Despite the emphasis on using objective measures to diagnose mental disorders, a study involving 35 clinicians and 25 clinical trainees showed that theoretical beliefs appear to play a strong role in the process. Both clinicians and trainees held complicated theories about various disorders—including schizophrenia, major depression, anorexia nervosa, and a variety of personality disorders.They also held individual theories about the relative importance of various symptoms, according to a report in the Journal of Experimental Psychology. These theories influenced the diagnoses that the clinicians made when given hypothetical cases. The findings showed that “clinicians are significantly more likely to diagnose patients with a mental disorder when the person exhibits symptoms that are central in the clinician’s own theories of the disorder,” said lead author Woo-kyoung Ahn.