Journal of Abnormal Psychology 1989, Vol. 98, No. 1,89-92 Copyright 1989 by the American Psychological Association, Inc. 0021-843X/89/S00.75 Restraint and Internal Responsiveness: Effects of Placebo Manipulations of Hunger State on Eating Todd F. Heatherton, Janet Polivy, and C. Peter Herman University of Toronto, Toronto, Ontario, Canada Restrained and unrestrained subjects were given a "vitamin" (placebo) prior to an ad-lib taste test. Subjects were either told nothing about the placebo or told that previous subjects had reported that the vitamin had made them feel either hungry or full. As predicted, restrained subjects, in two separate studies, behaved in accordance with placebo messages, eating more when given "hungry" messages than when given "full" messages. Unrestrained subjects showed an apparent reverse-pla- cebo effect; they ate less ice cream when given "hungry" information than when given "full" infor- mation. Hunger ratings did not parallel eating behavior; possible explanations for this discrepancy are considered. We conclude that unresponsiveness to internal hunger state, and an overreliance on external cognitive cues, characterizes restrained but not unrestrained individuals. Intuition tells us that most individuals eat when they are hun- gry and stop when they become sated. Disorders of eating, by the same token, are frequently regarded as disturbances of the normal associations between hunger and eating or between sati- ety and cessation. For instance, insensitivity to satiety sensa- tions—and a concomitant overreliance on external cues—was long held to play a cardinal role in the development of obesity (Schachter, 1968), and the denial of hunger sensations has long been thought to characterize those with anorexia nervosa (Bruch, 1973). Herman and Polivy (1980) have suggested that insensitivity to internal hunger cues (and an overreliance on external cues) may result when restrained individuals force themselves to ig- nore or override internal demands in their attempt to reduce food intake. For dieters, unresponsiveness to hunger signals may become habitual, and may generalize to related physical cues, including those associated with satiety. Choosing to ignore one's physical state in favor of cognitive regulation of eating— in keeping with a dietary quota (Polivy & Herman, 1985)—thus results in dieters' losing touch with how hungry they really are and how dependent they have become upon external or cogni- tive eating cues. If restrained eaters are mainly responsive to cognitive eating cues, they should be strongly affected by cognitive manipula- tions of hunger. Doerman and Kronenberger (1981) showed that a cognitive manipulation of perceived stomach state affects obese but not normal-weight individuals; obese subjects ate more peanuts when told that they had just consumed low-ex- pansion methyl cellulose capsules than when they were told they had consumed high-expansion capsules, whereas normal- weight subjects did not respond to the manipulation. Although We would like to thank the Natural Sciences and Engineering Re- search Council of Canada for their support. We would also like to thank Jonathan Freedman and Patricia Pliner for their valuable comments. Correspondence concerning this article should be addressed to Todd F. Heatherton, Department of Psychology, University of Toronto, To- ronto, Ontario, Canada M5S 1A1. methodological difficulties, including the absence of a proper control group, limited the interpretation of these results, a sim- ilar placebo design may provide a practical means of examining responsiveness to hunger/satiety sensations in normal-weight restrained and unrestrained eaters. We thus attempted a cognitive manipulation of hunger with restrained and unrestrained subjects, in which experimental subjects were told that they should expect (on the basis of previ- ous subjects' reports) to feel either hungry or full following in- gestion of a vitamin capsule. Control subjects were given no such expectation. Restrained eaters, presumed to be unrespon- sive to internal state (or more responsive to external cues), were expected to eat in accordance with experimental messages (i.e., more when told that previous subjects reported being hungry and less when told that previous subjects had reported that the pill made them full). Unrestrained subjects were not expected to show a placebo effect as they are presumed to eat in accor- dance mainly with internal state. Study 1 Method Subjects. One hundred and twenty-nine female undergraduates, ranging in age from 18 to 27 years, took part in this study in exchange for credit in an introductory psychology course. Nine subjects had to be discarded from the analyses for failure to follow experimental in- structions. On the basis of precedent (Polivy, Herman, & Howard, 1988), those scoring 16 or higher on the Restraint Scale were designated as restrained, and those scoring 15 or lower were classified as unre- strained. Approximately half of the subjects (58) filled out the Restraint Scale on a previous occasion, whereas the remainder filled out the Re- straint Scale immediately after the experiment. Procedure. Subjects were recruited for a study examining the effects of vitamins (actually a lactose placebo pill) on perceptual mechanisms. Following a minimum 2-hr deprivation period, subjects came to the lab, filled out initial hunger ratings, and were told, "This vitamin is a new megavitamin that has recently been developed. It has been tested for safety and is, of course, perfectly safe." They were then given one of three experimental messages: 89