Temperament has been defined as “constitutionally based individual differences in reactivity and self-regulation, in the domains of affect, activity, and attention” (Rothbart & Bates, 2006, p. 100). Self-regulation refers to “processes such as effortful control and orienting that function to modulate reactivity” whereas reactivity refers to “the arousability of motor, affective, and sensory response systems” (Rothbart, Ahadi, Hersey, & Fisher, 2001, p. 1395).
