The early research on an animal (cat) model and biological marker (visual evoked potential augmenting and reducing) of sensation seeking behavior is briefly described. Recent findings with selectively bred lines of rats show that (1) the relationship between sensation seeking behavior and augmenting vs. reducing is also present in the rat; (2) augmenting and reducing is a cortical, not a subcortical, phenomenon, and (3) augmenting/reducing and related sensation seeking behaviors are heritable traits. This paper also discusses evidence for the relative contributions of genetic and environmental factors in determining the sensation seeking trait.