In 1980 Elizabeth and Geoffrey Loftus published a notable paper in the American Psychologist about the permanence of memories. Everything we learn is permanently stored in the mind, although sometimes particular details are not accessible. With hypnosis, or other special techniques, these inaccessible details could eventually be recovered. Some details that we learn may be permanently lost from memory. Such details would never be able to be recovered by hypnosis, or any other special technique, because these details are simply no longer there.
Memory storage is dynamic.
Recall of past experiences and learning is reconstructed through the filter of the present retrieval environment. Remembering an event can change the representation of that event in memory. He likened the psychoanalyst to an archaelogist whose dig was human memory. The task of the therapist was to uncover deeper and deeper layers of memory using the tool of free association. The core idea is that memory representations, once formed, do not get changed by subsequent events, and a therapist can uncover the reminiscences that patients suffer from to release them from their psychological torment.