Visual search: Heritability and association with general intelligence.

Visual search guides goal-directed action in humans and many other species, and it has been studied extensively in the past. Yet, no study has investigated the relative contributions of genes and environments to individual differences in visual search performance, or to which extent etiologies are shared with broader cognitive phenotypes. To address this gap, we studied visual search and general intelligence in 156 monozygotic (MZ) and 158 same-sex dizygotic (DZ) twin pairs. We found that different indexes of visual search performance (response latency and visual search efficiency) were moderately heritable. Phenotypic correlations between visual search and intelligence were small-to-moderate, and only a small proportion of the genetic variance in visual search was shared with genetic variance in intelligence. We discuss these findings in the context of the "generalist genes hypothesis" stating that different cognitive functions have a common genetic basis.