Intact performance on an indirect measure of race bias following amygdala damage.

Recent brain imaging and lesion studies provide converging evidence for amygdala involvement in judgments of fear and trust based on facial expression [Adolphs et al., Nature 393 (1998) 470; Adolphs et al., Neuropsychologia 37 (1999) 1111; Breiter et al., Neuron 17 (1996) 875; Winston et al., Nat. Neurosci. 5 (3) (2002) 277]. Another type of social information apparent in face stimuli is social group membership. Imaging studies have reported amygdala activation to face stimuli of different racial groups [Hart et al., NeuroReport 11 (11) (2000) 2351]. In White American subjects, amygdala activation to Black versus White faces was correlated with indirect, implicit measures of racial evaluation [Phelps et al., J. Cogn. Neurosci. 12 (5) (2000) 729]. To determine if the amygdala plays a critical role in indirect social group evaluation, as suggested by the imaging results, a patient with bilateral amygdala damage and control subjects were given two measures of race bias. All subjects were female, White Americans. The Modern Racism Scale (MRS) is a direct, self-report measure of race attitudes and beliefs. The Implicit Association Test (IAT) is an indirect, automatic evaluation task. Performance on the two tasks did not differ between the patient with amygdala damage and control subjects. All subjects showed a pro-Black bias on the direct, explicit measure of race beliefs, the MRS, and a negative evaluation towards Black faces on the indirect measure of race evaluation, the IAT. These results indicate that even though amygdala activation to Black versus White faces is correlated with performance on indirect measures of race bias [Phelps et al., J. Cogn. Neurosci. 12 (5) (2000) 729], the amygdala is not critical for normal performance on the IAT.