Have you ever gone to the doctor for an injury, but were told it was just minor and there was nothing they could do for you, yet you seemed to be in less pain afterwards? If you have, you're not alone. Although you may not have received any treatment, the pain may have seemed less intense than before seeing the doctor. This can be explained by a phenomenon called retrospective rewriting of the past. Since you were expecting to feel better after seeing the doctor, your memory of the pain before arriving changes to make it seem like the pain was worse before. However, you may be fooling yourself into believing you got better after seeing a doctor.
Some people treated with psychotherapies have similar experiences. It is interesting how people can trick themselves into believing they have improved and therapy worked, when in reality it did not. Understanding this phenomenon is important for therapists in deciding which therapies are effective and which ones are not.