Dissociation in psychology is an experience that involves a detachment/separation from reality. It is different from psychosis, psychosis is a loss of reality. It can describe many things. The mildest form of it involves things such as daydreaming. A less mild form of it involves altered states of consciousness. This is non-pathological, meaning it is not considered a disorder or mental illness. These forms are often a coping mechanism or defense mechanism. This means that they protect against stress.