The Effects of Psychotherapy: An EvaluationH. J. Eysenck

Institute of Psychiatry, Maudsley HospitalUniversity of London

The recommendation of the Committee onTraining in Clinical Psychology of the Ameri-can Psychological Association regarding thetraining of clinical psychologists in the field ofpsychotherapy has been criticized by the writerin a series of papers [10, 11, 12]. Of thearguments presented in favor of the policy ad-vocated by the Committee, the most cogent oneis perhaps that which refers to the social needfor the skills possessed by the psychotherapist.In view of the importance of the issues in-volved, it seemed worth while to examine theevidence relating to the actual effects of psy-chotherapy, in an attempt to seek clarificationon a point of fact.

Base Line and Unit of MeasurementIn the only previous attempt to carry out

such an evaluation, Landis has pointed out that"before any sort of measurement can be made,it is necessary to establish a base line and acommon unit of measure. The only unit ofmeasure available is the report made by thephysician stating that the patient has recovered,is much improved, is improved or unimproved.This unit is probably as satisfactory as any typeof human subjective judgment, partaking ofboth the good and bad points of such judg-ments" [26, p. 156.] For a unit Landissuggests "that of expressing therapeutic re-sults in terms of the number of patients re-covered or improved per 100 cases admitted tothe hospital." As an alternative, he suggests"the statement of therapeutic outcome for somegiven group of patients during some stated in-terval of time."

Landis realized quite clearly that in order toevaluate the effectiveness of any form oftherapy, data from a control group of nontreat-ed patients would be required in order to com-pare the effects of therapy with the spontaneousremission rate. In the absence of anything bet-

ter, he used the amelioration rate in statemental hospitals for patients diagnosed underthe heading of "neuroses." As he points out:

There are several objections to the use of theconsolidated amelioration rate . . . of the . . .state hospitals . . . as a base rate for spontaneousrecovery. The fact that psychoneurotic cases arenot usually committed to state hospitals unless in avery bad condition; the relatively small numberof voluntary patients in the group; the fact thatsuch patients do get some degree of psychotherapyespecially in the reception hospitals; and the prob-ably quite different economic, educational, and so-cial status of the State Hospital group compared tothe patients reported from each of the other hospi-tals—all argue against the acceptance of [this] fig-ure . . . as a truly satisfactory base line, but in theabsence of any other better figure this must serve[26, p. 168].

Actually the various figures quoted by Land-is agree very well. The percentage of neuroticpatients discharged annually as recovered orimproved from New York state hospitals is 70(for the years 1925-1934); for the UnitedStates as a whole it is 68 (for the years 1926to 1933). The percentage of neurotics dis-charged as recovered or improved within oneyear of admission is 66 for the United States(1933) and 68 for New York (1914). Theconsolidated amelioration rate of New Yorkstate hospitals, 1917-1934, is 72 per cent. Asthis is the figure chosen by Landis, we may ac-cept it in preference to the other very similarones quoted. By and large, we may thus saythat of severe neurotics receiving in the maincustodial care, and very little if any psycho-therapy, over two-thirds recovered or improvedto a considerable extent. "Although this is not,strictly speaking, a basic figure for 'spontane-ous' recovery, still any therapeutic methodmust show an appreciably greater size than thisto be seriously considered" [26, p. 160].

Another estimate of the required "baseline" is provided by Denker:

319

320 H. J. Eysenck

Five hundred consecutive disability claims due topsychoneurosis, treated by general practitionersthroughout the country, and not by accredited spe-cialists or sanatoria, were reviewed. All types ofneurosis were included, and no attempt made todifferentiate the neurasthenic, anxiety, compulsive,hysteric, or other states, but the greatest care wastaken to eliminate the true psychotic or organiclesions which in the early stages of illness so oftensimulate neurosis. These cases were taken consec-utively from the files of the Equitable Life Assur-ance Society of the United States, were from allparts of the country, and all had been ill of a neu-rosis for at least three months before claims weresubmitted. They, therefore, could be fairly called"severe," since they had been totally disabled for atleast a three months' period, and rendered unable tocarry on with any "occupation for remuneration orprofit" for at least that time [9, p. 2164].

These patients were regularly seen andtreated by their own physicians with sedatives,tonics, suggestion, and reassurance, but in nocase was any attempt made at anything butthis most superficial type of "psychotherapy"which has always been the stock-in-trade of thegeneral practitioner. Repeated statements,every three months or so by their physicians,as well as independent investigations by the in-surance company, confirmed the fact that thesepeople actually were not engaged in produc-tive work during the period of their illness.During their disablement, these cases receiveddisability benefits. As Denker points out, "Itis appreciated that this fact of disability incomemay have actually prolonged the total periodof disability and acted as a barrier to incentivefor recovery. One would, therefore, not expectthe therapeutic results in such a group of casesto be as favorable as in other groups where theeconomic factor might act as an important spurin helping the sick patient adjust to his neuroticconflict and illness" [9, p. 2165].

The cases were all followed up for at leasta five-year period, and often as long as tenyears after the period of disability had begun.The criteria of "recovery" used by Denkerwere as follows: (a) return to work, andability to carry on well in economic adjust-ments for at least a five-year period; (£) com-plaint of no further or very slight difficulties;(e) making of successful social adjustments.Using these criteria, which are very similar tothose usually used by psychiatrists, Denkerfound that 45 per cent of the patients recovered

after one year, another 27 per cent after twoyears, making 72 per cent in all. Another 10per cent, 5 per cent, and 4 per cent recoveredduring the third, fourth, and fifth years, re-spectively, making a total of 90 per cent re-coveries after five years.

This sample contrasts in many ways withthat used by Landis. The cases on whichDenker reports were probably not quite assevere as those summarized by Landis; theywere all voluntary, nonhospitalized patients,and came from a much higher socioeconomicstratum. The majority of Denker's patientswere clerical workers, executives, teachers, andprofessional men. In spite of these differences,the recovery figures for the two samples arealmost identical. The most suitable figure tochoose from those given by Denker is probablythat for the two-year recovery rate, as follow-up studies seldom go beyond two years andthe higher figures for three-, four-, and five-year follow-up would overestimate the effi-ciency of this "base line" procedure. Using,therefore, the two-year recovery figure of 72per cent, we find that Denker's figure agreesexactly with that given by Landis. We may,therefore, conclude with some confidence thatour estimate of some two-thirds of severeneurotics showing recovery or considerable im-provement without the benefit of systematicpsychotherapy is not likely to be very far out.

Effects of PsychotherapyWe may now turn to the effects of psycho-

therapeutic treatment. The results of nineteenstudies reported in the literature, covering overseven thousand cases, and dealing with bothpsychoanalytic and eclectic types of treatment,are quoted in detail in Table 1. An attempthas been made to report results under the fourheadings: (a) Cured, or much improved; ( b )Improved; (c) Slightly improved; (d) Notimproved, died, discontinued treatment, etc.It was usually easy to reduce additional cate-gories given by some writers to these basicfour; some writers give only two or three cate-gories, and in those cases it was, of course, im-possible to subdivide further, and the figuresfor combined categories are given.1 A slight

aln one or two cases where patients who im-proved or improved slightly were combined by theoriginal author, the total figure has been dividedequally between the two categories.

The Effects of Psychotherapy 321

Table 1Summary of Reports of the Results of Psychotherapy

(A) Psychoanalytic1. Fenichel [13, pp. 28-40]2. Kessel & Hyman [24]3. Jones [22, pp. 12-14]4. Alexander [1, pp. 30-43]5. Knight [25]

All cases

(B) Eclectic1. Huddleson [20]2. Matz [30]3. Maudsley Hospital

Report (1931)4. Maudsley Hospital

Report (1935)5. Neustatter [32]6. Luff & Garrod [27]7. Luff & Garrod [27]8. Ross [34]9. Yaskin [40]

10. Curran [7] ..11. Masserman &

Carmichael [29]12. Carmichael &

Masserman [4]..13. Schilder [35]14. Hamilton & Wall [16]15. Hamilton £i al. [15] .16. Landis [26]17. Institute Med. Psychol.

(quoted Neustatter)18. Wilder [39]19. Miles et al. ([31]

All cases

N

4843459

14142

760

200775

1721

171146

500210

108910083

50

7735

100100119

2705453

7293

Cured ;muchim-

proved

104162028

g

335

1910

288

3719

14038

54729

51

7

1611324840

583

13

4661

Im-proved

8458

4220

74310

900

76514

13584

30629

20

251134

547

1322418

Slightlyim-

proved

994

2823

7

425

80310

533

5758

2654

2364232

5

146

1717

32

551613

2632

Notim-

proved ;died;left

treat-ment

19793

487

27145

1519934

18

227

1732

25Ha

%Cured;much

im-proved ;

im-proved

3962475067

44%

4641

69

64505568775861

54

5363665173

705058

64%

degree of subjectivity inevitably enters into thisprocedure, but it is doubtful if it has causedmuch distortion. A somewhat greater degreeof subjectivity is probably implied in thewriter's judgment as to which disorders anddiagnoses should be considered to fall underthe heading of "neurosis." Schizophrenic,manic-depressive, and paranoid states havebeen excluded; organ neuroses, psychopathicstates, and character disturbances have been in-cluded. The number of cases where there was

genuine doubt is probably too small to makemuch change in the final figures, regardless ofhow they are allocated.

A number of studies have been excluded be-cause of such factors as excessive inadequacyof follow-up, partial duplication of cases withothers included in our table, failure to indicatetype of treatment used, and other reasonswhich made the results useless from our pointof view. Papers thus rejected are those byThorley & Craske [37], Bennett and Semrad

322 H. J. Eytenck

[2], H. I. Harris [19], Hardcastle [17], A.Harris [18], Jacobson and Wright [21],Friess and Nelson [14], Comroe [5], Wenger[38], Orbison [33], Coon and Raymond [6],Denker [8], and Bond and Braceland [3].Their inclusion would not have altered ourconclusions to any considerable degree, al-though, as Miles et al. point out: "When thevarious studies are compared in terms ofthoroughness, careful planning, strictness ofcriteria and objectivity, there is often an in-verse correlation between these factors and thepercentage of successful results reported" [31,p. 88].

Certain difficulties have arisen from the in-ability of some writers to make their columnfigures agree with their totals, or to calculatepercentages accurately. Again, the writer hasexercised his judgment as to which figures toaccept. In certain cases, writers have givenfigures of cases where there was a recurrenceof the disorder after apparent cure or im-provement, without indicating how many pa-tients were affected in these two groups re-spectively. All recurrences of this kind havebeen subtracted from the "cured" and "im-proved" totals, taking half from each. Thetotal number of cases involved in all these ad-justments is quite small. Another investigatormaking all decisions exactly in the oppositedirection to the present writer's would hardlyalter the final percentage figures by more than1 or 2 per cent.

We may now turn to the figures as present-ed. Patients treated by means of psychoanaly-sis improve to the extent of 44 per cent; pa-tients treated eclectically improve to the extentof 64 per cent; patients treated only custodiallyor by general practitioners improve to the ex-tent of 72 per cent. There thus appears to bean inverse correlation between recovery andpsychotherapy; the more psychotherapy, thesmaller the recovery rate. This conclusion re-quires certain qualifications.

In our tabulation of psychoanalytic results,we have classed those who stopped treatmenttogether with those not improved. This ap-pears to be reasonable; a patient who fails tofinish his treatment, and is not improved, issurely a therapeutic failure. The same rulehas been followed with the data summarizedunder "eclectic" treatment, except when the

patient who did not finish treatment was defi-nitely classified as "improved" by the therapist.However , in view of the peculiarities ofFreudian procedures it may appear to somereaders to be more just to class those casesseparately, and deal only with the percentageof completed treatments which are successful.Approximately one-third of the psychoanalyticpatients listed broke off treatment, so that thepercentage of successful treatments of patientswho finished their course must be put at ap-proximately 66 per cent. It would appear,then, that when we discount the risk the pa-tient runs of stopping treatment altogether, hischances of improvement under psychoanalysisare approximately equal to his chances of im-provement under eclectic treatment, and slight-ly worse than his chances under a generalpractitioner or custodial treatment.

Two further points require clarification:(a) Are patients in our "control" groups(Landis and Denker) as seriously ill as thosein our "experimental" groups? ( b ) Arestandards of recovery perhaps less stringent inour "control" than in our "experimental"groups ? It is difficult to answer these questionsdefinitely, in view of the great divergence ofopinion between psychiatrists. From a closescrutiny of the literature it appears that the"control" patients were probably at least asseriously ill as the "experimental" patients, andpossibly more so. As regards standards of re-covery, those in Denker's study are as stringentas most of those used by psychoanalysts andeclectic psychiatrists, but those used by theState Hospitals whose figures Landis quotesare very probably more lenient. In the absenceof agreed standards of severity of illness, or ofextent of recovery, it is not possible to go fur-ther.

In general, certain conclusions are possiblefrom these data. They fail to prove that psy-chotherapy, Freudian or otherwise, facilitatesthe recovery of neurotic patients. They showthat roughly two-thirds of a group of neuroticpatients will recover or improve to a markedextent within about two years of the onset oftheir illness, whether they are treated by meansof psychotherapy or not. This figure appearsto be remarkaby stable from one investigationto another, regardless of type of patient treated,standard of recovery employed, or method of

The Effects of Psychotherapy 323

therapy used. From the point of view of theneurotic, these figures are encouraging; fromthe point of view of the psychotherapist, theycan hardly be called very favorable to hisclaims.

The figures quoted do not necessarily dis-prove the possibility of therapeutic effective-ness. There are obvious shortcomings in anyactuarial comparison and these shortcomingsare particularly serious when there is so littleagreement among psychiatrists relating evento the most fundamental concepts and defini-tions. Definite proof would require a specialinvestigation, carefully planned and method-ologically more adequate than these ad hoccomparisons. But even the much more modestconclusions that the figures fail to show anyfavorable effects of psychotherapy should givepause to those who would wish to give an im-portant part in the training of clinical psy-chologists to a skill the existence and effective-ness of which is still unsupported by any sci-entifically acceptable evidence.

These results and conclusions will no doubtcontradict the strong feeling of usefulness andtherapeutic success which many psychiatristsand clinical psychologists hold. While it istrue that subjective feelings of this type haveno place in science, they are likely to preventan easy acceptance of the general argumentpresented here. This contradiction betweenobjective fact and subjective certainty has beenremarked on in other connections by Kelly andFiske, who found that "One aspect of our find-ings is most disconcerting to us: the inverserelationship between the confidence of staffmembers at the time of making a prediction andthe measured validity of that prediction. Whyis it, for example, that our staff members tend-ed to make their best predictions at a time whenthey subjectively felt relatively unacquaintedwith the candidate, when they had constructedno systematic picture of his personality struc-ture? Or conversely, why is it that with in-creasing confidence in clinical judgment. .. wefind decreasing validities of predictions?" [23,p. 406].

In the absence of agreement between factand belief, there is urgent need for a decreasein the strength of belief, and for an increasein the number of facts available. Until suchfacts as may be discovered in a process of rigor-

ous analysis support the prevalent belief intherapeutic effectiveness of psychological treat-ment, it seems premature to insist on the in-clusion of training in such treatment in thecurriculum of the clinical psychologist.

SummaryA survey was made of reports on the im-

provement of neurotic patients after psycho-therapy, and the results compared with the bestavailable estimates of recovery without benefitof such therapy. The figures fail to supportthe hypothesis that psychotherapy facilitates re-covery from neurotic disorder. In view of themany difficulties attending such actuarial com-parisons, no further conclusions could be de-rived from the data whose shortcomings high-light the necessity of properly planned andexecuted experimental studies into this im-portant field.Received January 23, 1952.

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