The concept of general intelligence ("g") summarizes the well established finding that scores on separate cognitive tasks are positively correlated, indicating a trait common to many aspects of information processing. Inspection time is a well-established correlate of IQ, where those of a higher IQ can correctly identify a briefly…

Self-perceived abilities (SPA), which play an important role in academic achievement, have been recently reported to be fully attributable to genetic and non-shared environmental influences. To replicate and extend this finding, 732 Croatian twins (15-22 years old) were assessed on cognitive ability, self-assessed intelligence (SAI), and Five…

There is increasing evidence relating psychometric measures of general intelligence and reasoning to regional brain structure and function assessed with a variety of neuroimaging techniques. Cognitive dimensions independent of general intelligence can also be identified psychometrically and studied for any neuroanatomical correlates. Here we…

Whether IQ level exerts a differential effect on the impairment of cognitive performance induced during acute hypoglycemia was studied for 24 nondiabetic adults. At various levels of hypoglycemia, no overall effect of IQ on deterioration was noted. Higher IQ did not apparently protect against adverse effects. (SLD)

Using a simple neural model comprising between two and four neurons, it is concluded that speed of neuron conduction is not the probable basis of the intelligence quotient (IQ)-reaction time (RT) correlation. This result illustrates that neural modeling can be applied to biological theories of individual differences in intelligence. (SLD)

The author replies to Jensen and Vernon's article and maintains that there is little reason for accepting Jensen's claims, particularly with respect to the major theoretical question. (Author/LMO)

Prior studies found individual differences in visual recognition memory during infancy were related to individual differences in later intelligence. This paper discusses methodological issues in the measurement of infant visual recognition, the significance of previously obtained predictive validity coefficients, and the theoretical question of…

Data from the national standardization of the French version of the WISC-III were analyzed to determine when during childhood the IQ-related process of differentiation appears and how the strength of the relationships among subtests evolves with age in low- and high-IQ groups. Indeed, some recent studies suggest that age might moderate the effect…

Mildly retarded young adults were given simple and choice reaction time (RT) tests. Subjects' RTs increased with stimulus complexity. RTs of retarded subjects were slower and evidenced more intraindividual variability than those of nonretarded subjects. Several RT parameters were related to measures of intelligence. (Author/RD)

To study whether individual differences in general cognitive ability differ in males and females, full-scale IQ data from 426 child twin pairs were fitted to a structural equation model of sex limitation. Individual differences in general cognitive ability appear to be substantially due to common genetic influences in males and females. (SLD)

A large number of national and geographic population samples were used to test the hypothesis that the variation in mean values of skin color in the diverse populations are consistently correlated with the mean measured or estimated IQs of the various groups, as are some other physical variables, known as an ecological correlation. Straightforward…

The authors discuss methodological and theoretical issues in psychological investigations of infant attention, fixation times, habituation, and intelligence. A consensus on how to measure individual differences in habituation has not been reached. The relation between IQ and attention is discussed. (RD)

Four points are made in regard to the controversial reaction times studies: (1) apparatus used is not the best; (2) practice effects have not been thoroughly accounted for; (3) there is some evidence that simple reactions are different from choice ones; and (4) basic data to be explained are those which show substantial group differences.…

This editorial proposes that the dependent variables that predict childhood intelligence quotient (IQ) from habituation and recognition memory assessments made during infancy may primarily reflect individual differences in rate of information processing. Inhibition may be a stable thread in mental development. (Author/SLD)

Two experiments examined whether correlations between IQ and probed serial running memory depend on IQ-related individual differences in the retention of order information in short-term memory. Children's IQ correlated with memory, regardless of whether instructions emphasized serial or free recall; and with recent item but not recent order…