What is Dissociation
The essential feature of a Dissociative Disorder is a disruption in the usually integrated functions of consciousness, memory, identity, or perception of the environment. The disturbance may be sudden or gradual, transient or chronic. In other words, an event is processed in a way that breaks up the pieces of the event into differing states of consciousness.
Dissociation is common and nearly everyone experiences mild dissociation from time to time. If you have ever had the experience of driving somewhere, and suddenly you realize that you have little or no memory of driving the last few minutes. Perhaps you even passed your exit. Your driving ability wasn't hindered because the mind was still utilizing the part of the brain that was needed to drive the car. However, instead of your thinking-mind focusing on the driving, it was somewhere else. That is dissociation. Daydreaming is a very mild form of dissociation.
On the other end of the dissociation-continuum, dissociation is often a way for the brain to tear apart the sensations, or the memory of a traumatic event in order to survive the situation with as little damage as possible. For instance, the actual memory might be put so far back in the subconscious mind, that it is perceived as being forgotten. However, the body sensations may still be present and may be experienced from time to time as somatic eruptions, body memories. The feelings related to the trauma may be "switched off," generally taking with it the individuals ability to experience other feelings later in life.