What you learned in school
Psychology textbooks presented multiple personality disorder as a fascinating and relatively common mental health condition. Students learned about dramatic cases with dozens of distinct personalities, often through famous case studies like "The Three Faces of Eve" and "Sybil." The condition was portrayed as a clear example of how trauma could fragment the mind into separate identities.
What we know now
Psychology textbooks featured multiple personality disorder (now called dissociative identity disorder) as a relatively common condition. Popular media like "The Three Faces of Eve" and "Sybil" reinforced this perception. Students learned about dramatic cases of people with many distinct personalities. Dissociative identity disorder is extremely rare, and many of the famous cases that made it seem common were later found to be inaccurate or potentially iatrogenic (caused by therapy itself). The condition became overdiagnosed in the 1980s and 1990s, leading to more careful diagnostic criteria and recognition of how suggestion and expectation can influence patient presentations.