The proclivity to choose actions that lead to immediate gratification, at the expense of other – arguably more rational and optimal – behaviors is thought to reflect a distinct aspect of impulsivity than do phenotypes linked with impulsive action. The preceding section dealt with the relationship between delay discounting and substance abuse behaviors, as well as the underlying neural circuitry and neuropharmacological mechanisms that mediate this form of impulsive choice. While differences in mechanism between inhibitory response control and delay discounting have been reported, it is also clear that the two dimensions of impulsivity share, at least in part, biological influences. The next section will add to this comparison by considering yet another conceptually distinctive dimension of impulsivity related to risk assessment, preference and aversion.
