Wilbur's diagnosis of Mason has been questioned, and both Flora Schreiber and she have been accused of inventing or exaggerating the multiple personality diagnosis and manipulating Mason for professional and financial gain. One examination of the case of "Sybil" is
Debbie Nathan's book
Sybil Exposed: The Extraordinary Story Behind the Famous Multiple Personality Case. Nathan presented evidence that Mason never displayed multiple personalities until she met Wilbur. The patient's symptoms emerged over the years from a mutually reinforced self-deception of both Mason and Wilbur. Nathan's research indicated that Wilbur and Schreiber fabricated aspects of the treatment narrative in
Sybil to bolster their claims about Mason, even including Mason's father's claim that Mason's mother had been diagnosed with
schizophrenia. People related to Shirley Mason backed up Shirley's diagnosis. Some professionals on dissociative disorders, like
Colin A. Ross, have questioned Nathan's thesis that the real diagnosis was not DID, but
pernicious anemia, which doesn't cause the symptoms —and doesn't disappear during the nine-year period Shirley wasn't in therapy— that Nathan described. Ross acknowledges, however, that Wilbur's treatment "involved massive boundary violations of numerous types over many years". == Appearances ==