INDIVIDUAL DIFFERENCES IN SELF-REINFORCEMENT STYLE AND PERFORMANCE IN SELFAND THERAPIST-CONTROLLED WEIGHT REDUCTION PROGRAMS* RONALDH. ROZENSKY~and ALAN S. BELLACKS Clinical
Psychology
Centre.
Department of Psychology. University Pittsburgh, PA 15260, U.S.A. (Receiced
of Ptttsburgh,
4015 O’Hara
Street.
19 Ma!, 1975)
Summar?-Thirty-seven overweight subjects were recruited from the staff of a V. A. Hospital for a wetght reduction program. A self-reinforcement (SRI test was administered prior to treatment and subjects were classified as high or low self-reinforcers. Subjects were then exposed to one of two behavioral weight-reduction programs or a minimal treatment control condition. One treatment program emphasized self-control (SC) and the other incorporated a therapist controlled financial contingency for weight loss (EC). A significant interaction was found between SR group and treatment condition. High SR subjects lost weight at the rate of 1.49 pounds per week in the SC condition and only 0.37 pounds per week in EC. Low SR subjects lost at the rate of 1.06 and 1.01 pounds per week respectively in SC and EC. Implications for treatment and future research were discussed. The financial contingency had either neutral or negative effects. Caution was advised for any future use of that procedure.
Behavioral treatment procedures for weight-reduction and control have been found to be highly effective (Abramson, 1973; Bellack, 1975, a; Hall and Hall. 1974). Despite the overall success achieved by these methods, the results have been marked by a high degree of intra-group variability. Few studies have been able to demonstrate consistent and high levels of weight loss for any specific treatment techniques. One factor that undoubtedly contributes to the variability of results is the research strategy that has been adopted to examine treatment techniques. Almost invariably, treatment has been applied in a standardized manner to groups of subjects recruited and assigned to groups either on a random basis or according to weight. There has been no attempt to match subjects to treatments or to design treatments specifically for individual subjects. This approach is understandable given the exploratory nature of much of the existing research. However, the behavioral approach for weight reduction has now been sufficiently validated that a more individualized approach is appropriate. Abramson (1973), Bellack (1975, a) and Hall and Hall (1974) have all recommended that efforts be directed to the identification of individual predictor variables that would facilitate more effective subject-treatment pairing. There have been numerous attempts to isolate predictive factors. However, efforts in this regard have been restricted to correlational analyses of weight change and critereon scores across treatment conditions. Numerous variables including age, sex, history of weight problem and dieting success, marital status. motivation. anxiety, depression, and locus of control have all been examined in this manner. While there is some suggestion that younger subjects lose weight more readily than older subjects (Hall and Hall, 1974) and that subjects with an internal locus of control lose more readily than externals (Balch and Ross, 1975; Manno and Marston. 1972) the results of these analyses have been nonsignificant. In retrospect, these negative results are not surprising. The strategy * This article is based on a dissertation submitted in partial fulfillment of the requirements for the Ph.D. at the University of Pittsburgh. It was conducted by the first author under the direction of the second author. Portions of this paper were presented at the meeting of the European Association for Behavior Therapy. London 1974. Preparation of this manuscript was supported, in part. by Grant MH 26176-01 from NIMH to the second author. t Author to whom requests for reprints should be addressed. $ Now at Downie V. A. Hospital, Downie, Illinois. 357
3%
RONALD H. ROZENSII
and
ALAY
S.
BELu(.h
of conducting post hoc correlational analyses with the results of both effective and ineffective treatment procedures combined is not likely to yield highly meaningful information. Even statistically significant correlations obtained under such circumstances are likely to account for only a small portion of the relevant variance. Kiesler (1966) has suggested what promises to be a more effective approach. First. the characteristics or skills necessary for the utilization of a specific treatment procedure should be identified. Second. individuals independently assessed as differing on those characteristics should be selected. and finally. the performance of the disparate groups on the target program should be compared. This strategy would allow for the identification of an! Treatment x Subject interactions, as well as overall treatment and subject differences. One aspect of behavior that Laries across individuals and has been employed in a number of treatment programs is self-control (SC). There ha1.e been numerous demonstrations of the general effectiveness of SC programs for weight reduction (Bellack. in press: Bellack. Rozensky and Schwartz. 1974: Hagen. 1974: Mahoney. 1974). Subjects in these programs have been expected to modify their own behavior with the use of a number of self-administered techniques including self-monitoring (SM). self-reinforcement (SR). and stimulus control. Therapist involvement has been limited to providing information and low levels of social reinforcement. While the specific procedures employed have varied across studies. the predominant emphasis has been the subject as his own change agent. These programs have been administered with the tacit, but unverified. assumption that all sub_jects are equally adept at or amenable to following SC procedures. The general assumption that patients come to treatment with similar skills or stylistic patterns has been questioned by Kiesler (1966). He coined the term ‘Patient Uniformity Myth’ to describe this belief. In conducting research on SC-based weight reduction programs. one is struck by the fact that while those subjects who administer the procedures as instructed generally do lose weight. some subjects simply do not emplo) the SC procedures regularly or contingently. One possible explanation for this phenomenon is that there are individual differences in ability and/or inclination to effectivel), utilize SC techniques. This contention is supported by a number of analogue and clinical investigations of the SC process. Bellack (Bellack, 1975, b; Bellack and Tillman. 1974) has shown that there are individual differences in self-evaluative style and the tendency to administer SR. Kanfer. Duerfeldt and Le Page (1969). and Marston (1964) have demonstrated that there are individual differences in the use of SR which are consistent across situations. SC behavior is generally presumed to be learned. The existence of these differences is apparent]\a result of the idiosyncratic nature of learning histories of SC behavior (Bandura and Kupers. 1964: Drabman. Spitalnik and O’Leary. 1973: Karoly and Kanfer. 1974: Kazdin. 1974). Two studies have been conducted which directly suggest that SC differences afiect behavior change. Rozensky and Bellack (1974) conducted a retrospective study in which they found that individuals able to lose weight or quit smoking cigarettes administered significantly more SR for performance on a simple verbal learning task than individuals who had been unable to lose weight or quit smoking. Bellack, Glanz and Simon (in press) secured samples of SR behavior from volunteers for a weight reduction program. SR consisted of lcttcr grades for performance on a time estimation task. Subjects identified as high self-reinforcers lost significantly more weight in a SC program than low sclf-rcinforcers and maintained their losses better after treatment ended. The purpose of the present study was to examine the relationship between SK style and performance in treatment. It was presumed that maximum treatment effectiveness would result from compatible treatment-subject pairings. A factorial rcscarch design was therefore employed. Sub.jects were first classified as high or low on the tendency to administer SR. They were then assigned to a weight reduction program that emphasized either SC or external (therapist) control. The SC program was similar to that developed b>, Bellack (Bellack. Rozensky and Schwartz, 1974; Bellack. Schwartz and Rozenskq. 1973). The program supplements a standard behavioral (stimulus control)
Individual
differences
in self-reinforcement
style
359
with pre-eating self-monitoring of all eating behavior. This SM procedure is designed to facilitate self-evaluation (SE) and SR of behavior by increasing subjects awareness of their intended behavior. Those individuals who can use SE and SR effectively should, therefore, do better than those who cannot or do not use them effectively. The external control (EC) program involved therapist administered financial contingencies for weight loss. It was expected that this aspect would meet the needs of low self-controllers better than the SC program. Positive results for similar EC programs have been reported by Jeffrey (1974). Hall (1972). and Harris and Bruner (1971). In contrast, Abrahms and Allen (1974) and Harris and Hallbauer (1971) did not find financial contingency procedures to be effective. A secondary purpose of the present study was. therefore. to examine the efficacy of this approach both across subjects and within subject types (e.g., high and low SC).
p&age
METHOD Subjects were volunteers recruited from the staff of a large Veterans Administration Hospital (General Medical Surgical). All subjects expressed the desire to lose at least 15 pounds. were not involved in any other programs or treatments for weight loss and had no history of hormonal or metabolic dysfunction. Each subject was required to deposit $16 with the experimenter, to guarantee their participation throughout the program. The average weight at the beginning of treatment was 171.24 pounds and the mean age was 35.71 years. Prior to being assigned to a treatment group, each subject was seen individually for assessment of SR behavior. The SR testing procedure was similar to that employed by Bellack and Tillman (1974), and Rozensky and Bellack (1974). The subject was seated at a table facing a blank wall which served as a screen for projection of 35 mm slides. After the procedure was explained, 30 three letter words were flashed on the wall sequentially at a rate of one per second. Following a 2 min rest period 50 slides. each containing three words. were presented sequentially; exposure time for each three word stimulus was 5 sec. One of the words on ei:ch slide stimulus had appeared on the original list. The subject was required to identify the word he believed to be correct and then subjectively evaluate his guess. If he was confident that he was correct, he was to administer a SR. SR was operationally defined as a positive self-evaluation paired with the overt response of pressing a telegraph key, which lighted a small red lamp for 1.5 sec. Subjects were divided into high and low SR groups by performing a median split of SR scores (number of SRs administered). The median was 21. High self-reinforcers administered an average of 25.41 SRs and Lows administered an average of 15.32. This difference was highly significant (p < 0.001). As in previous research. there was no difference between the groups in number of correct responses on the memory task or in accuracy of SR administration. Subjects in each SR group were randomly assigned to one of the three treatment conditions: Self-control, External control, or Minimal Contact. All subjects were presented with the same basic weight reduction program. The program consists of three components: establishment of a negative energy balance, stimulus control, and self-monitoring (SM). The program is designed to generate moderate weight losses (l-2 pounds per week). and modify eating habits through the application of SC techniques. The SM procedure was pre-eating monitoring: subjects were instructed to make a written record of intended food intake immediately prior to eating. This procedure has been shown to be an effective adjunct to a basic weight reduction program (Bellack, Rozensky and Schwartz, 1974: Bellack, Schwartz and Rozensky, 1974). The entire program was described in a treatment manual, which was presented to all subjects at initial orientation meetings. These meetings were conducted separately with each group. SC Cor~ditiori (SC). In addition to following the procedures in the treatment manual, subjects in this condition were required to mail their monitoring records to the therapist every morning. Each week the therapist mailed them a set of preaddressed envelopes,
360
RONALV H. ROZENSKT and
ALAN S. BELLAC‘K
some general diet information. and comments about their records from the preceeding week. The only direct contact with the therapist took place at the initial meeting. and at weighins conducted 7 and 14 weeks later. Mail contact was maintained for 7 weeks, and there was a 7 week follow-up. Seven High .SR and seven Low SR subjects were assigned to this condition; one Low subject dropped out. EC ~~~z~~jfj~~~ (EC). Subjects in this condition were also instructed to follow the manual and mail their SM records to the therapist daily. In addition. they were placed on a financial contingency. They reported for weekly weight checks. at which time portions of their deposits were returned or forfeited contingent on weight loss. Two dollars of the deposit was available for reinforcement each week and was returned at the rate of $1.00 per pound lost. Any money not awarded (i.e.. subject lost less than 3 pounds) was forfeited and was apportioned among those subjects who did lose weight that week. Interpersona contact at the weigh-ins was held to a minimum. Subjects were, however. provided with equivalent information to that mailed to SC subjects. The contingency was in effect for 7 weeks, and there was a 7 week follow-up. Eight High SR subjects (one of whom dropped out) and seven Low SR subjects were assigned to this condition. Mininml cmract comfirim (MC). This condition was included as a control for participation in a diet program. The subjects were given all the information necessary to change their behavior. but they had no ongoing contact with the therapist. They were seen for the orientation meeting and for weight checks 7 and I4 weeks later. Based on the results of previous research. it was expected that subjects in this condition would not lose meaningful amounts of weight. Six High SR and five Low SR subjects were assigned to this condition, and one High subject dropped out. The second author served as therapist for all groups. Given the low level of contact involved in al1 conditions. the possibility of significant bias effects was presumed to be minimal. RESULTS The final sample included 32 women and 5 men. All groups contained one male subject with the exception of Low SR-EC. One way analyses of variance (or Chi Squares for dichotomous variables) conducted on pre-treatment data indicated that there were no initial differences between groups in weight, age. marital status, self-reported motivation to lose weight (scored on a t-10 scale), number of years overweight or dieting experience. The research literature on weight reduction has been marked by considerable controversy over the choice of dependent variables. While the most frequentIy reported variable has been change in percentage overweight. Bellack and Rozensky (1975) have pointed to a number of difficulties with that measure. They recommended that statistical analyses be conducted on both raw weight change and on (arc sin) proportion of body weight lost. That strategy was followed in the present study. It was expected that the two MC groups would not differ from one another. The results for those groups at the end of treatment and at follow-up were compared (on both measures) with t-tests. None of the differences were sign~~cant. and the two groups were combined for subsequent analyses. All major analyses. therefore. were conducted as 2 x 2 factorial analyses of variance with a single control group (Winer, 1962; p. 469). The results are summarized in Table 1. Subjects in the SC condition lost significantly more weight during treatment than subjects in the EC condition (F (1.32) = 24.10, p < 0.001). SC subjects lost weight at a rate of 1.28 pounds per week, which was within the goals of the program. This rate of loss compares favorably to the results of other programs. involving greater amount of therapist contact (Hall and Hall, 1974). A more complete picture of the results is provided by the analyses on arc sin proportion weight loss. The results for both treatment conditions combined were significantly different from the control conditon (F( 1,32) = 4.41, p < 0.05). This difference was primarily a function of the performance of subjects in the SC condition. SC’ subjects lost a greater
Individual Table
differences
1. Weight
changes
in self-reinforcement across
treatment
style
361
and follow-up
Group Period Measure Pre- to post-treatment Loss in pounds Percentage body wt lost Pre-treatment to follow-up Loss in pounds Percentage body wt lost
Low SR SC
High SR EC
Low SR EC
MC
10.70
1.45
2.60
1.07
4.85
5.81
4.12
1.68
4.35
2.91
9.25
7.04
1.81
5.35
3.87
3.52
3.11
1.83
2.47
1.95
High SR SC
proportion of body weight than both EC subjects (F(1,32) = 32.83, p < 0.001) and MC subjects (F(1,32) = 5.87, p < 0.05). The EC condition was no more effective than MC (F( 1,32) < 1). Conclusions about the difference between SC and EC must be qualified by the fact that the interaction between treatment and SR group was highly significant (F(l,32) = 11.83, p < 0.01). As shown in Table 1, Low SR subjects did moderately well in both SC and EC programs. However, the results for High SR subjects differed greatly in the two programs. High SR subjects lost an average of 5.81% body weight (10.70 pounds) in the SC condition while losing only 1.68% (2.60 pounds) in the EC condition. This pattern of results was maintained through the follow-up period. The analysis on raw weight change again indicated that the SC condition was more effective than the EC condition (F( 1,32) = 14.01, p < 0.001) over the entire 14-week period. The Treatment x SR interaction was also significant (F(1,32) = 5.08, p < 0.05). The arc sin proportion analyses indicated that SC subjects manifested a greater reduction in body weight than both EC subjects (F(1,32) = 5.41, p < 0.05) and MC subjects (F(1,32) = 5.31, p < 0.05). The EC condition did not differ from MC (F(1,32) < 1). The interaction effect for this analysis approached significance. Pearson Product Moment correlation coefficients were calculated between weight loss and a number of pre-treatment demographic variables and post-treatment questionnaire responses. None of the pre-treatment variables (including age and motivation) were significantly correlated with weight loss. The self-reported application of the following program recommendations was significantly correlated with weight loss: setting a goal (1.= 0.67) p < 0.001) avoiding snacks (r = 0.43, p < 0.05) taking one helping at a time (r = 0.41) p < 0.05), and engaging in alternative activity to avoid eating (r = 0.41, p < 0.05). There has been some conjecture about the advisability of frequent weight checks given the small daily weight changes that can be achieved. Interestingly, there were significant negative correlations between weight loss and frequency with which subjects reported weighing themselves during the treatment period (I = -0.42, p < 0.05) and follow-up period (r = -0.38, p < 0.05). DISCUSSION
The results provide strong support for the general hypothesis that subject characteristics interact with treatment parameters. The significant interaction indicated that the effectiveness of the treatment programs was quite different for the two SR groups, and conversely, that the probability of weight-loss was a function of the treatment to which the subject was exposed. While this general finding was expected, the nature of the interaction was somewhat surprising. High SR subjects lost a substantial amount of weight in the SC program and an inconsequential amount of weight in the EC condition. In fact, High SR subjects in EC lost less than subjects in the control group. Given that EC consisted of SC combined with a financial contingency, it would appear that the contingency decreased the effectiveness of an otherwise effective program. There are several possible explanations of this finding. The FC procedure was imposed upon
subjects by the therapist as a presumably necessary condition for weight loss. Davison (19731 has suggested that behavior modification programs are susceptible to ‘counter control’ by patients: resistance to manipulation by the therapist despite the desire to change. If High SR subjects prefer. and characteristically emphasize self-control over their behavior, it is possible that they responded negatively to the emphasis on external control, to the particular. EC procedure employed. or to the fact that such control was imposed upon them. If they experienced any of these reactions. they might have engaged in ‘counter control’ as a response to being maIlipulated. This hyrpothesis presumes that subjects actively (albeit covertly) resisted the program. A more parsimonious explanation is that while there may have been a negative reaction to the EC procedure. the effects were indirect. Because of its high (negative) valance. the FC procedure generated a disproportionate amount of attention and distracted subjects from other. more effective components of the program (e.g., stimulus control precedures. SM). Some indirect support for this hypothesis is provided by Behack, Rozensky and Schwartz (1974). In a slightly different context. they also found that the addition of an ineffective program element could mitigate the effects of a viable treatment procedure. While further research is necessary to verify this finding, greater caution is advised in the construction of multi-component treatment packages. When presented with a smorgasboard of techniques, subjects are at least as likely to focus on ineffective as effective elements. The results of such a focus. as in this study. can be contratherapeutic. The Low SR subjects did moderately well in both treatment conditions. The FC procedure did not result in greater weight losses than the basic SC program. Conversely, FC did not reduce the effectiveness of the SC components. This is consistent with the hypothesis presented above for the High SR group. Low SR subjects would not be expected to respond affectively (either positively or negatively) to EC. The FC procedure would not. therefore. have a disproportionate impact on their response to the program. The overall differences in weight loss between High and Low SR subjects was not significant. primarily as a function of the significant interaction between SR group and treatment condition. It should be emphasized here that from the perspective of both individual differences in preference or ability and program demands, SC and EC exist along continua (Thoresen and Mahoney. 1974). Low SR subjects were not incapable of using SC, but were low relative to the specific group of Highs selected. Both treatment programs involved the application of both SC and EC; the EC program emphasized EC more than the SC program did. High SK subjects in the SC condition lost an average of 3.25 pounds ( I .69”,, body wt.) more than Low SR subjects in that condition. That difference amounts to almost one half pound per week, and is quite impressive given that subjects were classified simply on the basis of a median split of SR scores. It seems likely that an even greater difference would have been found if more disparate groups (e.g.. upper and lower thirds of the distribution) had been selected. These positive findings indicate that additional clinical and analogue research on SR differentiation is warranted. Clinical research should include applications with other populations as well as refinement of the assessment device. There are several questions that have been raised by these results aside from potential clinical utility. The first issue pertains to the specific parameters of the operationally defined SR responses secured on the memory task in this study, or the (time estimation) task used by Bellack ef al. (in press). These responses could represent the tendency to administer SR, stringency of standards for administration of SR. etc. There is also some suggestion that responses of this type are self-evaluations. rather than reinforcements (Bandura, 1971). A related issue is the specific nature of the relationship between responses on these tasks and performance in SC programs. Both SE and SR are fundamental components of SC behavior (Kanfer and Karoly, 1972). Deficits in either component could result in performance decrements in SC programs. In that regard it was reported above that several investigators have found a relationship between locus of control and weight loss. Bellack (Bellack. 1975, h: Bellack and Tilfman, 1974) has found that externals
Individual differences
in self-reinforcement
style
363
(who lose less weight) are more dependent upon others for evaluation of their behavior and make less effective use of self-reinforcement than internals. He concluded that the IE scale is measuring an aspect of self-control behavior. The relationship of locus of control and weight can thus be viewed as support for the conclusions drawn from the present study: response to treatment is affected by pre-existing differences in SC behavior. The SC program was effective for both High and Low SR subjects. These results provided confirmation of previous findings that the pre-behavior monitoring technique can be a powerful adjunct to a basic stimulus control program. The applicability of this procedure for other clinical populations should be explored. The difference in performance between the SC and MC groups suggests that some minimal degree of external control is necessary, even for High SR individuals. That control could serve as a discriminative stimulus for SC and/or as a reinforcer prr se. The future use of FC procedures similar to the one employed in this study is contraindicated. Considerable effort is necessary for application of the technique and the effectiveness is questionable. In the present study, FC had either neutral or negative effects. Jeffrey (1974) did report positive results for FC during treatment, but the effects dissipated by the time of a follow-up. There are instances when some form of externally managed contingencies would be applicable (e.g.. a patient with gross SC deficits). Two modifications of the FC procedure employed here should be considered for those situations. First, an effort should be made to insure that the size of the monetary reinforcer is adequate. Second, reinforcements (or some representative such as points or tokens) should be administered on a considerably more immediate basis than once each week.
REFERENCES ABRAHMSJ. and ALLEN G. (1974) Comparative effectiveness of situational programming, financial pay-offs and group pressure in weight reduction. Behar. Therupy 5, 391-400. ABRAM~~NE. E. (1973) A review of behavioral approaches to weight control. Behar. Res. and Therapy 11, 547-546.
BALCHP. and Ross A. W. (1975) Predicting success in weight reduction as a function of locus of control: a unidemensional and multidemensional approach. J. consulr and c/k. Psycho/. 43, 119. BANDURAA. (1971) Self-reinforcement processes. In: The Narure of Reinforcement. (Ed. R. GLASER)Academic Press. New York.
BANDURAA. and KUPERSC. J. (1964) Transmission of patterns of self-reinforcement through modeling. J. ahnorm. sot. Psyehol. 69, 1-9. BELLA~KA. S. (1975a) Behavior therapy for weight reduction: an evaluative review. Ad&r. Behac. 1, 73-82. BELLACXA. S. Self-monitoring and self-reinforcement in weight reduction. Behar. Therapy, in press. BELLACKA. S. (1975b) Self-evaluation. self-reinforcement and locus of control. J. res. Person. 9. 158-167. BELLACKA. S.. GLANZ L. and SIMON R. Positive and negative covert reinforcement in the treatment of obesity. J. cnnsulr. clin. Ps~eho~., in press. BELLACKA. S. and R~ZENXY R. H. (1975) The selection of dependent variabies for weight reduction studies. J. Be/xx.
Tkercrpy crnd exp. Ps~chiaf. 6, 83-84.
BELLACKA. S., ROZENSKYR. H. and SCHWARTZJ. (1974) A comparison of two forms of self-monitoring in a behavioral weight reduction program. Behur. Therccpy 5, 523-530. BELLACKA. S., SCHWARTZJ. and ROZENS~YR. H. (1974) The contribution of external control to self-control in a weight reduction program. J. Behur. Ther. und esp. fs~,cb~~zi.5, 245250. BELLACKA. S. and TILLMANW. (1974) The effects of task and experimenter feedback on the self-reinforcement behavior of internals and externals. J. cnnstrlr and c/in. Psycho/. 42, 330-336. DAVISONG. C. (1973) Counter
Psychology
Centre.
Department of Psychology. University Pittsburgh, PA 15260, U.S.A. (Receiced
of Ptttsburgh,
4015 O’Hara
Street.
19 Ma!, 1975)
Summar?-Thirty-seven overweight subjects were recruited from the staff of a V. A. Hospital for a wetght reduction program. A self-reinforcement (SRI test was administered prior to treatment and subjects were classified as high or low self-reinforcers. Subjects were then exposed to one of two behavioral weight-reduction programs or a minimal treatment control condition. One treatment program emphasized self-control (SC) and the other incorporated a therapist controlled financial contingency for weight loss (EC). A significant interaction was found between SR group and treatment condition. High SR subjects lost weight at the rate of 1.49 pounds per week in the SC condition and only 0.37 pounds per week in EC. Low SR subjects lost at the rate of 1.06 and 1.01 pounds per week respectively in SC and EC. Implications for treatment and future research were discussed. The financial contingency had either neutral or negative effects. Caution was advised for any future use of that procedure.
Behavioral treatment procedures for weight-reduction and control have been found to be highly effective (Abramson, 1973; Bellack, 1975, a; Hall and Hall. 1974). Despite the overall success achieved by these methods, the results have been marked by a high degree of intra-group variability. Few studies have been able to demonstrate consistent and high levels of weight loss for any specific treatment techniques. One factor that undoubtedly contributes to the variability of results is the research strategy that has been adopted to examine treatment techniques. Almost invariably, treatment has been applied in a standardized manner to groups of subjects recruited and assigned to groups either on a random basis or according to weight. There has been no attempt to match subjects to treatments or to design treatments specifically for individual subjects. This approach is understandable given the exploratory nature of much of the existing research. However, the behavioral approach for weight reduction has now been sufficiently validated that a more individualized approach is appropriate. Abramson (1973), Bellack (1975, a) and Hall and Hall (1974) have all recommended that efforts be directed to the identification of individual predictor variables that would facilitate more effective subject-treatment pairing. There have been numerous attempts to isolate predictive factors. However, efforts in this regard have been restricted to correlational analyses of weight change and critereon scores across treatment conditions. Numerous variables including age, sex, history of weight problem and dieting success, marital status. motivation. anxiety, depression, and locus of control have all been examined in this manner. While there is some suggestion that younger subjects lose weight more readily than older subjects (Hall and Hall, 1974) and that subjects with an internal locus of control lose more readily than externals (Balch and Ross, 1975; Manno and Marston. 1972) the results of these analyses have been nonsignificant. In retrospect, these negative results are not surprising. The strategy * This article is based on a dissertation submitted in partial fulfillment of the requirements for the Ph.D. at the University of Pittsburgh. It was conducted by the first author under the direction of the second author. Portions of this paper were presented at the meeting of the European Association for Behavior Therapy. London 1974. Preparation of this manuscript was supported, in part. by Grant MH 26176-01 from NIMH to the second author. t Author to whom requests for reprints should be addressed. $ Now at Downie V. A. Hospital, Downie, Illinois. 357
3%
RONALD H. ROZENSII
and
ALAY
S.
BELu(.h
of conducting post hoc correlational analyses with the results of both effective and ineffective treatment procedures combined is not likely to yield highly meaningful information. Even statistically significant correlations obtained under such circumstances are likely to account for only a small portion of the relevant variance. Kiesler (1966) has suggested what promises to be a more effective approach. First. the characteristics or skills necessary for the utilization of a specific treatment procedure should be identified. Second. individuals independently assessed as differing on those characteristics should be selected. and finally. the performance of the disparate groups on the target program should be compared. This strategy would allow for the identification of an! Treatment x Subject interactions, as well as overall treatment and subject differences. One aspect of behavior that Laries across individuals and has been employed in a number of treatment programs is self-control (SC). There ha1.e been numerous demonstrations of the general effectiveness of SC programs for weight reduction (Bellack. in press: Bellack. Rozensky and Schwartz. 1974: Hagen. 1974: Mahoney. 1974). Subjects in these programs have been expected to modify their own behavior with the use of a number of self-administered techniques including self-monitoring (SM). self-reinforcement (SR). and stimulus control. Therapist involvement has been limited to providing information and low levels of social reinforcement. While the specific procedures employed have varied across studies. the predominant emphasis has been the subject as his own change agent. These programs have been administered with the tacit, but unverified. assumption that all sub_jects are equally adept at or amenable to following SC procedures. The general assumption that patients come to treatment with similar skills or stylistic patterns has been questioned by Kiesler (1966). He coined the term ‘Patient Uniformity Myth’ to describe this belief. In conducting research on SC-based weight reduction programs. one is struck by the fact that while those subjects who administer the procedures as instructed generally do lose weight. some subjects simply do not emplo) the SC procedures regularly or contingently. One possible explanation for this phenomenon is that there are individual differences in ability and/or inclination to effectivel), utilize SC techniques. This contention is supported by a number of analogue and clinical investigations of the SC process. Bellack (Bellack, 1975, b; Bellack and Tillman. 1974) has shown that there are individual differences in self-evaluative style and the tendency to administer SR. Kanfer. Duerfeldt and Le Page (1969). and Marston (1964) have demonstrated that there are individual differences in the use of SR which are consistent across situations. SC behavior is generally presumed to be learned. The existence of these differences is apparent]\a result of the idiosyncratic nature of learning histories of SC behavior (Bandura and Kupers. 1964: Drabman. Spitalnik and O’Leary. 1973: Karoly and Kanfer. 1974: Kazdin. 1974). Two studies have been conducted which directly suggest that SC differences afiect behavior change. Rozensky and Bellack (1974) conducted a retrospective study in which they found that individuals able to lose weight or quit smoking cigarettes administered significantly more SR for performance on a simple verbal learning task than individuals who had been unable to lose weight or quit smoking. Bellack, Glanz and Simon (in press) secured samples of SR behavior from volunteers for a weight reduction program. SR consisted of lcttcr grades for performance on a time estimation task. Subjects identified as high self-reinforcers lost significantly more weight in a SC program than low sclf-rcinforcers and maintained their losses better after treatment ended. The purpose of the present study was to examine the relationship between SK style and performance in treatment. It was presumed that maximum treatment effectiveness would result from compatible treatment-subject pairings. A factorial rcscarch design was therefore employed. Sub.jects were first classified as high or low on the tendency to administer SR. They were then assigned to a weight reduction program that emphasized either SC or external (therapist) control. The SC program was similar to that developed b>, Bellack (Bellack. Rozensky and Schwartz, 1974; Bellack. Schwartz and Rozenskq. 1973). The program supplements a standard behavioral (stimulus control)
Individual
differences
in self-reinforcement
style
359
with pre-eating self-monitoring of all eating behavior. This SM procedure is designed to facilitate self-evaluation (SE) and SR of behavior by increasing subjects awareness of their intended behavior. Those individuals who can use SE and SR effectively should, therefore, do better than those who cannot or do not use them effectively. The external control (EC) program involved therapist administered financial contingencies for weight loss. It was expected that this aspect would meet the needs of low self-controllers better than the SC program. Positive results for similar EC programs have been reported by Jeffrey (1974). Hall (1972). and Harris and Bruner (1971). In contrast, Abrahms and Allen (1974) and Harris and Hallbauer (1971) did not find financial contingency procedures to be effective. A secondary purpose of the present study was. therefore. to examine the efficacy of this approach both across subjects and within subject types (e.g., high and low SC).
p&age
METHOD Subjects were volunteers recruited from the staff of a large Veterans Administration Hospital (General Medical Surgical). All subjects expressed the desire to lose at least 15 pounds. were not involved in any other programs or treatments for weight loss and had no history of hormonal or metabolic dysfunction. Each subject was required to deposit $16 with the experimenter, to guarantee their participation throughout the program. The average weight at the beginning of treatment was 171.24 pounds and the mean age was 35.71 years. Prior to being assigned to a treatment group, each subject was seen individually for assessment of SR behavior. The SR testing procedure was similar to that employed by Bellack and Tillman (1974), and Rozensky and Bellack (1974). The subject was seated at a table facing a blank wall which served as a screen for projection of 35 mm slides. After the procedure was explained, 30 three letter words were flashed on the wall sequentially at a rate of one per second. Following a 2 min rest period 50 slides. each containing three words. were presented sequentially; exposure time for each three word stimulus was 5 sec. One of the words on ei:ch slide stimulus had appeared on the original list. The subject was required to identify the word he believed to be correct and then subjectively evaluate his guess. If he was confident that he was correct, he was to administer a SR. SR was operationally defined as a positive self-evaluation paired with the overt response of pressing a telegraph key, which lighted a small red lamp for 1.5 sec. Subjects were divided into high and low SR groups by performing a median split of SR scores (number of SRs administered). The median was 21. High self-reinforcers administered an average of 25.41 SRs and Lows administered an average of 15.32. This difference was highly significant (p < 0.001). As in previous research. there was no difference between the groups in number of correct responses on the memory task or in accuracy of SR administration. Subjects in each SR group were randomly assigned to one of the three treatment conditions: Self-control, External control, or Minimal Contact. All subjects were presented with the same basic weight reduction program. The program consists of three components: establishment of a negative energy balance, stimulus control, and self-monitoring (SM). The program is designed to generate moderate weight losses (l-2 pounds per week). and modify eating habits through the application of SC techniques. The SM procedure was pre-eating monitoring: subjects were instructed to make a written record of intended food intake immediately prior to eating. This procedure has been shown to be an effective adjunct to a basic weight reduction program (Bellack, Rozensky and Schwartz, 1974: Bellack, Schwartz and Rozensky, 1974). The entire program was described in a treatment manual, which was presented to all subjects at initial orientation meetings. These meetings were conducted separately with each group. SC Cor~ditiori (SC). In addition to following the procedures in the treatment manual, subjects in this condition were required to mail their monitoring records to the therapist every morning. Each week the therapist mailed them a set of preaddressed envelopes,
360
RONALV H. ROZENSKT and
ALAN S. BELLAC‘K
some general diet information. and comments about their records from the preceeding week. The only direct contact with the therapist took place at the initial meeting. and at weighins conducted 7 and 14 weeks later. Mail contact was maintained for 7 weeks, and there was a 7 week follow-up. Seven High .SR and seven Low SR subjects were assigned to this condition; one Low subject dropped out. EC ~~~z~~jfj~~~ (EC). Subjects in this condition were also instructed to follow the manual and mail their SM records to the therapist daily. In addition. they were placed on a financial contingency. They reported for weekly weight checks. at which time portions of their deposits were returned or forfeited contingent on weight loss. Two dollars of the deposit was available for reinforcement each week and was returned at the rate of $1.00 per pound lost. Any money not awarded (i.e.. subject lost less than 3 pounds) was forfeited and was apportioned among those subjects who did lose weight that week. Interpersona contact at the weigh-ins was held to a minimum. Subjects were, however. provided with equivalent information to that mailed to SC subjects. The contingency was in effect for 7 weeks, and there was a 7 week follow-up. Eight High SR subjects (one of whom dropped out) and seven Low SR subjects were assigned to this condition. Mininml cmract comfirim (MC). This condition was included as a control for participation in a diet program. The subjects were given all the information necessary to change their behavior. but they had no ongoing contact with the therapist. They were seen for the orientation meeting and for weight checks 7 and I4 weeks later. Based on the results of previous research. it was expected that subjects in this condition would not lose meaningful amounts of weight. Six High SR and five Low SR subjects were assigned to this condition, and one High subject dropped out. The second author served as therapist for all groups. Given the low level of contact involved in al1 conditions. the possibility of significant bias effects was presumed to be minimal. RESULTS The final sample included 32 women and 5 men. All groups contained one male subject with the exception of Low SR-EC. One way analyses of variance (or Chi Squares for dichotomous variables) conducted on pre-treatment data indicated that there were no initial differences between groups in weight, age. marital status, self-reported motivation to lose weight (scored on a t-10 scale), number of years overweight or dieting experience. The research literature on weight reduction has been marked by considerable controversy over the choice of dependent variables. While the most frequentIy reported variable has been change in percentage overweight. Bellack and Rozensky (1975) have pointed to a number of difficulties with that measure. They recommended that statistical analyses be conducted on both raw weight change and on (arc sin) proportion of body weight lost. That strategy was followed in the present study. It was expected that the two MC groups would not differ from one another. The results for those groups at the end of treatment and at follow-up were compared (on both measures) with t-tests. None of the differences were sign~~cant. and the two groups were combined for subsequent analyses. All major analyses. therefore. were conducted as 2 x 2 factorial analyses of variance with a single control group (Winer, 1962; p. 469). The results are summarized in Table 1. Subjects in the SC condition lost significantly more weight during treatment than subjects in the EC condition (F (1.32) = 24.10, p < 0.001). SC subjects lost weight at a rate of 1.28 pounds per week, which was within the goals of the program. This rate of loss compares favorably to the results of other programs. involving greater amount of therapist contact (Hall and Hall, 1974). A more complete picture of the results is provided by the analyses on arc sin proportion weight loss. The results for both treatment conditions combined were significantly different from the control conditon (F( 1,32) = 4.41, p < 0.05). This difference was primarily a function of the performance of subjects in the SC condition. SC’ subjects lost a greater
Individual Table
differences
1. Weight
changes
in self-reinforcement across
treatment
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361
and follow-up
Group Period Measure Pre- to post-treatment Loss in pounds Percentage body wt lost Pre-treatment to follow-up Loss in pounds Percentage body wt lost
Low SR SC
High SR EC
Low SR EC
MC
10.70
1.45
2.60
1.07
4.85
5.81
4.12
1.68
4.35
2.91
9.25
7.04
1.81
5.35
3.87
3.52
3.11
1.83
2.47
1.95
High SR SC
proportion of body weight than both EC subjects (F(1,32) = 32.83, p < 0.001) and MC subjects (F(1,32) = 5.87, p < 0.05). The EC condition was no more effective than MC (F( 1,32) < 1). Conclusions about the difference between SC and EC must be qualified by the fact that the interaction between treatment and SR group was highly significant (F(l,32) = 11.83, p < 0.01). As shown in Table 1, Low SR subjects did moderately well in both SC and EC programs. However, the results for High SR subjects differed greatly in the two programs. High SR subjects lost an average of 5.81% body weight (10.70 pounds) in the SC condition while losing only 1.68% (2.60 pounds) in the EC condition. This pattern of results was maintained through the follow-up period. The analysis on raw weight change again indicated that the SC condition was more effective than the EC condition (F( 1,32) = 14.01, p < 0.001) over the entire 14-week period. The Treatment x SR interaction was also significant (F(1,32) = 5.08, p < 0.05). The arc sin proportion analyses indicated that SC subjects manifested a greater reduction in body weight than both EC subjects (F(1,32) = 5.41, p < 0.05) and MC subjects (F(1,32) = 5.31, p < 0.05). The EC condition did not differ from MC (F(1,32) < 1). The interaction effect for this analysis approached significance. Pearson Product Moment correlation coefficients were calculated between weight loss and a number of pre-treatment demographic variables and post-treatment questionnaire responses. None of the pre-treatment variables (including age and motivation) were significantly correlated with weight loss. The self-reported application of the following program recommendations was significantly correlated with weight loss: setting a goal (1.= 0.67) p < 0.001) avoiding snacks (r = 0.43, p < 0.05) taking one helping at a time (r = 0.41) p < 0.05), and engaging in alternative activity to avoid eating (r = 0.41, p < 0.05). There has been some conjecture about the advisability of frequent weight checks given the small daily weight changes that can be achieved. Interestingly, there were significant negative correlations between weight loss and frequency with which subjects reported weighing themselves during the treatment period (I = -0.42, p < 0.05) and follow-up period (r = -0.38, p < 0.05). DISCUSSION
The results provide strong support for the general hypothesis that subject characteristics interact with treatment parameters. The significant interaction indicated that the effectiveness of the treatment programs was quite different for the two SR groups, and conversely, that the probability of weight-loss was a function of the treatment to which the subject was exposed. While this general finding was expected, the nature of the interaction was somewhat surprising. High SR subjects lost a substantial amount of weight in the SC program and an inconsequential amount of weight in the EC condition. In fact, High SR subjects in EC lost less than subjects in the control group. Given that EC consisted of SC combined with a financial contingency, it would appear that the contingency decreased the effectiveness of an otherwise effective program. There are several possible explanations of this finding. The FC procedure was imposed upon
subjects by the therapist as a presumably necessary condition for weight loss. Davison (19731 has suggested that behavior modification programs are susceptible to ‘counter control’ by patients: resistance to manipulation by the therapist despite the desire to change. If High SR subjects prefer. and characteristically emphasize self-control over their behavior, it is possible that they responded negatively to the emphasis on external control, to the particular. EC procedure employed. or to the fact that such control was imposed upon them. If they experienced any of these reactions. they might have engaged in ‘counter control’ as a response to being maIlipulated. This hyrpothesis presumes that subjects actively (albeit covertly) resisted the program. A more parsimonious explanation is that while there may have been a negative reaction to the EC procedure. the effects were indirect. Because of its high (negative) valance. the FC procedure generated a disproportionate amount of attention and distracted subjects from other. more effective components of the program (e.g., stimulus control precedures. SM). Some indirect support for this hypothesis is provided by Behack, Rozensky and Schwartz (1974). In a slightly different context. they also found that the addition of an ineffective program element could mitigate the effects of a viable treatment procedure. While further research is necessary to verify this finding, greater caution is advised in the construction of multi-component treatment packages. When presented with a smorgasboard of techniques, subjects are at least as likely to focus on ineffective as effective elements. The results of such a focus. as in this study. can be contratherapeutic. The Low SR subjects did moderately well in both treatment conditions. The FC procedure did not result in greater weight losses than the basic SC program. Conversely, FC did not reduce the effectiveness of the SC components. This is consistent with the hypothesis presented above for the High SR group. Low SR subjects would not be expected to respond affectively (either positively or negatively) to EC. The FC procedure would not. therefore. have a disproportionate impact on their response to the program. The overall differences in weight loss between High and Low SR subjects was not significant. primarily as a function of the significant interaction between SR group and treatment condition. It should be emphasized here that from the perspective of both individual differences in preference or ability and program demands, SC and EC exist along continua (Thoresen and Mahoney. 1974). Low SR subjects were not incapable of using SC, but were low relative to the specific group of Highs selected. Both treatment programs involved the application of both SC and EC; the EC program emphasized EC more than the SC program did. High SK subjects in the SC condition lost an average of 3.25 pounds ( I .69”,, body wt.) more than Low SR subjects in that condition. That difference amounts to almost one half pound per week, and is quite impressive given that subjects were classified simply on the basis of a median split of SR scores. It seems likely that an even greater difference would have been found if more disparate groups (e.g.. upper and lower thirds of the distribution) had been selected. These positive findings indicate that additional clinical and analogue research on SR differentiation is warranted. Clinical research should include applications with other populations as well as refinement of the assessment device. There are several questions that have been raised by these results aside from potential clinical utility. The first issue pertains to the specific parameters of the operationally defined SR responses secured on the memory task in this study, or the (time estimation) task used by Bellack ef al. (in press). These responses could represent the tendency to administer SR, stringency of standards for administration of SR. etc. There is also some suggestion that responses of this type are self-evaluations. rather than reinforcements (Bandura, 1971). A related issue is the specific nature of the relationship between responses on these tasks and performance in SC programs. Both SE and SR are fundamental components of SC behavior (Kanfer and Karoly, 1972). Deficits in either component could result in performance decrements in SC programs. In that regard it was reported above that several investigators have found a relationship between locus of control and weight loss. Bellack (Bellack. 1975, h: Bellack and Tilfman, 1974) has found that externals
Individual differences
in self-reinforcement
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363
(who lose less weight) are more dependent upon others for evaluation of their behavior and make less effective use of self-reinforcement than internals. He concluded that the IE scale is measuring an aspect of self-control behavior. The relationship of locus of control and weight can thus be viewed as support for the conclusions drawn from the present study: response to treatment is affected by pre-existing differences in SC behavior. The SC program was effective for both High and Low SR subjects. These results provided confirmation of previous findings that the pre-behavior monitoring technique can be a powerful adjunct to a basic stimulus control program. The applicability of this procedure for other clinical populations should be explored. The difference in performance between the SC and MC groups suggests that some minimal degree of external control is necessary, even for High SR individuals. That control could serve as a discriminative stimulus for SC and/or as a reinforcer prr se. The future use of FC procedures similar to the one employed in this study is contraindicated. Considerable effort is necessary for application of the technique and the effectiveness is questionable. In the present study, FC had either neutral or negative effects. Jeffrey (1974) did report positive results for FC during treatment, but the effects dissipated by the time of a follow-up. There are instances when some form of externally managed contingencies would be applicable (e.g.. a patient with gross SC deficits). Two modifications of the FC procedure employed here should be considered for those situations. First, an effort should be made to insure that the size of the monetary reinforcer is adequate. Second, reinforcements (or some representative such as points or tokens) should be administered on a considerably more immediate basis than once each week.
REFERENCES ABRAHMSJ. and ALLEN G. (1974) Comparative effectiveness of situational programming, financial pay-offs and group pressure in weight reduction. Behar. Therupy 5, 391-400. ABRAM~~NE. E. (1973) A review of behavioral approaches to weight control. Behar. Res. and Therapy 11, 547-546.
BALCHP. and Ross A. W. (1975) Predicting success in weight reduction as a function of locus of control: a unidemensional and multidemensional approach. J. consulr and c/k. Psycho/. 43, 119. BANDURAA. (1971) Self-reinforcement processes. In: The Narure of Reinforcement. (Ed. R. GLASER)Academic Press. New York.
BANDURAA. and KUPERSC. J. (1964) Transmission of patterns of self-reinforcement through modeling. J. ahnorm. sot. Psyehol. 69, 1-9. BELLA~KA. S. (1975a) Behavior therapy for weight reduction: an evaluative review. Ad&r. Behac. 1, 73-82. BELLACXA. S. Self-monitoring and self-reinforcement in weight reduction. Behar. Therapy, in press. BELLACKA. S. (1975b) Self-evaluation. self-reinforcement and locus of control. J. res. Person. 9. 158-167. BELLACKA. S.. GLANZ L. and SIMON R. Positive and negative covert reinforcement in the treatment of obesity. J. cnnsulr. clin. Ps~eho~., in press. BELLACKA. S. and R~ZENXY R. H. (1975) The selection of dependent variabies for weight reduction studies. J. Be/xx.
Tkercrpy crnd exp. Ps~chiaf. 6, 83-84.
BELLACKA. S., ROZENSKYR. H. and SCHWARTZJ. (1974) A comparison of two forms of self-monitoring in a behavioral weight reduction program. Behur. Therccpy 5, 523-530. BELLACKA. S., SCHWARTZJ. and ROZENS~YR. H. (1974) The contribution of external control to self-control in a weight reduction program. J. Behur. Ther. und esp. fs~,cb~~zi.5, 245250. BELLACKA. S. and TILLMANW. (1974) The effects of task and experimenter feedback on the self-reinforcement behavior of internals and externals. J. cnnstrlr and c/in. Psycho/. 42, 330-336. DAVISONG. C. (1973) Counter
