On intelligence II: A neo-Spearman model to replace Cattell's theory of fluid and crystallized intelligence

While many empirical studies now support second-order simple structure factor analytic distinctions consistent with Cattell's theory of fluid and crystallized intelligence, the hierarchical order analyses carried out in the present study show that these factors are structured so as to suggest a neo-Spearman hierarchical model where fluid intelligence is equivalent to a general intelligence factor and broad group factors of verbal-educational knowledge, speediness, and visualization appear. The two models have different implications regarding the status of the fluid and crystallized "intelligence" factors and the relationship between them.     

Openness, fluid intelligence, and crystallized intelligence: Toward an integrative model

Many studies are concerned with the bivariate relationships between Openness, fluid intelligence (Gf), and crystallized intelligence (Gc). Results suggest an influence of Gf and Openness on Gc. However, the overlap between Gf and Openness is rarely controlled for. Moreover, interaction effects or longitudinal influences are also often neglected. The present two studies aimed to elucidate exactly these interactions and longitudinal influences. Besides a main effect of Gf on Gc, Study 1 (N = 180) revealed an interaction effect between Openness and Gf. Study 2 utilized longitudinal data (N = 172) and identified an effect of Openness on the development of Gf. Gf and Openness predicted Gc 6 years later. A model integrating the results and providing a theoretical framework and outlook is proposed.     

Gains in fluid intelligence after training non-verbal reasoning in 4-year-old children: a controlled, randomized study

Fluid intelligence (Gf) predicts performance on a wide range of cognitive activities, and children with impaired Gf often experience academic difficulties. Previous attempts to improve Gf have been hampered by poor control conditions and single outcome measures. It is thus still an open question whether Gf can be improved by training. This study included 4-year-old children (N = 101) who performed computerized training (15 min/day for 25 days) of either non-verbal reasoning, working memory, a combination of both, or a placebo version of the combined training. Compared to the placebo group, the non-verbal reasoning training group improved significantly on Gf when analysed as a latent variable of several reasoning tasks. Smaller gains on problem solving tests were seen in the combination training group. The group training working memory improved on measures of working memory, but not on problem solving tests. This study shows that it is possible to improve Gf with training, which could have implications for early interventions in children.     

Gray matter correlates of fluid,crystallized, and spatial intelligence: Testing the P-FIT model

The parieto-frontal integration theory (P-FIT) nominates several areas distributed throughout the brain as relevant for intelligence. This theory was derived from previously published studies using a variety of both imaging methods and tests of cognitive ability. Here we test this theory in a new sample of young healthy adults (N = 100) using a psychometric battery tapping fluid, crystallized, and spatial intelligence factors. High resolution structural MRI scans (3T) were obtained and analyzed with Voxel-based Morphometry (VBM). The main findings are consistent with the P-FIT, supporting the view that general intelligence (g) involves multiple cortical areas throughout the brain. Key regions include the dorsolateral prefrontal cortex, Broca's and Wernicke's areas, the somato-sensory association cortex, and the visual association cortex. Further, estimates of crystallized and spatial intelligence with g statistically removed, still share several brain areas with general intelligence, but also show some degree of uniqueness.     

Working memory and fluid intelligence in young children

The present study investigates how working memory and fluid intelligence are related in young children and how these links develop over time. The major aim is to determine which aspect of the working memory system—short-term storage or cognitive control—drives the relationship with fluid intelligence. A sample of 119 children was followed from kindergarten to second grade and completed multiple assessments of working memory, short-term memory, and fluid intelligence. The data showed that working memory, short-term memory, and fluid intelligence were highly related but separate constructs in young children. The results further showed that when the common variance between working memory and short-term memory was controlled, the residual working memory factor manifested significant links with fluid intelligence whereas the residual short-term memory factor did not. These findings suggest that in young children cognitive control mechanisms rather than the storage component of working memory span tasks are the source of their link with fluid intelligence.     

Working memory, intelligence and reading ability in children

The dimensions of working memory in children and the relationships between working memory capacity, reasoning and reading ability were investigated. Simple and complex span tests were administered to 280 grade four, five and six elementary school children. Simple span tests were hypothesized to measure the capacity to temporary store information in working memory. Complex span tests were thought to reflect the simultaneous storage and processing of information. In addition, tests for reasoning, reading comprehension and reading speed were administered. Confirmatory factor analyses showed that the various tests for working memory formed one factor, which was interpreted as temporal storage capacity. The analyses revealed also that working memory and reasoning both were related to reading comprehension, but that these constructs differed in their relations to reading speed.     

Investigating the relationship between trait and ability emotional intelligence and theory of mind

Theoretical links between emotional knowledge and theory of mind (ToM) have previously been proposed. This study investigates this relationship using measures of both ability and trait emotional intelligence (EI). Our sample comprised 194 children, divided into two age groups (5–7 years and 8–10 years). Children participated in measures of false belief understanding, advanced tests of ToM, ability EI and trait EI, and a standardized language assessment. For both age groups, we found that only ability EI was related to false belief understanding. Furthermore, regression analyses revealed that the understanding and managing branches of ability EI predicted unique variance in false belief understanding once controlling for age, language, and the other ability EI branches. Trait EI failed to display any association with false belief understanding. Ability and trait EI were associated with more advanced ToM tasks undertaken only by the older sample. These results offer support for previous research that has found a relationship between emotion perception and labelling and ToM. They also provide new knowledge: (1) higher order emotional knowledge, measured by ability EI, is associated with advanced ToM; and (2) emotional self efficacy, as measured by trait EI, is also important in advanced ToM. Furthermore, they provide the first account of associations between standardized EI measures and ToM.     

Fluid and crystallized intelligence: effects of diffuse brain damage on the WAIS

In the 1940's two forms of intelligence, fluid and crystallized, were postulated. Active mental processing (WAIS performance subtests) were fluid while well learned abilities (WAIS verbal subtests) were crystallized. Brain damage was considered to affect fluid abilities more than crystallized. WAIS scores comparing normal and diffusely organically damaged subjects indicated that, as hypothesized, the verbal subtests were more affected than the performance subtests.     

Empathy,sex and fluid intelligence as predictors of theory of mind

Individual differences in theory of mind (ToM) are affected by a variety of factors. We investigated the relationship between empathy, sex and fluid intelligence (FI) as predictors of ToM in a random probabilistic sample of secondary students. First, we explored whether sex, as well as high, average or low levels of empathy and FI affect ToM performance. Furthermore, we assessed the contribution of empathy, sex and FI in predicting ToM by using a path analysis. This method allows testing of causal models of directed dependencies among a set of variables. The causal dependencies of empathy, sex and fluid intelligence were confirmed and identified. In addition, the model confirmed the direct effect of empathy, sex and fluid intelligence on ToM; and the indirect effect of sex mediated by empathy. Thus, individual differences in ToM levels are partially attributable to sex, empathy and fluid intelligence variability, raising important considerations for clinical research as well as ToM’s theoretical models of domain specificity.     

Handedness and spatial ability in children: further support for Geschwind's hypothesis of "pathology of superiority" and for Annett's theory of intelligence.

Spatial ability of 60 left-handed and 60 right-handed school children was investigated using a battery of nine tasks. The results do not agree with Levy's (1969, 1976) theory predicting spatial inferiority of left-handed individuals. Instead, higher performance by left-handed children provided further support for Annett's (Annett & Manning, 1989) theory on intelligence and for Geschwind's (Geschwind & Galaburda, 1985) hypothesis of "pathology of superiority." The distinction of left-handed and right-handed individuals into familial and nonfamilial groups appeared to be psychologically equivocal according to our results.     

Assessment of the global intelligence and selective cognitive capacities in preterm 8-year-old children

The aim of this study was to assess various cognitive abilities such as attention, IQ, reasoning, and memory related to academic achievement in 8- and 9-year-old preterm children. A total of 141 children were assessed. The preterm group (=37 weeks) comprised 63 children and was compared to 78 full-term children. Attention was evaluated using the d2 Selective Attention test, and the IQ by the L-M form of the Stanford-Binet Intelligence Scale, establishing a profile of abilities: perception, memory, comprehension, reasoning, and verbal fluency. Significant differences in IQ were found between the preterm and full-term children. Of the cognitive abilities assessed, the only significant differences were found in verbal fluency, with preterm boys showing lower verbal fluency scores than full-term children. In conclusion, all preterm groups have attention ability similar to that of full-term children. However, preterm children obtain lower scores in intelligence measures. In addition, preterm boys have verbal fluency difficulties. Taking into account the increase in preterm births, suitable intervention programs must be planned to attend the difficulties found.     

Toward a theory of intelligence: Contributions from research with retarded children

One approach to the understanding of intelligence is through research with retarded children and adults. Any characterization of the way(s) in which they differ from nonretarded individuals results in a specification of important components of intelligence. In this paper, we deal with two general areas of research. In one, centering on the role of control processes in memory and problem-solving situations, we argue that research with the retarded has succeeded in identifying a major component of intelligence. The results from a large number of experiments lead us to the conclusion that a hallmark of intelligence is the ability to generalize information from one situation to another, and that this ability in turn depends upon effective “executive control.” In areas where less research with retarded individuals has been doen, we suggest that comparative/developmental work is necessary to gain a better understanding of the processes in question. We illustrate this point by discussing some work aimed at locating individual differences in parameters representing basic components of general information-processing systems.     

Relationships between Machiavellianism, emotional intelligence and theory of mind in children

The current study investigates the associations of Machiavellianism (Mach) with trait and ability emotional intelligence (EI), and theory of mind (ToM) in 109 primary school children. Consistent with previous research with adults, negative associations were found between Mach and social and emotional understanding. Subsequent multiple regression analyses for girls showed that being more adept at emotional and social understanding does not lead them to manipulate others in social encounters. This was not the case for boys. These findings are discussed in relation to other social and individual difference variables that impact on Mach, particularly amongst boys.     

A theory of intelligence: I. span and the complexity of stimulus control

A theory of intelligence is couched in stimulus-response terms, bridging the gap between S-R and cognitive psychology. The chief theoretical concepts are span ability (a capacity notion), response string (sequentially cued responses), and complexity of stimulus control (task complexity). Span is equated with the ability to respond appropriately when several cues are conjunctively relevant for correct performance (complex stimulus control). So defined, span is consistently and broadly related to many aspects of intelligent behavior.     

Comparison of visual-discrimination ability of brain-injured and non-brain-injured children of normal intelligence.

A set of 106 multiple-choice geometric designs were administered to 23 children diagnosed as minimally brain-damaged and 23 control children. All children were between the ages of 4 and 12 yr. and were matched for age and intelligence. Differences between the two groups suggest that, although rotation and reversal errors significantly discriminate the groups, factors which lead to distractions are more discriminative. The data suggest the possibility of an easily administered and objectively scored instrument which is relatively independent of motor development in children.     

Item-response theory modeling of IQ gains (the Flynn effect) on crystallized intelligence: Rodgers' hypothesis yes,Brand's hypothesis perhaps

Potential explanations for generational intelligence test score gains continue to be subject to intense debate and scrutiny in the scientific community. However, the explanatory value of some of the proposed causes remains difficult to determine, since only little empirical evidence is available. To clarify the role of two scarcely investigated theories accounting for the Flynn effect, this study set out to examine the role of changing test-taking behavior (Brand's hypothesis) and of a narrowing of the IQ ability distribution (Rodgers' hypothesis). Archival records of crystallized intelligence test performance over a time-span of 17 years of a large number of psychiatric inpatients and outpatients in Austria were investigated (N = 5445; 1978–94). This sample was particularly suitable to investigate our hypotheses since participants were under no pressure to perform which makes observed changes in test taking behavior attributable to personal style and ability rather than differential performance in pressure situations. Analytical approaches of both classical test theory and item response theory (IRT) yielded gains of 1.0 to 2.4 IQ points per decade. Test-taking behavior indicative of guessing and decreasing population IQ variability appeared to contribute both to IQ test score gains. IRT-based analyses showed that gains were largely preserved when controlling for highest educational qualification, while the test instrument showed measurement invariance between cohorts. However, IRT-based results also suggested that changes in test-taking behavior might not necessarily reflect increased guessing, but item drift instead. In all, this evidence emphasizes better performance of individuals of the lower tail of the IQ ability distribution in more recent years as one important contributing factor for generational IQ test score gains.     

Memory and intelligence: Age and ability differences in strategies and organization of recall

Proficiency at organizing information for recall is one aspect of memory functioning which could be expected to be related to intelligence, or general ability. Comparisons of children of average and of superior ability (Kuhlmann-Anderson scores) in a multitrial free-recall learning task confirmed this prediction: Both level of recall and amount of sequential organization were significantly higher for the superior ability groups. Mental age definitions of intelligence imply that equivalent performance by children of different chronological ages will be based on qualitatively similar cognitive processes. This assumption was not confirmed. Age-related changes in mnemonic strategies were not associated with ability-related differences in recall or organization. Some features of memory development are more dependent on age, whereas others are more dependent on ability. The latter may be best explained in terms of production inefficiency (Flavell, 1970).