Individual differences in inspection time explain about 20% of IQ test variance. To determine whether the association between inspection time and IQ is mediated by common genes or by a common environmental factor, inspection time and IQ were assessed in an extended twin design. Data from 688 participants from 271 families were collected as part of a large ongoing project on the genetics of adul...

Now, in its third revision, the Wechsler Adult Intelligence Scale-III has a new factor structure. The theoretical structure of the new instrument is hierarchical in nature and contains four firstorder factors with a second-order g factor at the apex. In addition to the theoretical hierarchical factor structure of the new instrument, there is an implied factor structure that is used for scoring....

BACKGROUND Twin studies have lacked statistical power to apply advanced genetic modelling techniques to the search for cognitive endophenotypes for bipolar disorder. AIMS To quantify the shared genetic variability between bipolar disorder and cognitive measures. METHOD Structural equation modelling was performed on cognitive data collected from 331 twins/siblings of varying genetic relatedn...

Statistical learning is characterized by detection of regularities in one's environment without an awareness or intention to learn, and it may play a critical role in language and social behavior. Accordingly, in this study we investigated the electrophysiological correlates of visual statistical learning in young children with autism spectrum disorder (ASD) using an event-related potential sha...

Intelligence, as measured by standardized psychological tests, has been shown to be highly heritable, though identifying specific genes influencing general intelligence has proven difficult. We conducted genome-wide linkage analyses to identify chromosomal regions containing genes influencing intelligence, as measured by WAIS full-scale IQ (FSIQ), performance IQ (PIQ) and verbal IQ (VIQ). Non-p...

Some researchers have compared neuropsychological performance in schizophrenia groups with and without presumed IQ decline. Inherent in this approach is an assumption that group differences are due to different IQ trajectories (stable vs. declining), but neuropsychological differences could be a function of current IQ regardless of the presence or absence of previous IQ decline. We examined thi...

WAIS-R Verbal-Performance IQ difference scores for Ward's (1990) seven subtest short form and the complete WAIS-R were examined in patients with lateralized and diffuse lesions. For both versions, the expected Performance > Verbal pattern was observed in the right hemisphere lesion group, while no summary score differences were seen in the left hemisphere group. Verbal-Performance IQ discrepanc...

BACKGROUND Efficient memory functions are important to the development of cognitive and functional skills, allowing individuals to manipulate and store information. Theories of memory have suggested the presence of domain-specific (i.e. verbal and spatial) and general processing mechanisms across memory domains, including memory functions dependent on the prefrontal cortex (PFC) and the hippoca...

Fifteen measures of non-verbal communication were coded from videotaped interactions between a female confederate and 18-21 year old female subjects (n = 46). Three measures of extraversion and neuroticism had previously been taken from the subjects, as was a measure of IQ. Correlation and factor analysis revealed significant relationships between certain of the variables. Extraversion was stro...