title: Genetic analysis of IQ, processing speed and stimulus-response incongruency effects.
abstract: Psychometric IQ (WAIS-III), onset and peak latency of the lateralized readiness potential (LRP), decision time, and accuracy were assessed during an Eriksen Flanker task in a young (149 families) and in an older (122 families) cohort of twins and their siblings. Stimulus-response incongruency effects were found on all measures of processing speed and accuracy. The effects on the percentages of wrong button presses and too slow (>1,000 ms) responses were larger in the older than in the younger age cohort. Significant heritability was found for processing speed (33-48%), accuracy (41%), and stimulus-response incongruency effects (3-32%). Verbal and performance IQ correlated significantly with stimulus-response incongruency effects on accuracy (-0.22 to -0.39), and this correlation was completely mediated by an underlying set of common genes. It is concluded that measures of the ability to perform well under conditions of stimulus-response incongruency are viable endophenotypes of cognitive ability.
authors.affiliation: Department of Biological Psychology, Vrije Universiteit Amsterdam, van der Boechorststraat 1, 1081 BT Amsterdam, The Netherlands. danielle@psy.vu.nl
authors.forename: D
authors.initials: D
authors.lastname: Posthuma
authors.forename: E J C M
authors.initials: EJ
authors.lastname: Mulder
authors.forename: D I
authors.initials: DI
authors.lastname: Boomsma
authors.forename: E J C
authors.initials: EJ
authors.lastname: de Geus
mesh_terms: D000328:Adult; D000368:Aged; D002540:Cerebral Cortex / Q000502:physiology*; D015331:Cohort Studies; D003265:Contingent Negative Variation / Q000235:genetics*; D003657:Decision Making / Q000502:physiology; D004193:Discrimination Learning / Q000502:physiology; D004292:Dominance, Cerebral / Q000235:genetics / Q000502:physiology; D004569:Electroencephalography; D005260:Female; D006801:Humans; D007360:Intelligence / Q000235:genetics*; D008297:Male; D008875:Middle Aged; D010364:Pattern Recognition, Visual / Q000502:physiology; D011597:Psychomotor Performance / Q000502:physiology; D011930:Reaction Time / Q000235:genetics*; D014429:Twins, Dizygotic / Q000235:genetics*; D014430:Twins, Monozygotic / Q000235:genetics*; D014888:Wechsler Scales