Traumatic memories are more likely to be “forgotten” than non-traumatic memories due to faulty encoding or retrieving. A major mental process contributing to amnesia in dissociative disorders is known as state-dependant learning. According to this theory, information encoded in one mental state is most easily retrieved at a later time when in that same state. If a person experiencing trauma dissociates into separate state of mind, different memories will become available to that person at different times. Data encoded in one state will not be available to a person who is in a different psychological state; it will only be available when the person returns to the same state he/she was in at the time when it was encoded. For example: Harris, a thirty-seven-year-old pharmacist who was sexually abused repeatedly throughout his childhood by an older cousin, developed a six-year-old alternative personality named Barney. Harris could not remember the abuse until an assault by an armed robber at the drugstore where he worked triggered Barneys return.
State-dependent learning theory explains the severe amnesia that occurs in DID. Experiences encoded in a psychological state of abuse can chain together into a complex and consistent personality if the abuse is sufficiently traumatic and persistent. These particular alert personalities of overwhelming pain and fear are outside the persons conscious cognitive awareness, they live on in an alter personality and are still psychologically active and influential.
The “lost time” or “memory gaps” of someone with DID have preserved their sanity but have also swallowed up vast chunks of their past and identity. The future of a person with amnesia can be compromised too. The inability to integrate traumatic memories caused the person to fixate art the time of the trauma and impairs the integration of new experiences. When Barney resurfaces Harris was unable to concentrate on his job as a pharmacist and fill prescriptions that were beyond the comprehension of a six-year-old child. For many people, traces of the painful memory tend to linger and intrude as flashbacks, obsessions, or re-enactments of the trauma in self-mutilation or other self-destructive behaviours.