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Recurring assessment of changes in phobic behavior during the course of systematic desensitization
Behav.
Req.
& Therapy,
1972,
Vol.
IO, pp. 279 to 282.
CASE HISTORIES
Pergamon
Press.
Printed
AND SHORTER
in England
COMMUNICATIONS
Recurring assessment of changes in phobic behavior during the course of systematic desensitization * (Received
13 January
1972)
IN REFERENCE to his therapeutic system of systematic desensitization, Wolpe (1963) found that “there is almost invariably a one-to-one relationship between what the patient can imagine without anxiety and what he can experience m reality without anxiety” (p. 1063). Further, most patients reported gradual improvement in real life to previously fearful situations (or objects) as the result of desensitization (Wolpe, 1961). Wolpe’s findings Imply that as the patient progresses m therapy, there should be corresponding gradual extratherapeutic change or transfer in terms of his ability to deal with the fearful situation. Elsewhere, however, Wolpe (1954, 1966) noted that extratherapeutlc change may lag behind the lessening of anxiety in therapy, suggesting occasional difficulty in transfer. The most common observations of transfer have been made only at the endof a course of desensitization. In some studies, immediate transfer from the imagined to the real situation has been reported (e.g. Rachman, 1966), while in others transfer lagged behind completed desensihzation (Hain ef al., 1966; Meyer and Crisp, 1966). In order to assess this process more directly, Agras (1967), in a clinical study of five agoraphobic patients, tested for transfer during the course of desensitization. Improvement in the feared situation(s) was measured by obtaining self-reports from patients at each desensitization session. One patient’s improvement With the remaining patients behavioral was gradual and closely paralleled progress in desensitization. changes outside of therapy lagged behind the reduction of imaginal anxiety during desensitization, and improvement occurred mainly during the last half of therapy. Thus, a certain degree of progress in desensitization appeared necessary before noticeable clinical change was reported. However, since Agras did not employ an objective behavioral measure, and since controls were lacking, further exploration of transfer during the course of desensitization is needed. Although Lang, Lazovik and Reynolds (1965) did not test for transfer during desensitization, their data also suggested that therapy must be well advanced before effects are clearly evident. Their conclusion was based upon the high positive relationship found between the number of hierarchy items completed during desensitization and various pre-post therapy measures of fear change in an analogue study of snake phobic college students. Of the subjects treated by desensitization, those who completed at least 75 per cent of the hierarchy were found to show significantly greater pre-post improvement on all measures of anxiety and on the behavioral avoidance test than those who completed less than 75 per cent. Further, the less than 75 per cent group did not differ significantly from an untreated control group on any of the measures. These findings, similar to those of Agras (1967), suggest that transfer to the feared situation is not gradual as proposed by Wolpe (1961) but has a rapid onset late in the therapeutic process. Thus, the present study was designed to assess for changes m snake phobic behavior throughout the course of systematic desensitization by testing for transfer at specified intervals of hierarchy completion.
METHOD Subjects
Approximately 40 female college undergraduates enrolled in introductory psychology classes reponded to a class announcement inviting female students who were afraid of snakes to volunteer for an experiment which might help eliminate their fears. Twenty-eight students satisfied the pretreatment Behavior Avoidance Test (BAT) criterion described below. From this pool, 20 females were matched with respect to their pretreatment BAT scores and assigned at random to either a systematic desensitization group or a no-treatment control group. Midway through the experiment one control subject refused to continue and was replaced by another volunteer from the pool with the same pretreatment BAT score. * This paper is based on a Master’s thesis carried out by the first author under supervision second author. Requests for reprints should be sent to the second author.
279
of the
280 Measures
CASE HISTORIES AND SHORTER COM~tUNICATlONS and pretreatment
criterion
The BAT consisting of 20 discrete, hierarchically arranged snake avoidance steps was used for the selection of subjects, for obtaining the pretreatment measure of approach behavior, and for assessing approach behavior at four subsequent stages of the experiment. This device, similar to that used by Rimm and Mahoney (1969), also served as the basis for construction of the common hierarchy used in the desensitization treatment. Step 1 of the BAT required subjects to enter the testing room containing a caged nonpoisonous 4-ft King snake and walk to the IO-ft marker on the floor. The succeeding five steps required subjects to approach the cage in 2-ft increments. The terminal task (Step 20) required subjects to touch their cheek with the snake. The steps were listed on a wall poster in the testing room and, in addition, a tape recorder was used for presenting each step to the subjects. Before entering the testing room for the pretest, the study was explained to the subjects as important clinical research dealing with different therapeutic procedures for treating fears. Subjects were informed that the testing room contained a harmless caged snake and that the experimenter would be present at all times. In performing each step on the BAT, the subjects were instructed not to attempt any step which caused anxiety and that they would not be forced to do anything against their consent. Subjects who were able to reach step 10 (touching the snake for 10 set) were eliminated from the study as displaying insufficient fear for the purpose of the experiment. The BAT was used in a similar manner during the course of the experiment for testing all subjects at four stages corresponding to completion by subjects in the desensmzation group of 25, 50, 75 and 100 per cent of the desensitrzatron hierarchy. Procedure
All subjects were seen mdividually throughout the experiment. Each member of the desensitization group was given two taped 40-min sessions in the Jacobsonian progressrve relaxation technique together with a copy of the relaxation instructions for practice between sessions. During the first relaxation session, the tape included introductory comments concerning the rationale for relaxation training and systematic desensrtization therapy. After the two relaxation sessions, subjects in the desensittzation group received 3-5 sessions of systematic desensitization of about 40 min each until they completed the common hierarchy. Desens~ti~tion was standard and followed closely the procedural details described by Barlow et al. (1969). Relaxation and desensitization were given in a room other than the one used for testing. During the first therapy session, each subject in the desensitization group began with the hierarchy item corresponding to the highest step completed on the pretest BAT. Although the mitial hierarchy item varied from subject to subject, the remaining items of any given subject’s hierarchy were divided mto four equal parts corresponding to 25, 50, 75 and 100 per cent completion of the hierarchy. At the end of each stage of desensitization (i.e. 25, 50, 75 and 100 per cent hierarchy completion), subjects were taken to the testing room and their scores on the BAT recorded. Thus, all subjects in the desensitization group were tested four times on the BAT during the course of therapy in addltion to the pretest. Subjects in the no-treatment control group participated only in the BAT assessment procedure. In addition to the pretest, these subjects were also tested four times during the experiment at approximately the same intervals as subjects in the desensitization group.
RESULTS The mean BAT pretest scores of the desensitization and control groups were 7.8 and 7.1, respectivelya level on the BAT between “touching the side of the cage with both hands” and “opening the cage and looking at the snake”. A t-test indicated that the two groups did not differ in their pretreatment approach behavior to the snake, t (18)=1.16, p>O.20. By the end of the experiment, all subjects in the desensitization group completed the 20&m common hierarchy, all improved their scores on the BAT by at least four steps, and 80 per cent completed the terminal task on the BAT. In the control group, 70 per cent of the subjects showed at least a two-step improvement on the BAT and 20 per cent completed the terminal task. At each of the four hierarchy completion testing stages, the mean BAT scores of the desensrtization group were 12.0, 15.6, 16.9 and 18.3, respectively. Corresponding means for the control group were 8.8, 9.9, 10.4 and 12.4. Thus, both groups showed gradual improvement in the feared situation (approach behavior on the BAT) throughout the experiment although for the desensttization group increments in improvement beyond the 50 per cent hierarchy completion testing stage were less than those in the first two stages. It was also found that improvement in approach behavior on the BAT lagged behind successful desexls~ti~tion of the imagined scenes for four of the ten desensitization subjects altl~ough two of them were able to complete the terminal task by the end of the experiment. For the remaining six subjects in the desensitization group, there was at least perfect transfer from therapy to the feared situation and in most cases, subjects were able to perform steps on the BAT prior to desensitization of the corresponding imagined scenes.
An analysis of variance for repeated measures of the BAT scores, including pretest scores, indicated that the difference between groups was significant, F (1, X8)= 11.04, p 4 0.01; that there was a significant testing stages effect, F (4,72) ~44.08, p < 0.01; and that the Groups X Testing Stages interaction was also significant, F (4, 72)=6.86, p< 0,Ol. As early as the 25 per cent hierarchy completion testing stage, the desensitization group showed a significant improvement over its pretest level, t (9)=3.61, pcO.01, and was reliably different from the control group, t (18)=2.19, ~~0.05.
DISCUSSION The gradurd improvement in the feared situation during the course of desensitization is consistent with Wolpe’s (1961) clinical observations, but the e&y significant improvement appears contradictory to the findings of Agras (1967) and Lang et al. (1965), wherein desensitization was well advanced before therapeutic effects were evident. Severai methodo~og~~~ variations between studies may account, in part, for these differences, however. For example, Agras treated agoraphobic patients in a clinic& setting, and improvement outside of therapy was based upon patient self-reports rather than standardized behavioral observations m the presence of the therapist or some trained observer. Although Lang et al. used snakephobic subjects from a college population, as in the present experiment, their subjects may have been more fearful, as only 13 of 23 were able to complete at least 75 per cent of tho hierarchy during a fixed number of 11 desensitization sessions, compared to the present group which required an average of four sessions to complete the entire hierarchy. Possibly more important, however, was the fact that Lang et al. were concerned only with pre-post therapy comparisons, whereas in the present study, subjects were repeatedly exposed to the feared situation, and changes in approach behavior were recurrently assessed, during the course of desensitization. Such repeated exposure may have functioned as a form of in viva desensitization, thereby facilitating, and possibly even accelerating, transfer (cf. Garfield ef af., 1967). However, this explanation could hardly account for the significant improvement shown by the desensitization group as early as 25 per cent completion of the hierarchy. On the other hand, present results may not be as contradictory to those of Lang ef ai. (1965) as they initiafly appeared to be, particularly if individual differences in ability to progress through the hierarchy are taken into consideration” In discussing the Lang et rrf. study, Lang (1969) noted that the number of hierarchy items completed is a ““good measure of therapy process . . . and if not crucial to successful desensitization, highly related to it” (p, 177). Thus, the Lang et‘ al. subjects who completed less than 75 per cent of the hierarchy may have been unwilling and/or unable to vividly imagine the anxiety producing scenes during desensitization to the degree necessary to benefit from therapy. By contrast, subjects who completed at least 75 per cent of the hierarchy may have been better visualizers, less reluctant to imagine the scenes and, like subjects in the present experiment, may have shown early and gradual reduction of phobic behavior had they been tested at regular intervals during the course of desensitization. In conclusion, the results of the present study suggest that reduction in phobic behavior may occur gradually throughout the course of desensrtization and that significant behavioral change may occur much earlier in therapy than previousXy thought. The possibility of facihtating transfer and of increasmg the efhciency of systematic desensitization by exposing clients to the actual situation during the course of desensitization warrants the further attention of practitioners and researchers.
LELAND E. RHODES
Veierans Admhistration Hospitial Phoenix, Arizona, U.S.A.
REFERENCES AGRAS W. S. (1967) TransFer during systematic BARLOW D. H.. LEITENBERGH.. AGRAS W. S.
desensitization therapy. Behav. Res. & Therapv 5,193-199* and WINCZE J. P. (1969) The transfer _. aan in systematic _ desensitization: An analogne study. BeAav. Rex B Therapy 7, i91-i96, GAT~FZELD Z. H., Dmwm P. L., SINGER B. A. and MCBREARTYJ. F. (1967) Effect of in v&o training on experimenta desensitization of a phobia. PqdroL Rep. 20, 515419. Hnw J. D., BUTCRER R. H. G. and STEVENSONI. (1969 Systematic dese~sit~tion therapy: An analysis of resufts in twenty-seven patients. Er. 3. I+&&. 11% 295-307. LANG P. J. (1969) The mechanics of desensitization and the laboratory study of human fear. In Bekwior Therapy: Appraisal und Status (Edited by C. M. FRANKS), pp. l60-191. McGraw-Hi& New York.
282
CASE HISTORIESAND SHORTER COMMUNICATIONS
LANG P. J., LAZOVIKD. A. and REYNOLDSD. J. (1965) Desensitization,
suggestibility, and pseudotherapy.
J. abnorm. Psych. 70, 395-402.
MEYERV. and CRISP A. H. (1966) Some problems in behavior therapy. Br. J. Psychiat. 112,367-381. RACHMANS. (1966) Studies in desensitization-III: Speed of generalization. Behav. Res. & Therapy 4,7-15. RIMM D. C. and MAHONEYM. J. (1969) The application of reinforcement and participant modeling procedures in the treatment of snake-phobic behavior. Behav. Res. & Therapy 7, 369-376. WOLPE J. (1954) Reciprocal inhibition as the main basis of psychotherapeutic effects. Archs. Neural. Psychiat.
72, 205-226.
WOLPEJ. (1961) The systematic desensitization treatment of neuroses. J. nerv. ment. Dis. 132,189-203. WOLPE J. (1963) Quantitative relationships in the systematic desensitization of phobias. Am. J. Psychiat. 119,1062-1068. WOLPEJ. (1966) Personal communication cited in Ham et al. (1966) Br. J. Psychiut. 112, 295-307.
Req.
& Therapy,
1972,
Vol.
IO, pp. 279 to 282.
CASE HISTORIES
Pergamon
Press.
Printed
AND SHORTER
in England
COMMUNICATIONS
Recurring assessment of changes in phobic behavior during the course of systematic desensitization * (Received
13 January
1972)
IN REFERENCE to his therapeutic system of systematic desensitization, Wolpe (1963) found that “there is almost invariably a one-to-one relationship between what the patient can imagine without anxiety and what he can experience m reality without anxiety” (p. 1063). Further, most patients reported gradual improvement in real life to previously fearful situations (or objects) as the result of desensitization (Wolpe, 1961). Wolpe’s findings Imply that as the patient progresses m therapy, there should be corresponding gradual extratherapeutic change or transfer in terms of his ability to deal with the fearful situation. Elsewhere, however, Wolpe (1954, 1966) noted that extratherapeutlc change may lag behind the lessening of anxiety in therapy, suggesting occasional difficulty in transfer. The most common observations of transfer have been made only at the endof a course of desensitization. In some studies, immediate transfer from the imagined to the real situation has been reported (e.g. Rachman, 1966), while in others transfer lagged behind completed desensihzation (Hain ef al., 1966; Meyer and Crisp, 1966). In order to assess this process more directly, Agras (1967), in a clinical study of five agoraphobic patients, tested for transfer during the course of desensitization. Improvement in the feared situation(s) was measured by obtaining self-reports from patients at each desensitization session. One patient’s improvement With the remaining patients behavioral was gradual and closely paralleled progress in desensitization. changes outside of therapy lagged behind the reduction of imaginal anxiety during desensitization, and improvement occurred mainly during the last half of therapy. Thus, a certain degree of progress in desensitization appeared necessary before noticeable clinical change was reported. However, since Agras did not employ an objective behavioral measure, and since controls were lacking, further exploration of transfer during the course of desensitization is needed. Although Lang, Lazovik and Reynolds (1965) did not test for transfer during desensitization, their data also suggested that therapy must be well advanced before effects are clearly evident. Their conclusion was based upon the high positive relationship found between the number of hierarchy items completed during desensitization and various pre-post therapy measures of fear change in an analogue study of snake phobic college students. Of the subjects treated by desensitization, those who completed at least 75 per cent of the hierarchy were found to show significantly greater pre-post improvement on all measures of anxiety and on the behavioral avoidance test than those who completed less than 75 per cent. Further, the less than 75 per cent group did not differ significantly from an untreated control group on any of the measures. These findings, similar to those of Agras (1967), suggest that transfer to the feared situation is not gradual as proposed by Wolpe (1961) but has a rapid onset late in the therapeutic process. Thus, the present study was designed to assess for changes m snake phobic behavior throughout the course of systematic desensitization by testing for transfer at specified intervals of hierarchy completion.
METHOD Subjects
Approximately 40 female college undergraduates enrolled in introductory psychology classes reponded to a class announcement inviting female students who were afraid of snakes to volunteer for an experiment which might help eliminate their fears. Twenty-eight students satisfied the pretreatment Behavior Avoidance Test (BAT) criterion described below. From this pool, 20 females were matched with respect to their pretreatment BAT scores and assigned at random to either a systematic desensitization group or a no-treatment control group. Midway through the experiment one control subject refused to continue and was replaced by another volunteer from the pool with the same pretreatment BAT score. * This paper is based on a Master’s thesis carried out by the first author under supervision second author. Requests for reprints should be sent to the second author.
279
of the
280 Measures
CASE HISTORIES AND SHORTER COM~tUNICATlONS and pretreatment
criterion
The BAT consisting of 20 discrete, hierarchically arranged snake avoidance steps was used for the selection of subjects, for obtaining the pretreatment measure of approach behavior, and for assessing approach behavior at four subsequent stages of the experiment. This device, similar to that used by Rimm and Mahoney (1969), also served as the basis for construction of the common hierarchy used in the desensitization treatment. Step 1 of the BAT required subjects to enter the testing room containing a caged nonpoisonous 4-ft King snake and walk to the IO-ft marker on the floor. The succeeding five steps required subjects to approach the cage in 2-ft increments. The terminal task (Step 20) required subjects to touch their cheek with the snake. The steps were listed on a wall poster in the testing room and, in addition, a tape recorder was used for presenting each step to the subjects. Before entering the testing room for the pretest, the study was explained to the subjects as important clinical research dealing with different therapeutic procedures for treating fears. Subjects were informed that the testing room contained a harmless caged snake and that the experimenter would be present at all times. In performing each step on the BAT, the subjects were instructed not to attempt any step which caused anxiety and that they would not be forced to do anything against their consent. Subjects who were able to reach step 10 (touching the snake for 10 set) were eliminated from the study as displaying insufficient fear for the purpose of the experiment. The BAT was used in a similar manner during the course of the experiment for testing all subjects at four stages corresponding to completion by subjects in the desensmzation group of 25, 50, 75 and 100 per cent of the desensitrzatron hierarchy. Procedure
All subjects were seen mdividually throughout the experiment. Each member of the desensitization group was given two taped 40-min sessions in the Jacobsonian progressrve relaxation technique together with a copy of the relaxation instructions for practice between sessions. During the first relaxation session, the tape included introductory comments concerning the rationale for relaxation training and systematic desensrtization therapy. After the two relaxation sessions, subjects in the desensittzation group received 3-5 sessions of systematic desensitization of about 40 min each until they completed the common hierarchy. Desens~ti~tion was standard and followed closely the procedural details described by Barlow et al. (1969). Relaxation and desensitization were given in a room other than the one used for testing. During the first therapy session, each subject in the desensitization group began with the hierarchy item corresponding to the highest step completed on the pretest BAT. Although the mitial hierarchy item varied from subject to subject, the remaining items of any given subject’s hierarchy were divided mto four equal parts corresponding to 25, 50, 75 and 100 per cent completion of the hierarchy. At the end of each stage of desensitization (i.e. 25, 50, 75 and 100 per cent hierarchy completion), subjects were taken to the testing room and their scores on the BAT recorded. Thus, all subjects in the desensitization group were tested four times on the BAT during the course of therapy in addltion to the pretest. Subjects in the no-treatment control group participated only in the BAT assessment procedure. In addition to the pretest, these subjects were also tested four times during the experiment at approximately the same intervals as subjects in the desensitization group.
RESULTS The mean BAT pretest scores of the desensitization and control groups were 7.8 and 7.1, respectivelya level on the BAT between “touching the side of the cage with both hands” and “opening the cage and looking at the snake”. A t-test indicated that the two groups did not differ in their pretreatment approach behavior to the snake, t (18)=1.16, p>O.20. By the end of the experiment, all subjects in the desensitization group completed the 20&m common hierarchy, all improved their scores on the BAT by at least four steps, and 80 per cent completed the terminal task on the BAT. In the control group, 70 per cent of the subjects showed at least a two-step improvement on the BAT and 20 per cent completed the terminal task. At each of the four hierarchy completion testing stages, the mean BAT scores of the desensrtization group were 12.0, 15.6, 16.9 and 18.3, respectively. Corresponding means for the control group were 8.8, 9.9, 10.4 and 12.4. Thus, both groups showed gradual improvement in the feared situation (approach behavior on the BAT) throughout the experiment although for the desensttization group increments in improvement beyond the 50 per cent hierarchy completion testing stage were less than those in the first two stages. It was also found that improvement in approach behavior on the BAT lagged behind successful desexls~ti~tion of the imagined scenes for four of the ten desensitization subjects altl~ough two of them were able to complete the terminal task by the end of the experiment. For the remaining six subjects in the desensitization group, there was at least perfect transfer from therapy to the feared situation and in most cases, subjects were able to perform steps on the BAT prior to desensitization of the corresponding imagined scenes.
An analysis of variance for repeated measures of the BAT scores, including pretest scores, indicated that the difference between groups was significant, F (1, X8)= 11.04, p 4 0.01; that there was a significant testing stages effect, F (4,72) ~44.08, p < 0.01; and that the Groups X Testing Stages interaction was also significant, F (4, 72)=6.86, p< 0,Ol. As early as the 25 per cent hierarchy completion testing stage, the desensitization group showed a significant improvement over its pretest level, t (9)=3.61, pcO.01, and was reliably different from the control group, t (18)=2.19, ~~0.05.
DISCUSSION The gradurd improvement in the feared situation during the course of desensitization is consistent with Wolpe’s (1961) clinical observations, but the e&y significant improvement appears contradictory to the findings of Agras (1967) and Lang et al. (1965), wherein desensitization was well advanced before therapeutic effects were evident. Severai methodo~og~~~ variations between studies may account, in part, for these differences, however. For example, Agras treated agoraphobic patients in a clinic& setting, and improvement outside of therapy was based upon patient self-reports rather than standardized behavioral observations m the presence of the therapist or some trained observer. Although Lang et al. used snakephobic subjects from a college population, as in the present experiment, their subjects may have been more fearful, as only 13 of 23 were able to complete at least 75 per cent of tho hierarchy during a fixed number of 11 desensitization sessions, compared to the present group which required an average of four sessions to complete the entire hierarchy. Possibly more important, however, was the fact that Lang et al. were concerned only with pre-post therapy comparisons, whereas in the present study, subjects were repeatedly exposed to the feared situation, and changes in approach behavior were recurrently assessed, during the course of desensitization. Such repeated exposure may have functioned as a form of in viva desensitization, thereby facilitating, and possibly even accelerating, transfer (cf. Garfield ef af., 1967). However, this explanation could hardly account for the significant improvement shown by the desensitization group as early as 25 per cent completion of the hierarchy. On the other hand, present results may not be as contradictory to those of Lang ef ai. (1965) as they initiafly appeared to be, particularly if individual differences in ability to progress through the hierarchy are taken into consideration” In discussing the Lang et rrf. study, Lang (1969) noted that the number of hierarchy items completed is a ““good measure of therapy process . . . and if not crucial to successful desensitization, highly related to it” (p, 177). Thus, the Lang et‘ al. subjects who completed less than 75 per cent of the hierarchy may have been unwilling and/or unable to vividly imagine the anxiety producing scenes during desensitization to the degree necessary to benefit from therapy. By contrast, subjects who completed at least 75 per cent of the hierarchy may have been better visualizers, less reluctant to imagine the scenes and, like subjects in the present experiment, may have shown early and gradual reduction of phobic behavior had they been tested at regular intervals during the course of desensitization. In conclusion, the results of the present study suggest that reduction in phobic behavior may occur gradually throughout the course of desensrtization and that significant behavioral change may occur much earlier in therapy than previousXy thought. The possibility of facihtating transfer and of increasmg the efhciency of systematic desensitization by exposing clients to the actual situation during the course of desensitization warrants the further attention of practitioners and researchers.
LELAND E. RHODES
Veierans Admhistration Hospitial Phoenix, Arizona, U.S.A.
REFERENCES AGRAS W. S. (1967) TransFer during systematic BARLOW D. H.. LEITENBERGH.. AGRAS W. S.
desensitization therapy. Behav. Res. & Therapv 5,193-199* and WINCZE J. P. (1969) The transfer _. aan in systematic _ desensitization: An analogne study. BeAav. Rex B Therapy 7, i91-i96, GAT~FZELD Z. H., Dmwm P. L., SINGER B. A. and MCBREARTYJ. F. (1967) Effect of in v&o training on experimenta desensitization of a phobia. PqdroL Rep. 20, 515419. Hnw J. D., BUTCRER R. H. G. and STEVENSONI. (1969 Systematic dese~sit~tion therapy: An analysis of resufts in twenty-seven patients. Er. 3. I+&&. 11% 295-307. LANG P. J. (1969) The mechanics of desensitization and the laboratory study of human fear. In Bekwior Therapy: Appraisal und Status (Edited by C. M. FRANKS), pp. l60-191. McGraw-Hi& New York.
282
CASE HISTORIESAND SHORTER COMMUNICATIONS
LANG P. J., LAZOVIKD. A. and REYNOLDSD. J. (1965) Desensitization,
suggestibility, and pseudotherapy.
J. abnorm. Psych. 70, 395-402.
MEYERV. and CRISP A. H. (1966) Some problems in behavior therapy. Br. J. Psychiat. 112,367-381. RACHMANS. (1966) Studies in desensitization-III: Speed of generalization. Behav. Res. & Therapy 4,7-15. RIMM D. C. and MAHONEYM. J. (1969) The application of reinforcement and participant modeling procedures in the treatment of snake-phobic behavior. Behav. Res. & Therapy 7, 369-376. WOLPE J. (1954) Reciprocal inhibition as the main basis of psychotherapeutic effects. Archs. Neural. Psychiat.
72, 205-226.
WOLPEJ. (1961) The systematic desensitization treatment of neuroses. J. nerv. ment. Dis. 132,189-203. WOLPE J. (1963) Quantitative relationships in the systematic desensitization of phobias. Am. J. Psychiat. 119,1062-1068. WOLPEJ. (1966) Personal communication cited in Ham et al. (1966) Br. J. Psychiut. 112, 295-307.