Several impulsivity-related models have been applied to understanding the vulnerability to addiction. While there is a growing consensus that impulsivity is multifaceted, debate continues as to the precise number of facets and, more critically, which are most relevant to explaining the addiction-risk profile. In many ways, the current debate mirrors that which took place in the personality literature (e.g., Eysenck's 'Big Three' versus Costa and McCrae's 'Big Five').Indeed, many elements of this debate are relevant to the current discussion of the role of impulsivity in addictive behavior. Specifically, 1) the use of factor analysis as an atheoretical 'truth-grinding machine'; 2) whether additional facets add explanatory power over fewer; 3) the delineation of specific neurocognitive pathways from each facet to addictive behaviors, and; 4) the relative merit of 'top-down' versus 'bottom-up' approaches to the understanding of impulsivity. Ultimately, the utility of any model of impulsivity and addiction lies in its heuristic value and ability to integrate evidence from different levels of analysis. Here, we make the case that theoretically-driven, bottom-up models proposing two factors deliver the optimal balance of explanatory power, parsimony, and integration of evidence.Keywords: impulsivity, addiction, substance use, alcohol, urgency, UPPS 3
IntroductionImpulsivity, whether measured by self-report, observer-report, or behavioral performance, is a robust predictor of current and future problems with substance use Jentsch & Taylor, 1999;Moeller et al., 2001;Moffitt et al., 2011;Nigg et al., 2006;Potenza, 2013;Tarter et al., 2003). In children, its association with future substance use remains even after controlling for other markers of risk, including low IQ, socioeconomic status, and parental history of substance dependence (Moffitt et al., 2011;Nigg et al., 2006;Tarter et al., 2003). Not surprisingly, the construct is of great interest to addiction scientists.In addiction science, there is an emerging consensus that impulsive drug use involves two core processes observable at the neurophysiological, behavioral, cognitive, and trait. The first involves a heightened propensity or impulse to approach drugs and the second involves a reduced capacity to inhibit this approach behavior. The summary presented in Table 1 highlights the considerable overlap of different theoretical models in the importance placed on these two fundamental processes that have been derived from multiple researchers across diverse methodological investigations.
-----------------------------INSERT TABLE 1 HERE-----------------------------Whilst a two-factor model is attractive in its parsimony, other researchers have proposed that a more useful way to consider impulsivity is to develop a more nuanced delineation of subtypes. This would have important implications for addiction science. In an attempt to "bring order to the myriad of measures and conceptions of impulsivity", Whiteside and Lynam (2001, p. 684) drew upon the Five Factor...
