The influence of expertise on essence beliefs for mental and medical disorder categories.

Research suggests that expertise in a specific category domain influences categorization. Work related to beliefs about mental disorders finds that laypeople treat mental disorders as if they do have causal essences, while clinicians do not-differences that may be attributable to expertise (Ahn, Flanagan, Marsh, & Sanislow, 2006). To test whether reduced beliefs in essences are indicative of an overall influence of expertise or a demonstration of a phenomenon specific to expertise in the mental health domain we compared beliefs about mental and medical disorders held by practicing physicians (n = 43; 19 primary care and 24 non-psychiatry specialists) and laypeople (n = 40). We found differences between these groups in beliefs held concerning the necessity of removing shared category features to effectively cure disorders. While laypeople endorsed the idea that the cause needed to be removed to cure both mental and medical disorders, this endorsement decreased with expertise. Primary care providers were less willing to endorse this for mental disorders than for medical disorders. Our results support the notion that the reduction of beliefs concerning the existence of essences is a unique effect of expertise in the mental health domain, and does not extend to other areas of expertise. In physicians, this reduction of essentialist beliefs was most evident in questions regarding treatment. Similarities and differences to the results from Ahn et al. (2006) are discussed.