Although the undercontrol/disinhibition characterization makes the best sense, the umbrella it covers is a large one. The jury is still out about whether this will remain the best superordinate characterization, whether the domain should include all of the component pieces described above, and whether such a superordinate level of analysis is most effective for identifying liability. A number of other groups are actively exploring these issues: two (Smith et al., 2007; Dick et al., 2010) are focused on parsing the impulsivity construct, albeit in different ways; a third proposes a composite indicator of neurobehavioral disinhibition that cuts across behavioral, neuropsychological, and affective domains (Tarter et al., 2003); a fourth proposes that the core liability trait is one of behavioral disinhibition, indexed behaviorally by externalizing symptomatology, but also neurophysiologically via brain P300 response (see Iacono & Malone, 2011; Iacono, Malone, & McGue, 2008); a fifth, which proposes that the core liability is one of behavioral undercontrol, delineates a personality structure virtually identical to that in Iacono et al.'s (2008) behavioral disinhibition construct but focuses more on personality structure and genetic basis
