Restraint and internal responsiveness: effects of placebo manipulations of hunger state on eating

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-placebo effect; they ate less ice cream when given "hungry" information than when given "full" information. 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.