Therapy Outcome Studies
Among the most carefully conducted research on personality change have been studies of various psychotherapies and the effects they bring about.
Psychologists have been interested in the effects of psychotherapy from its inception, and psychotherapy outcome studies began in earnest with research in psychoanalytic institutes (institutes in which practitioners were trained to conduct psychodynamic psychotherapy, on the model of Sigmund Freud). Outcome research increased with the advent of Carl Roger's client-centered psychotherapy. Rogers encouraged the recording of psychotherapy sessions, and the researching of psychotherapy process and its effects.
Research in therapy outcome took on a new urgency in the 1960's and 1970's with the advent of insurance reimbursement for psychotherapy (and the omission of insurance coverage for psychotherapy in many policies because of its apparent expense and uncertain effects).
Beginning in the 1970's a series of sophisticated analyses of prior research on clinical therapy outcome were conducted. The absolutely key study was one by Smith and Glass (1977) which reanalyzed the data of 375 controlled evaluations of psychotherapy that had been conducted to that date. Smith and Glass concluded that psychotherapy did work better than a variety of alternatives, including no-treatment, or being on a waiting list for psychotherapy. Some techniques worked better than others, although the differences among them were slight. In particular, psychodynamic and cognitive-behavioral approaches were especially good at bringing about personality change.
A mini-industry then sprang up, reanalyzing Smith and Glass's work, and adding to it (e.g., Andrews & Harvey, 1981; Brown, 1987; Smith, 1982). One of the key issues concerned which type of psychotherapy worked best. The general upshot of this is that Smith and Glass's original findings have been mostly supported: That is, there is little difference among the most developed forms of psychotherapy. This is sometimes called the "Dodo bird effect," for the portion of Alice's Adventures in Wonderland in which Alice holds a rather disorganized race among the creatures in Wonderland. At the conclusion, the creatures ask the Dodo bird who won. The bird replies, "All have won and all must have prizes." For more on this debate, read Wampold et al.'s (1997) work on the Dodo bird effect (click here). For more fun, read Alice's Adventures in Wonderland.
What Parts of Personality Change?
Despite the great strides that have taken place in clinical therapy outcome research, research on personality change has only just begun. Consider the above research on personality and its change. A considerable number of mysteries remain. For example, if personality is an articulated system -- that is, if personality is a system of broad psychological systems that operate together: motives and emotions, knowledge, self-regulation, and social action -- then do all the parts of personality change with psychotherapy or just some? To date, most measures of therapy outcome have been "non-specific," that is, they examine the general well-being of the therapy client. This is very important for the client, obviously. For the scientist, however, who wishes to improve the effects of therapy, it may not be sufficient.
Psychologists recognize that the techniques they use to change personality may differentially affect some parts of personality moreso than others. For example, in one study, psychologists were asked to assign techniques that are used to change personality to the areas of personality those techniques target. As an example, "changing a person's thoughts about how the world works" would be expected to change cognition, whereas "role-playing new behavior," would be more likley to change a person's planning for social action. The results of the study indicated that psychologists could agree as to which techniques influenced which parts of personality (Mayer, 2004).
Although this seems to be true, there is, as of yet, no research on such differential effects of therapy on personality. It is possible that if such change techniques were better targeted to particular areas of personality, and more specifically measured, that personality change could be brought about more quickly and more effectively than today.
References
Andrews, G., Harvey, R. (1981). A reanalysis of the Smith, Glass, and Miller data. Archives of General Psychiatry, 38, 1203-1208.
Brown, J. (1987). A review of meta-analyses conducted on psychotherapy outcome research. Clinical Psychology Review, 7, 1-23.
Mayer, J. D. (2004). How does psychotherapy influence personality? A theoretical integration. Journal of Clinical Psychology, 60, 1291-1315.
Smith, M. L. (1982). What research says about the effectiveness of psychotherapy. Hospital and Community Psychiatry, 33, 457-461.
Smith, M. L., & Glass, G. V. (1977). Meta-analysis of psychotherapy outcome studies. American Psychologist, 32, 752-780.
Wampold, B. E., Mondin, G. W., Moody, M., Stich, F. Benson, K., Ahn, H.-N. (1997). A meta-analysis of outcome studies comparing bona fide psychotherapies: Empirically, "All must have prizes." Psychological Bulletin, 122, 203-215.