It has been reported that the ability to solve syllogisms is highly "g"-loaded. In the present study, using a self-administered shortened version of a syllogism-solving test, the "BAROCO Short," we examined whether robust findings generated by previous research regarding IQ scores were also applicable to "BAROCO…

In a population-based sample of 112 nine-year old twin pairs, we investigated the association among total brain volume, gray matter and white matter volume, intelligence as assessed by the Raven IQ test, verbal comprehension, perceptual organization and perceptual speed as assessed by the Wechsler Intelligence Scale for Children-III. Phenotypic…

We studied the age-related differences in inspection time and multiple cognitive domains in a group of monozygotic (MZ) and dizygotic (DZ) twins aged 7 to 17 years. Data from 111 twin pairs and 19 singleton siblings were included. We found clear age-related trends towards more efficient visual information processing in older participants. There…

Studied the extent to which inspection time (IT) relates to psychometric intelligence through general intelligence or through group factors and examined whether IT relates to psychometric intelligence independent from other elementary cognitive tasks. Results for 569 twins aged 6 to 13 years suggest that IT and other elementary tasks predict…

Studied whether genetic variability explained some of the variance in coincidence timing and whether common genetic factors accounted for the association with intellectual functioning using 55 pairs of 16-year-old twins. Results suggest that the genetic influence operating on coincidence timing skills was of similar magnitude to that of response…

Used the classical twin design with 390 pairs of twins to study the influence of genetic factors on the large phenotypic variation in inspection time (IT) and whether the well-established IT-IQ association could be explained by a common genetic factor. Findings provide potentially important information for the biological bases of the…

Hierarchical factor analyses involving Schmid-Leiman transformations were conducted on specific cognitive abilities data collected from 148 identical and 135 fraternal twin pairs from the Western Reserve Twin Project. Model fitting results reflect genetic influences on specific abilities and suggest that environmental influences are less…

Examined the relationship between elementary cognitive tasks and the general factor of intelligence ("g") through tests administered to 568 elementary school students in a study of twins. Findings indicate a memory processing component in addition to a general information processing component contributing to "g" estimates. (SLD)

A battery of information processing measures and psychometric tests of specific and general cognitive abilities was administered to 34 monozygotic and 13 dizygotic reared apart twin pairs or triplets. Correlations between information processing parameters and psychometric abilities as well as twin resemblances for the information processing…

Administered 2 elementary cognitive task (ECT) tests and 2 psychometric intelligence tests to 169 monozygotic and 131 dizygotic pairs of twins in Germany. Reaction times correlated negatively with psychometric intelligence, and habitability estimates were substantial for both psychometric intelligence and reaction times on the ECTs. Multivariate…

Sources of continuity among nine measures of infant cognitive processing and later childhood intelligence quotient were examined through developmental structural equation models applied to a sample of 208 twin pairs measured from 7 to 36 months. Skills assessed appear related to general cognitive ability in a relatively unstable manner. (SLD)