Follow-up of Effects of Choice of Mediator and Target of Reinforcement on Weight Loss

ALLEN C. ISRAEL AND ANTHONY J. SACCONE

State Umvel ~ttv o f New York at Albany

This study reports differential maintenance of weight loss at 3 and 12 months following the end of treatment effects reported In an earlier study Clients origi- nally assigned to either a basic stimulus control treatment condition or the basic program plus one of four reinforcement conditions" reinforcement by therapist for weight loss. reinforcement by therapist for change in eating behavior, reinforce- ment by a significant other for weight loss, or relnforcementby a significant other for eating behavior change returned for weigh-ins at these times Results indicated the importance of appropriate target (eating behavior change) and mediator (sig- nificant other) for maintenance of weight loss Reinforcement by a significant other for eating behavior change produced the most persistent loss of weight

S a c c o n e and Is rae l (1978) i nves t iga t ed the ef fec ts of m e d i a t o r and ta rge t o f r e i n f o r c e m e n t on weight loss in the c o n t e x t o f a s t imulus con t ro l t r e a t m e n t package . It was sugges ted tha t the fa i lure to find i nc r emen ta l e f fec ts o f m o n e t a r y r e i n f o r c e m e n t in p r ev ious s tud ies (e .g . , A b r a h m s & Al len , 1974) which have e m p l o y e d weight r educ t i on p r o g r a m s s imi lar to tha t d e s c r i b e d by S tuar t and Davis (1972) may have been due to the se l ec t ion o f weight loss r a the r than ea t ing b e h a v i o r as a ta rge t for rein- f o r c e m e n t . F u r t h e r m o r e , as sugges ted e l s e w h e r e (e .g . , T h a r p & W e t z e l , 1969), it was e x p e c t e d that r e w a r d by a s ignif icant o t h e r r a the r than by the t he rap i s t wou ld be fac i l i t a t ive of change . Both o f these h y p o t h e s e s we re s u p p o r t e d , as i nd i ca t ed by weight loss at the end of t r e a t m e n t . The p r e s e n t p a p e r r epo r t s the f indings ob t a ined f rom both 3- and 12-month fo l low-up weigh- ins for these same c l ients .

In the or iginal s tudy ( S a c c o n e & I s rae l , 1978), 48 w o m e n and 1 man were r a n d o m l y ass igned f rom st ra t i f ied b l o c k s b a s e d on p e r c e n t a g e over - weight to one o f seven g roups : (a) p r o g r a m only with mon i to r ing o f w e i g h t - - P W , (b) p r o g r a m only with mon i to r ing o f ea t ing b e h a v i o r - - P B , (c) p r o g r a m with r e i n f o r c e m e n t by the rap i s t for weigh t l o s s - - T W , (d) p r o g r a m with r e i n f o r c e m e n t by the rap i s t for ea t ing b e h a v i o r c h a n g e - - T B ,

Requests for reprints should be sent to Allen C Israel, Department of Psychology, State University of New York at Albany, 1400 Washington Ave, Albany, NY 12222.

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0005-7894/79/020260-06501.00/0 Copyright © 1979 by Assoclatmn for Advancement of Behavior Therapy MI rights of reproduction m any form reserved

REINFORCEMENT AND WEIGHT LOSS 261

(e) program with reinforcement by significant other for weight Ioss--SW, (f) program with reinforcement by significant other for eating behavior change--SB, or (g) no-treatment control. Data for all seven groups was available and reported both prior to and at the end of the eight-session treatment program. Each treatment group showed a statistically sig- nificant weight loss over the 9-week period, while the control group showed a nonsignificant weight gain. In addition, Saccone and Israel (1978) found that the effectiveness of the basic program was enhanced by the addition of monetary reinforcement when such reinforcement was contingent upon changes in eating behavior. It was suggested that in behavioral weight reduction programs, focusing on weight loss may in fact obscure the important point of the program, which is to alter eating habits. The group which received reinforcement from a significant other for behavior change demonstrated the greatest weight loss. It was predicted that this effect might become more pronounced over time, since rein- forcement by significant others could continue after program termination, while reinforcement by the therapist necessarily ended at program termi- nation. To test this prediction, and to note the differential maintenance of weight loss among the treatment groups, long-term follow-up data were obtained.

METHOD

To receive the remainder of their $35 deposit (i.e., the amount not already contingently returned during the program), clients in the treat- ment groups were required to return for weigh-ins at 3 and 12 months after post-treatment assessment. Control group clients received treatment (as payoff for returning for the post-test weigh-in) thus no control group data were available at follow-up assessments. Of the 44 clients in the six treatment groups, 38 (86%) were available for all weigh-ins. The largest attrition occurred in the TW group: one client changed her residence to a distant city, while two other clients became pregnant during the follow-up period. In the SW group, one client became pregnant, while one other simply refused to come in for the final weigh-in. The final client who was not available for follow-up was from the PB group, the reason again being pregnancy. There appears to be no relationship between success in the program and attrition, and of the six explanations from drop-outs, five were obviously unrelated to the treatment conditions.

RESULTS

The mean weights, standard deviations, and n for all groups at the four data collection points are presented in Table 1. A 2(Target) × 3(Mediator) × 3(Repeated Measures) analysis of covariance with pretreatment weight as the covariate was conducted for the six treatment groups. This and all other analyses were conducted employing only those individuals present for all weigh-ins (38). A significant main effect for the repeated measures factor, F(2, 64) = 3.86, p < .03, indicated an overall difference in mean

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263 REINFORCEMENT AND WEIGHT LOSS

CONTROL- X

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PRE POST 3MOS 12MOS TIME

FIG. 1 Covarlance-adjusted mean weights for all groups

weight at the different assessment times. The main effect for target ap- proached significance, F(1, 31) = 3.90, p < .057, suggesting the superior- ity of groups focusing on behavior change over groups focusing on weight loss. For graphic comparisons, the covariance-adjusted mean weights at each of the four assessment points (pretest, post-test, 3- and 12-month follow-up) and for the control group at pretest and post-test are shown in Fig. 1.

The remaining analyses were performed via planned comparisons of covariance-adjusted means, based on the preceding ANCOVA. Since these analyses necessitated the use of a pooled error term to assess effects involving repeated measures, conservative tests were conducted using corrected significance levels (Kirk, 1968). For two-tailed tests, the con- servative critical t-values for p -- .05 and p = .01 are 2.03 and 2.71, respectively.

Planned comparisons at the 3-month follow-up indicated that overall, reinforcement did not result in greater maintenance of weight loss. How- ever, reinforcing eating behavior change (TB and SB) and reinforcing and/or monitoring eating behavior change (TB, SB, and PB) both resulted in better maintenance of weight loss than reinforcing weight loss (TW and SW) or reinforcing and/or monitoring weight loss (TW, SW, and PW), respectively, t = 4.23, p < .01 and t = 4.30, p < .01. In addition, clients experiencing the involvement of a significant other maintained their weight losses better than those who had received reinforcement from the therapist, t = 2.52, p < .05. The clients who received reinforcement from a significant other for eating behavior change maintained weight losses better than did all other groups, t = 4.61, p < .01.

Planned comparisons at the 12-month follow-up again indicated that, overall, monetary reinforcement did not result in greater maintenance of weight loss than the basic stimulus control program alone. Again, how- ever, reinforcing eating behavior change and reinforcing and/or monitor-

264 ISRAEL AND SACCONE

ing eating behavior change both resulted in better maintenance of weight loss, respectively, than reinforcing weight loss or reinforcing and/or monitoring weight loss, t = 3.54,p < .01 and t = 2.92,p < .01. Unlike the 3-month follow-up, at 12 months following program termination there was no overall difference in weight loss between clients in the therapist and significant other conditions However , the clients who received rein- forcement from a significant other for eating behavior change continued to maintain greater weight loss than all other groups, t = 4.18, p < .01.

A weight reduction index (Pretest weight - 12 month weight/ideal weight) produced results parallel to those described above. The mean index for each group was as follows: PW = .0247, PB = .0240, TW = .0064, TB = .0534, SW = .0145, and SB = .0840.

DISCUSSION It is clear from the present results that reinforcement by a significant

other for changes in eating behavior enhances the effectiveness of be- havioral weight reduction programs of the variety suggested by Stuart and Davis (1972). It would seem that reinforcement during the treatment program for changes in the chent 's eating habits focuses the individual's attention upon patterns of eating. The effect produced by focusing on behavior would also appear to persist after the actual program ends and thereby facilitate the maintenance of weight loss. The present pattern of results would suggest that this procedure may be more effective in pro- ducing lasting weight loss, at least in part, because it focuses attention on eating behavior, which is relevant to the proximal goals of stimulus control programs, and minimizes the importance of immediate weight loss, which is often a distraction for weight-conscious clients.

The use of a significant other as the mediator of monetary reinforce- ment for behavior change was the most effective condition for promoting durable weight loss. It would therefore seem that individuals in the client 's natural environment can continue to facilitate changes in the client 's behavior produced by the basic program and the reinforcement procedure when the clear focus of attention for both the client and the significant other is on eating habits. The mere presence of a significant other, however , is not sufficient to enhance weight loss, and it is impor- tant that appropriate target behaviors be chosen. An inappropriate target can lead to inefficient use of the significant other, and possibly create confusion for the client regarding the goal of treatment.

Of course, the above conclusions are made within the context of treat- ment results which are clearly less than ideal. Clients did not achieve ideal body weight by the end of treatment nor did any treatment produce continued weight loss. Thus, a significant challenge clearly remains for behavioral weight loss prog(ams.

A final note concerns the extent of training time devoted to significant others in a weight loss program. The present program allocated one session for the training of significant others (who were usually spouses) in

REINFORCEMENT AND WEIGHT LOSS 265

bas ic c o n t i n g e n c y m a n a g e m e n t and b e h a v i o r m o n i t o r i n g / r e c o r d i n g tech- n iques . This 1-hr s e s s ion was the on ly c o n t a c t the s ignif icant o t h e r had with the t he r ap i s t s , and a l though this was a d e c i d e d l y e c o n o m i c a l ap- p r o a c h , it is u n c l e a r w h e t h e r i n c r e a s e d i n v o l v e m e n t o f the s ignif icant o t h e r in the p r o g r a m could fu r the r e n h a n c e the o b s e r v e d effect . This r e m a i n s a po t en t i a l l y frui t ful a r ea for fu r the r r e sea r ch .

REFERENCES Abrahms, J L., & Allen, G. J. Comparative effectiveness of situational programming,

financial pay-offs, and group pressure in weight reduction. Behavior Therapy, 1974, 5, 391-400.

Kirk, R. E. Experimental design: Procedures for the behavioral sciences. Belmont, CA Wadsworth, 1968.

Saccone, A J., & Israel, A. C. Effects of experimenter versus significant other-controlled reinforcement and choice of target behavior on weight loss. Behavior Therapy, 1978, 9, 271-278.

Stuart, R. B., & Davis, B. Slim chance in a fat world Champaign, ILL. Research Press, 1972.

Tharp, R. G., & Wetzel, R. J Behavior modification in the natural envu'onment New York: Academic Press, 1969

RECEIVED" March 28, 1978 FINAL ACCEPTANCE" July 18, 1978