Genetic sources of covariation among P3(00) and online performance variables in a delayed-response working memory task.

Genetic and environmental sources of covariation among the P3(00) and online performance elicited in a delayed-response working memory task, and psychometric IQ assessed by the multidimensional aptitude battery, were examined in an adolescent twin sample. An association between frontal P3 latency and task performance (phenotypic r=-0.33; genotypic r=-0.49) was indicated, with genes (i.e. twin status) accounting for a large part of the covariation (>70%). In contrast, genes influencing P3 amplitude mediated only a small part (2%) of the total genetic variation in task performance. While task performance mediated 15% of the total genetic variation in IQ (phenotypic r=0.22; genotypic r=0.39) there was no association between P3 latency and IQ or P3 amplitude with IQ. The findings provide some insight into the inter-relationships among psychophysiological, performance and psychometric measures of cognitive ability, and provide support for a levels-of-processing genetic model of cognition where genes act on specific sub-components of cognitive processes.