“…For example, in a longitudinal sample of children, self-report positive affectivity was related to feedback negativity (i.e., activation in the ventral striatum and medial prefrontal cortex in monetary loss trials minus activation in gain trials) in a hierarchical regression model controlling for demographic covariates and negative affectivity, but not at the bivariate level (r = â.09; N = 381; Kujawa et al, 2015). In adult samples, there is some recent evidence that reward-processing (i.e., activation in medial frontal regions during unpredicted reward trials minus unpredicted non-reward trials) is uniquely positively related to Extraversion (r = .26; N = 100; Smillie et al, 2019), but other studies have not found support for this relation (r = .06; N = 371; Suzuki, Hill, Ait Oumeziane, Foti, & Samuel, 2019). In terms of functional neuroimaging methodology, there are numerous studies linking Extraversion to dopaminergic reward regions like the ventral striatum (Canli, Sivers, Whitfield, Gotlib, & Gabrieli, 2002;Canli et al, 2001;Cohen, Young, Baek, Kessler, & Ranganath, 2005;Mobbs, Hagan, Azim, Menon, & Reiss, 2005;Schaefer, Knuth, & Rumpel, 2011;Wu, Samanez-Larkin, Katovich, & Knutson, 2014), but virtually all of the previous work on Extraversion and fMRI reward-processing was statistically underpowered, with most studies using samples under 20 participants.…”