“…In recent years there has been increasing recognition that psychopathic traits are not binary phenomena, and psychopathy can also refer to a spectrum of affective ('primary') and antisocial ('secondary') psychopathic traits associated with the personality disorder, but present to a lesser degree across the population 4,[29][30][31] (but see 32 ). Finally, the core callous-unemotional affective traits of psychopathy (low empathy, shallow affect, remorselessness, and lack of concern about performance in important activities) are now used to demarcate a more severe 'limited prosocial emotions' subtype of conduct disorder in the DSM-5 9,[33][34][35][36][37][38] , although callous-unemotional traits are not binary phenomena and are typically somewhat elevated in conduct disorder regardless of subtype 39 (Figure 1). Similar phenomena are therefore described using different terminology in children and adults, a situation that is perhaps compounded by the tendency for most researchers to specialise in only one developmental period.…”