Measuring Fluid Intelligence Research Articles

Measuring fluid intelligence on a ratio scale: Evidence from nonverbal classification problems and information entropy

Drawing on the g factor and information theory literatures, the relationship between the four subtests of the Culture-Fair Intelligence Test (CFIT) and the entropy of the Ruiz Absolute Scale of Complexity Management (R-ASCM) was investigated. In results based on data collected from 186 university students, the entropy of the R-ASCM mostly loads the first principal component extracted from the CFIT subtests and shows a corresponding strong relationship with the item difficulty of the R-ASCM. Because entropy is a ratio scale of complexity--with a true zero and units called bits--these findings suggest that entropy is the right vehicle for measuring the information contained in nonverbal intelligence tests.

Investigation of a functional quinine oxidoreductase (NQO2) polymorphism and cognitive decline

NAD(P)H dehydrogenase quinone 2 (NQO2) is a quinone reductase whose functions include the reduction of both oxidative stress during the redox cycle and neurotoxicity caused by the metabolism of catecholamines. We have investigated a functional non-synonymous exon 3 single nucleotide polymorphism (rs1143684) within the NQO2 gene for association with cognitive decline using a cohort of 722 community-dwelling older individuals aged 50 years and over. The volunteers had completed tests that measured fluid intelligence, processing speed, immediate/delayed verbal recall and semantic memory. We observed a nominal significant association between this polymorphism and the trajectory of delayed memory recall over time ( p = 0.029). No other associations were seen with the decline of other cognitive abilities.

Some factors underlying mathematical performance: The role of visuospatial working memory and non-verbal intelligence

Passive and active visuospatial working memory (VSWM) were investigated in relation to maths performance. The mental rotation task was employed as a measure of active VSWM whereas passive VSWM was investigated using a modified Corsi Blocks task and a matrix pattern task. The Raven Progressive Matrices Test measured fluid intelligence. A total of 128 students, aged 15–16, served as participants. Fluid intelligence and passive VSWM accounted for variance in overall maths performance. Active VSWM exhibited significant correlations with maths measures, but in a series of regression analyses most of its effect was observed to be mediated by fluid intelligence. Different subscores of mathematical skills (geometry, word problems, and mental arithmetic) were accounted for by fluid intelligence and different measures of VSWM. The educational implications of the results are discussed.

Nonepisodic Memory Deficits in Amnestic MCI

To (a) compare patients with amnestic Mild Cognitive Impairment (MCI), mild Alzheimer disease (AD), and a group of healthy elderly persons on nonepisodic memory measures; (b) examine which measures are independent of level of education in the groups studied. Episodic memory impairment is a cardinal feature of preclinical AD. However, a number of other cognitive measures are also sensitive to the preclinical stage of AD and deficits in multiple domains characterize AD several years before clinical diagnosis. Patients with amnestic MCI (N=31), patients with mild probable AD (N=15), and healthy elderly controls (N=27) were compared on nonepisodic memory tasks measuring fluid intelligence, working memory, processing speed, verbal fluency, and visual-perceptual and motor functions. Amnestic MCI patients were selected based on clinical criteria and a subgroup was also selected based on psychometric criteria. Multivariate analyses of covariance, controlling for the effects of age, education, and sex, showed that fluid intelligence, working memory, processing speed, semantic fluency, visual-perceptual function, and complex motor function were significantly worse in the MCI than the elderly control group. Working memory, processing speed, semantic fluency, and complex motor tasks were significantly worse in the mild probable AD than the MCI group. The analyses were corroborated using the psychometrically derived MCI group. (a) Performance on multiple nonepisodic memory measures is affected in the preclinical stage of AD, indicating that broad cognitive impairment characterizes that stage. (b) Complex motor tasks were independent of level of education in our sample, and may have practical utility in the early detection of dementia.

The validity of the Comprehensive Test of Nonverbal Intelligence as a measure of fluid intelligence.

The current investigation examined the validity of the Comprehensive Test of Nonverbal Intelligence (CTONI), an intelligence test that is purported to measure fluid intelligence. The CTONI was evaluated in comparison with the Kaufman Adolescent and Adult Intelligence Test (KAIT), an established measure of fluid and crystallized intelligence. Ninety-seven adults were administered these instruments in counterbalanced order. Results indicated that the sample's mean CTONI Nonverbal IQ (NIQ) deviated significantly from the mean KAIT Crystallized, Fluid, and Composite IQs. The CTONI mean NIQ underestimated KAIT Fluid and Composite IQs when individual participants were subdivided into existing KAIT ability categories and mean score comparisons were made. Results also indicated that the CTONI NIQ correlated strongly and positively with the KAIT Composite and Fluid IQs. Furthermore, the CTONI Geometric NIQ scale clearly demonstrated discriminant and convergent validity, whereas, the CTONI Pictorial NIQ (PNIQ) did not.

Complexity of geometric inductive reasoning tasks: Contribution to the understanding of fluid intelligence

Studies of the complexity of geometric inductive matrix items used to measure fluid intelligence (Gf) indicate that such complexity may be related to (a) an increase in the number of figures, (b) an increase in the number of rules relating these figures, (c) the complexity of these rules, and (d) the perceptual complexity of the stimulus. One limitation of these studies is that complex items present all of these characteristics simultaneously. Thus, no information regarding their relative importance is available, nor is it clear whether all these factors have a significant effect on complexity. In the present study, two matrix tests were created by orthogonally manipulating these four sources of complexity, and the results show that perceptual organization has the strongest effect, followed by the increase in the amount of information (figures and rules). These results suggest that Gf is most strongly associated with that part of the central executive component of working memory that is related to the controlled attention processing and selective encoding.

Signs of impaired cognitive function in adolescents with marginal cobalamin status

Lack of cobalamin may lead to neurologic disorders, which have been reported in strict vegetarians. The objective of this study was to investigate whether cognitive functioning is affected in adolescents (aged 10-16 y) with marginal cobalamin status as a result of being fed a macrobiotic diet up to an average age of 6 y. Data on dietary intake, psychological test performance, and biochemical variables of cobalamin status were collected from 48 adolescents who consumed macrobiotic (vegan type) diets up to the age of 6 y, subsequently followed by lactovegetarian or omnivorous diets, and from 24 subjects (aged 10-18 y) who were fed omnivorous diets from birth onward. Thirty-one subjects from the previously macrobiotic group were cobalamin deficient according to their plasma methylmalonic acid concentrations. Seventeen previously macrobiotic subjects and all control subjects had normal cobalamin status. The control subjects performed better on most psychological tests than did macrobiotic subjects with low or normal cobalamin status. A significant relation between test score and cobalamin deficiency (P: = 0.01) was observed for a test measuring fluid intelligence (correlation coefficient: -0.28; 95% CI: -0.48, -0.08). This effect became more pronounced (P: = 0.003) within the subgroup of macrobiotic subjects (correlation coefficient: -0.38; 95% CI: -0.62, - 0.14). Our data suggest that cobalamin deficiency, in the absence of hematologic signs, may lead to impaired cognitive performance in adolescents.

Teaching inductive reasoning: some theory and three experimental studies

Based upon a prescriptive theory of inductive reasoning it is hypothesized that a training of an inductive strategy should (a) enhance performance with tests measuring fluid intelligence, (b) support learning of school-relevant declarative knowledge, and (c) improve solving of complex and dynamic problems. Three experiments are reported yielding the predicted results concerning intelligence test performance, learning and problem solving. Some implications and consequences are discussed.

Fluid intelligence after frontal lobe lesions

Generally positive correlations between different ability tests provide the evidence for a factor of “general intelligence” or Spearman's g. Though a possible neural substrate for g is suggested by executive impairments following frontal lobe lesions, preserved IQs in some frontal patients have been taken as strong evidence against this interpretation. We show that such results depend on how g is measured. Patients with superior IQs on the most clinically popular test—the Wechsler Adult Intelligence Scale—show impairments of 20–60 points on conventionally measured fluid intelligence or novel problem solving. On psychometric grounds, it is fluid intelligence that is most closely related to Spearman's g. The data suggest that g may in large part be a reflection of frontal functions.