the understanding of successful aging

Two cheers for the cognitive irregulars:Intelligence’s contributions to ageing well and staying alive

Here, intelligence is taken to mean scores from psychometric tests of cognitive functions. This essay describes how cognitive tests offer assessments of brain functioning—an otherwise difficult-to-assess organ—that have proved enduringly useful in the field of health and medicine. The two “consequential world problems” (the phrase used by the inviters of this essay) addressed in this article are (i) the ageing of modern societies (and the resulting increase in the numbers of people with ageing-related cognitive decrements and dementias) and (ii) health inequalities, including mortality. Cognitive tests have an ubiquitous place in both of these topics, i.e., the important fields of cognitive ageing and cognitive epidemiology, respectively. The cognitive tests that have sprouted in these fields are often brief and not mainstream, large psychometric test batteries; I refer to them as ‘irregulars’. These two problems are not separate, because results found with mental/cognitive/intelligence tests have produced a growing understanding that intelligence and health have a reciprocal, life-long relationship. Intelligence tests contribute to the applied research that is trying to help people to stay sharp, stay healthy, and stay alive

Lower Ankle-Brachial Index Is Related to Worse Cognitive Performance in Old Age

Objective: We aimed to study the associations between peripheral artery disease (PAD) and ankle-brachial index (ABI) and performance in a range of cognitive domains in nondemented elderly persons. Methods: Data were collected within the Lothian Birth Cohort 1921 and 1936 studies. These are two narrow-age cohorts at age 87 (n = 170) and 73 (n = 748) years. ABI was analyzed as a dichotomous (PAD vs. no PAD) and a continuous measure. PAD was defined as having an ABI less than 0.90. Measures of nonverbal reasoning, verbal declarative memory, verbal fluency, working memory, and processing speed were administered. Both samples were screened for dementia. Results: We observed no significant differences in cognitive performance between persons with or without PAD. However, higher ABI was associated with better general cognition (β = .23, p = .02, R(2) change = .05) and processing speed (β = .29, p < .01, R(2) change = .08) in the older cohort and better processing speed (β = .12, p < .01, R(2) change = .01) in the younger cohort. This was after controlling for age, sex, and childhood mental ability and excluding persons with abnormally high ABI (>1.40) and a history of cardiovascular or cerebrovascular disease. Conclusion: Lower ABI is associated with worse cognitive performance in old age, especially in the oldest old (>85 years), possibly because of long-term exposure to atherosclerotic disease. Interventions targeting PAD in persons free of manifest cardiovascular and cerebrovascular disease may reduce the incidence of cognitive impairment and dementia

Does cognitive ability influence responses to the Warwick-Edinburgh Mental Well-Being Scale?

It has been suggested that how individuals respond to self-report items relies on cognitive processing. We hypothesized that an individual's level of cognitive ability may influence these processes such that, if there is a hierarchy of items within a particular questionnaire, as demonstrated by Mokken scaling, the strength of that hierarchy will vary according to cognitive ability. Using data on 8,643 men and women from the National Child Development Survey (1958 birth cohort; Power, &amp; Elliott, 2006), we investigated, using Mokken scaling, whether the 14 items that make up the Warwick-Edinburgh Mental Well-Being Scale (Tennant et al., 2007)-completed when the participants were 50 years of age-form a hierarchy and whether that hierarchy varied according to cognitive ability at age 11 years. Among the sample as a whole, we found a moderately strong unidimensional hierarchy of items (Loevinger's coefficient [H] = 0.48). We split participants into 3 groups according to cognitive ability and analyzed the Mokken scaling properties of each group. Only the medium and high cognitive ability groups had acceptable (?0.3) invariant item ordering (assessed using the HT statistic). This pattern was also found when the 3 cognitive ability groups were assessed within men and women separately. Greater attention should be paid to the content validity of questionnaires to ensure they are applicable across the spectrum of mental ability

Reaction times match IQ for major causes of mortality:Evidence from a population based prospective cohort study

Introduction: The association of premorbid cognitive ability with all-cause mortality is now well established. However, since all-cause mortality is relatively uninformative about aetiology, evidence has been sought, and is beginning to accumulate, for associations with specific causes of mortality. Likewise, the underlying causal pathways may be illuminated by considering associations with different measures of cognitive ability. For example, critics of IQ type measures point to possible cultural or social biases and there is, consequently, a need for more culturally neutral measures such as reaction times. We examine the associations of cognitive ability with major causes of mortality, including: cardiovascular disease, cancer and respiratory disease and compare the results for a standard IQ test, the Alice Heim 4 (AH4), with those for simple and four-choice reaction times. Methods: Data were derived from the oldest cohort of the West of Scotland Twenty-07 Study. Participants were randomly sampled from the Central Clydeside Conurbation, a mainly urban area centred on Glasgow city. At baseline, aged 56, they were interviewed in their homes by trained interviewers; the AH4 was administered and reaction times measured using a portable electronic device. Vital status was ascertained via linkage to the NHS central register. Cox regression was used in SAS 9.4 for the main analyses. Adjustments were made for sex, smoking status and social class. Results: Full data on AH4, RT and covariates were available for 1350 out of 1551. During 29 years of follow-up, there were 833 deaths: 279 cardiovascular disease (CVD) (168 CHD; 68 stroke); 291 cancer; 97 respiratory disease; 42 digestive disease; and 39 dementia. The 85 remaining deaths were a heterogeneous mixture with no cause accounting for more than 14. AH4 scores were associated with most major causes. Digestive disease and dementia had similar effect sizes but were not significant. Within cardiovascular disease, there was an association with coronary heart disease but not stroke. The association with cancer was primarily due to those cancers related to smoking. RT measures were mostly associated with the same causes of death. Where significant, effects were in the same directions and of similar magnitude. That is, lower AH4 scores, longer reaction times, and more variable reaction times were all associated with increased mortality risk from the major causes of death. A summary measure of RT outperformed the AH4 for most causes. Conclusion: The association between intelligence with mortality from the major causes is also seen with reaction times. That effect sizes are of similar magnitude is suggestive of a common cause. It also implies that the association of cognitive ability with mortality is unlikely to be due to any social, cultural or educational biases that are sometimes ascribed to intelligence measures