Evidence that dissociative identity disorder is NOT simply a product of conscious role playing is most clearly provided by the

A) periodic intervals during which patients with this disorder become violent.
B) distinct brain and body states associated with differing personalities.
C) inability of psychiatric experts to hypnotize patients with this disorder.
D) dramatic increase in reported cases of this disorder during the past 40 or so years.

The distinct brain and body states associated with differing personalities provide compelling evidence that dissociative identity disorder is not simply a product of conscious role playing. Studies using brain imaging technologies have provided evidence of measurable physiological changes that occur when individuals with DID switch between identities, such as changes in brain activity, heart rate, blood pressure, and even eye prescription. These changes are not consistent with conscious role playing and suggest that DID involves a deeper level of dissociation within the individual.