Researchers have attempted to understand the behavioral expression of these polymorphisms in different ways; some emphasize behaviors such as impulsive (but not planned) aggression and others focus on disorders such as alcohol dependence (Davidson et al., 2000; Noble, 2003). From our point of view, each of these putative behavioral phenotypes can occur as an expression of emotion-based rash action. It therefore seems possible that these gene polymorphisms, perhaps through their influence on neurotransmitter levels, contribute to individual differences in the urgency traits.
