Individual and group differences in intelligence and speed of information processing

A battery of eight different reaction time (RT) tests, measuring the speed with which individuals perform various elementary cognitive processes, and a group test of scholastic aptitude (the Armed Services Vocational Aptitude Battery, ASVAB) were given to 50 black and 56 white male vocational college students. The regression of the general factor scores of the ASVAB on the RT measures yielded a shrunken multiple correlation of 0.465. Although discriminant analyses, when applied separately to the ASVAB subtests and to the RT variables, showed highly comparable overall discrimination (over 70% correct classification) between the black and white groups, factor scores derived from the general factor (labeled ‘speed of information processing’) of the RT battery show only about one-third as large a mean black-white difference as the mean group difference on the general factor scores derived from the ASVAB. Comparisons were also made between the 106 vocational college students and 100 university students of higher average academic aptitude who had previously been tested on the same RT battery (Vernon, 1983a). These groups showed marked differences on the RT variables, the largest differences occuring on the tests that required more complex cognitive processing. The more complex RT tests also correlate most highly with the psychometric measures of ability within each group. The results are consistent with the hypothesis that individual differences and the mean differences between groups in psychometric abilities and scholastic achievement are related to differences in the speed of information processing as measured in elementary cognitive tasks.     

The construct of general intelligence

The construct of general intelligence is discussed in a number of different contexts. The fundamental empirical basis for it is the positive trend among the smallest correlations among cognitive measures. Differences among factor models which recognize this in different ways are discussed. Evidence for the general factor in intelligence is also found in the difficulty in finding evidence for differential validity of tests from one criterion to another. Performance on Piagetian tasks reflects mainly general intelligence. Individual differences in aural comprehension of language anticipate later individual differences in intellectual development. Selective forces which produce differences among schools operate largely on the general factor. To the extent that there is a genetic contribution to individual differences on cognitive tests, it appears to be to the general factor variance. Social class differences among whites appear to be largely on the general factor, but black-white differences require other dimensions. Although the general factor is, in a sense, real, it is not interpreted as an entity within the organism. Instead it is an abstraction resulting from the many genes, the many environmental pressures, and the many neural structures involved in the wide variety of human behaviors which can be labelled cognitive or intellectual.     

Individual Differences in Decision Making Depend on Cognitive Abilities,Monitoring and Control

Decision making is the process by which actions are constructed and initiated. Across many research streams, this can be explained in terms of three broad cognitive processes: cognitive abilities that construct judgements and potential courses of action, and interacting monitoring and control processes that determine when to initiate them as behaviour. The aim of this research was to investigate the generality of individual differences in these processes, and their power to predict patterns of decision behaviour identified in our previous research. Undergraduate participants (N = 364) completed nine tests assessing cognitive abilities, monitoring confidence, control thresholds and various patterns of decision behaviour. The tests differed in their cognitive ability requirements and the nature of the payoffs associated with decisions. Cognitive abilities were a strong predictor of individuals' decision competence and optimality, while monitoring confidence and control thresholds were strong and unique predictors of their overall decisiveness, and reckless and hesitant errors. These results were strongest when the measures of cognitive abilities and monitoring confidence were derived from tests with the same cognitive requirements as the tests used to derive the decision behaviours and when the control threshold measure was derived from tests with the same decision payoffs as the test used to derive the decision behaviours. This effect was particularly pronounced for control thresholds, highlighting the domain‐specific nature of cognitive control processes. These findings demonstrate how cognitive abilities, monitoring output and control thresholds interact with cognitive requirements and context‐specific payoffs to drive individual differences in decision‐making behaviour. Copyright © 2016 John Wiley & Sons, Ltd.     

The role of mathematical skill in sex differences on Raven’s Matrices

This study replicated a previously reported male advantage on certain items of Raven’s Matrices and found no sex differences in performance on other items. We refer to the latter as analytic (1) items and the former as analytic (2) items. Reasons for the male advantage were investigated by correlating scores obtained by male and female high school students on analytic (1) and analytic (2) items with their scores on tests of spatial, verbal and mathematical ability. There were no sex differences in the magnitude of the correlations between scores on analytic (2) items and the two spatial and verbal tests. In contrast, males but not females showed a significantly higher correlation of maths with analytic (2) than with analytic (1). The results suggest the Raven’s Matrices may engage different, more specific cognitive processes in males and more general cognitive processes in females.     

Black-white bias in ‘cultural’ and ‘noncultural’ test items

The original data of McGurk's classic study of black-white differences on cultural and noncultural tests is re-analyzed at the item level to investigate the role of possible item biases that would cause the noncultural items to be relatively more difficult than the cultural items for blacks than for whites. The evidence indicates that McGurk's results cannot be explained in terms of item biases, but appear to be the result of the noncultural items requiring more sheer reasoning ability than the cultural items, which depend more on acquired information.     

Humphreys's attenuated test of Spearman's hypothesis

Humphreys's test of Spearman's hypothesis (viz., that the size of the standardized black-white differences on various psychometric tests is positively related to the tests' loadings on g, the general intelligence factor) is methodologically weak. It is based on comparison of a fairly representative sample of the black population of U.S. school children with a highly selected sample of the white school population, representing the lowest 15 to 20% of whites in socio-economic status (SES). A fair test of the hypothesis requires that the black and white samples should not be selected on any g-correlated variable, such as SES. Selection attenuates and distorts the relationship between tests' g loadings and the magnitude of the standardized mean black-white differences on the tests. Other unorthodox conditions in Humphreys's study, such as performing factor analysis on the test-score means of various arbitrary demographic groups instead of on individual test scores inflates tests' g loadings and biases the test of Spearman's hypothesis by restriction of reliable variance in g loadings. Humphreys's study cannot be considered a proper replication of Jensen's examination of Spearman's hypothesis in 11 different studies comprising 74 different tests, which consistently bears out Spearman's hypothesis.     

Inhibitory processes, working memory, phonological awareness, naming speed, and early arithmetic achievement

This study identified the cognitive processes that underlie the individual differences in early mathematical performance in elementary school children. Taking into account the Baddeley framework multicomponent model, the inhibitory processes, working memory, phonological awareness, and naming speed are considered to be related to early math learning. To examine this relationship, we compared the performance of a total of 424 typically developing middle-class children, aged between 4 and 7 years in a battery of cognitive and early numeric tests: The Utrecht Early Numeracy Test, the Rapid Automatized Naming Test, Spanish version of the Stroop task, the Numeracy Interference Test, Digit Span test, and Phonological Knowledge Test. The mean age of the participants was 72.21 months (sd = 14.8), and 48.6% were male and 51.4% were female. The results demonstrated that children performing worst on central executive, phonological processing, and inhibitory processes showed lower results in early mathematical tasks measured by The Utrecht Early Numeracy Test. Results supported the notion that the executive system is an important predictor of children's mathematical performance.     

Emergent Leadership Behaviors: The Function of Personality and Cognitive Ability in Determining Teamwork Performance and KSAs

This study investigated the theoretical underpinnings of individual differences in emergent leadership behaviors and their relationships to teamwork processes and outcomes. Both personality and cognitive ability were utilized to examine behaviors of leadership emergence, team performance, and KSAs. Three hundred and twenty undergraduate psychology students completed personality and cognitive ability tests and then formed sixty-seven mixed-gender teams. Members rated each other on emergent leadership behaviors as well as their team on specific interpersonal and self-management KSAs. Results revealed that extroversion, openness to experience and cognitive ability were predictive of emergent leadership behaviors. Conscientiousness and cognitive ability were associated with team performance. Implications and future directions for research are discussed.     

Sex differences in theory of mind: A male advantage on Happé's “cartoon” task

It is a commonly held stereotype that women show superior performance on tests of social cognition such as face processing and theory of mind (ToM) compared to men. However, such purported differences have not been empirically tested. In this study 40 healthy men and 40 women matched for age and years of education completed a well-known experimental ToM test requiring the attribution of either physical or mental states (Happé's cartoon task). Men showed superior performance compared to women, with a medium effect size, on both the mental state and physical state cartoons. It is suggested that men may use a cognitive systemising strategy during these tasks. The results emphasise the task-specific nature of sex differences in social cognition and necessitate future work to elucidate individual differences at the interface of cognitive and affective processes.     

A preliminary investigation of sex differences in associations between emotion regulation difficulties and higher-order cognitive abilities

The present study sought to clarify the cognitive correlates of emotion regulation difficulties (ERD). Further, because prior evidence suggests sex differences in emotion regulation, sex was examined as a moderator of associations between cognitive abilities and ERD. Participants (N = 154) completed self-report measures of ERD, and were administered neuropsychological tests assessing crystallized and fluid intelligence, as well as various components of executive functioning. Bivariate correlations and results from regression analyses suggested sex-dependent associations among cognitive processes and ERD. For men, inhibition of dominant response tendencies was associated with lower ERD, whereas for women, a host of executive abilities (e.g., greater inhibition, cognitive flexibility, semantic processing, abstract reasoning) were associated with greater ERD. Implications for the neurocognitive conceptualization of emotion dysregulation will be discussed.     

Individual Differences in Social Dominance Orientation Predict Support for the Use of Cognitive Ability Tests

This study investigates the personality processes involved in the debate surrounding the use of cognitive ability tests in college admissions. In Study 1, 108 undergraduates (M_age = 18.88 years, 60 women, 80 Whites) completed measures of social dominance orientation (SDO), testing self‐efficacy, and attitudes regarding the use of cognitive ability tests in college admissions; SAT/ACT scores were collected from the registrar. Sixty‐seven undergraduates (M_age = 19.06 years, 39 women, 49 Whites) completed the same measures in Study 2, along with measures of endorsement of commonly presented arguments about test use. In Study 3, 321 American adults (M_age = 35.58 years, 180 women, 251 Whites) completed the same measures used in Study 2; half were provided with facts about race and validity issues surrounding cognitive ability tests. Individual differences in SDO significantly predicted support for the use of cognitive ability tests in all samples, after controlling for SAT/ACT scores and test self‐efficacy and also among participants who read facts about cognitive ability tests. Moreover, arguments for and against test use mediated this effect. The present study sheds new light on an old debate by demonstrating that individual differences in beliefs about hierarchy play a key role in attitudes toward cognitive ability test use.     

Separating sensitivity from response bias: implications of comparisons of yes-no and forced-choice tests for models and measures of recognition memory

A fundamental challenge to psychological research is the measurement of cognitive processes uncontaminated by response strategies resulting from different testing procedures. Test-free estimates of ability are vital when comparing the performance of different groups or different conditions. The current study applied several sets of measurement models to both forced-choice and yes-no recognition memory tests and concluded that the traditional signal-detection model resulted in distorted estimates of accuracy. Two-factor models were necessary to separate memory sensitivity from response bias. These models indicated that (a) memory accuracy did not differ across the tests and (b) the tests relied on the same underlying memory processes. The results illustrate the pitfalls of using a single-component model to measure accuracy in tasks that reflect 2 or more underlying processes.     

The heritability of cognitive functioning in very old adults: evidence from Danish twins aged 75 years and older

Heritable influences on cognitive functioning were investigated in a sample of 403 pairs of like-sex Danish twins aged 75 years and older. Twins completed the Mini-Mental State Examination and 3 other cognitive tests. Genetic factors accounted for 26-54% of the variance on these measures, with the balance being due to environmental factors that create differences rather than similarities among reared-together relatives. Deleting twins with severe cognitive impairment had little effect on the results, indicating that the heritability of cognitive functioning was not due entirely to genes affecting dementia. Neither age nor gender moderated twin similarity, and differential social contact could not account for correlation differences between monozygotic and dizygotic twins. These results replicate G. E. McClearn et al.'s (1997) study in indicating substantial genetic influences on late-life cognitive functioning.     

The cognitive functioning of older adult instrumental musicians and non-musicians

This study examined similarities and differences in the cognitive profiles of older adult instrumental musicians and non-musicians. We compared neuropsychological test scores among older adult non-musicians, low-activity musicians (<10 years of lessons), and high-activity musicians (≥10 years of lessons), controlling for self-reported physical and social activity, years of education, and overall health. Significant differences among groups were found on tasks of visual spatial ability, naming, and executive functioning. No significant differences were found on tests of attention/processing speed, or episodic memory. The current study supports late life cognitive benefits of early musical training, but only in select cognitive domains, including language, executive functioning, and visual spatial ability. The results are discussed in the context of cognitive reserve and aging.     

Bayesian techniques for analyzing group differences in the Iowa Gambling Task: A case study of intuitive and deliberate decision-makers

The Iowa Gambling Task (IGT) is one of the most popular experimental paradigms for comparing complex decision-making across groups. Most commonly, IGT behavior is analyzed using frequentist tests to compare performance across groups, and to compare inferred parameters of cognitive models developed for the IGT. Here, we present a Bayesian alternative based on Bayesian repeated-measures ANOVA for comparing performance, and a suite of three complementary model-based methods for assessing the cognitive processes underlying IGT performance. The three model-based methods involve Bayesian hierarchical parameter estimation, Bayes factor model comparison, and Bayesian latent-mixture modeling. We illustrate these Bayesian methods by applying them to test the extent to which differences in intuitive versus deliberate decision style are associated with differences in IGT performance. The results show that intuitive and deliberate decision-makers behave similarly on the IGT, and the modeling analyses consistently suggest that both groups of decision-makers rely on similar cognitive processes. Our results challenge the notion that individual differences in intuitive and deliberate decision styles have a broad impact on decision-making. They also highlight the advantages of Bayesian methods, especially their ability to quantify evidence in favor of the null hypothesis, and that they allow model-based analyses to incorporate hierarchical and latent-mixture structures.     

Analyzing Goal-Striving Processes and a Test of the Generalizability of Perceptual Control Theory

Theories that articulate dynamic processes are relatively rare, but methods for testing the theories are even rarer. This study illustrates two methods for examining goal-striving processes and a tool for collecting dynamic data. The first method tests a hypothesis regarding what variable the participants are attempting to maintain. The second method involves creating multilevel models used to describe the dynamic data generated by study participants, which can be used to test between- and within-subject manipulations or differences. The tool is a research simulation of a manager's role in scheduling subordinates in a hospital wing. Together these methods and the tool are used to test the generalizability of perceptual control theory in explaining striving for cognitive goals. The results confirm the viability of a control theory accounting of goal striving and highlight the potential of the methods and the research tool in future research.     

Effects of home nest odors on black-white preference in the developing rat: implications for developmental learning research

Developing animals 17 and 30 days of age were tested for black-white preference in the presence of either clean shavings or soiled bedding material from the home cage. Home nest shavings markedly reduced dark preference in 17-day-old rats but had no effect on dark preference in 30-day-old rats. Because many developmental studies have used two-compartment, black and white chambers to study the effects of familiar home nest shavings on learning and memory, it may be that differential preference for black influenced the results obtained. The apparent alleviation of learning and memory deficits produced by the presence of home nest shavings may have been the result of changes in black-white preference rather than differences in learning and memory per se. Similar influences may underlie the effects of home nest stimuli on other learning tasks such as spatial alternation.     

Residual effects of cigarette smoking on cognitive performance in normal aging

The present study examined the residual effects of smoking status on cognitive function in 76 nondemented older adults. Current smokers, ex-smokers, and nonsmokers who were screened for health and intellectual impairments were administered a battery of standardized neuropsychological tests to measure problem solving, psychomotor speed, memory, attention span, perception, and language production. Performance decrements were found for smokers on measures of psychomotor speed. No between-group differences were noted on any of the nonspeeded tests. There were no differences between nonsmokers and ex-smokers on any measures. The results suggest that the residual effects of current cigarette smoking negatively influence speeded cognitive capabilities in older adults.     

Field dependence-independence (FDI) cognitive style: an analysis of attentional functioning

Previous research has indicated that field-dependent children display poorer performance than field-independent children in almost all academic subjects and cognitive tasks. However, the processes underlying this poorer performance remain unclear. The present study aimed to assess whether children with different FDI cognitive styles show differences in performance of tasks measuring aspects of attentional functioning. Specifically, 149 children aged 8 - 11 years were classified according to FDI cognitive style (field-dependent, intermediate, or field-independent), and to storage capacity (Digits Forward Test), verbal working memory (Digits Backward Test), capacity to focus, shift, and maintain attention (Digit Symbol Test), and capacity for sustained attention (Visual Search and Attention Test). Field-independent children displayed better performance than intermediate and field-dependent children on all tests except the Digits Forward Test. Theoretical and practical implications of these results are discussed.     

Adolescent pregnancy and infant mortality: isolating the effects of race

Researchers continue to accept the untested assumption that the difference between black and white infant mortality rates is largely attributable to race-linked differences in teenage pregnancies (Wise, 1984). The basic notion is that the inordinately high black teenage pregnancy rate (because of its association with low birth weight births) accounts for this difference. This paper tests this key assumption directly and finds only partial support for it. It then argues that the key to the black-white difference in infant mortality is poverty, not teenage pregnancy. Using data from the state of North Carolina, the results suggest that poverty, not race, plays the crucial role in infant mortality.