A common reason for inability to recall is failure to encode in the first place. Interference Theory Retroactive interference occurs when a new memory interferes with the recall of an older one. There may be cases in which we would like to forget something, such as a trauma. Suppression refers to intentional, conscious, forgetting of information. This may not be possible.
Repression refers to unconscious, but motivated, blocking of memories.
Among researchers, there are those who do not believe that repression occurs as well as those who hold it responsible for a myriad of psychological problems. Still others memory researchers propose that extreme emotion can disrupt memory but believe that the case for repression is far from clear. Decay Theory Decay theory holds that an unused memory trace disappears with time. This is not supported by research that shows that strong cues can brink back old, unused memories. Lashley initially believed that the changes were specific and localized.