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UBC Theses and Dissertations

Effects of response habits on the performance of obese, average and fluctuator subjects Aves, Penelope Jill


The purpose of this study was to assess the relative influence of stimulus cues and response tendencies on the behavior of average and consistently or inconsistently overweight individuals. The female undergraduate volunteers who participated in the study were assigned to one of three weight groups on the basis of weight history, present weight, and triceps skinfold measurements. The three groups included consistently average, consistently overweight, and "fluctuator" subjects. This last group consisted of subjects whose weights over the past two years had varied between the average and overweight classifications. There were 20 subjects in each of the three groups. All subjects completed two experimental tasks and were also administered the Eysenck Personality Inventory (EPI), Form A. The first experimental task, used previously by Sikes, involved guessing the colors (black or red) of 120 consecutively presented cards. Seventy-five per cent of the first 90 cards in the series were black, while all of the remaining 30 cards were red. As expected, there were no performance differences between groups on the first 90 cards; however, on the last 30 cards consistently overweight participants made significantly more errors than either average or fluctuator subjects. This finding is consistent with Singh's deficit-in-response-inhibition hypothesis which maintains that overweight people have greater difficulty in changing established response tendencies than do people of average weight. It is noteworthy, however, that in the present study only people who had been consistently overweight for the past two years experienced more difficulty in changing their established responses. The second experimental task involved learning two paired associate word lists in an A-B/A-Br transfer paradigm. As expected, there were no performance differences between groups on the initial list. Contrary to expectations, however, there were also no differences between groups on the transfer list which required the suppression of previously established responses. Thus, in this situation consistently overweight subjects did not show the predicted deficit-in-response-inhibition effect. The results, then, offer partial support for Singh's interpretation of obesity in terms of differential response tendencies. No support is found for Schachter's interpretation which stresses the effects of external cues, since obese subjects did not show performance that was superior to that of average subjects at any point. Results from analyses of subjects' scores on the EPI indicated that there were no differences between the three weight groups on either extraversion or neuroticism. In addition to providing some support for Singh's hypothesis, the experimental findings in this study indicate that it is important to consider recent weight history as well as present weight when investigating behavioral differences between overweight and normal individuals. Implications of this research for treatment of overweight individuals were discussed.

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