Influence of clear versus ambiguous normative information on food intake

Two studies were conducted in order to examine the conditions under which social norms operate to control people's otherwise prepotent response to maximize eating. The social-normative model of eating assumes that people will follow one of two possible norms for “appropriate” eating behavior: the norm to eat minimally and the norm to avoid eating excessively. In Experiment 1, it was predicted that amounts eaten would be bimodally distributed (with the modes at or just below the two amounts chosen to represent minimal and excessive eating). Instead, most participants ate considerably more than either of the norms presented. Experiment 2 was intended to test the following explanation for these results: exposure to ambiguous norms liberated participants from normative constraints and led them to overeat. Experiment 2 demonstrated that exposure to clear norms in the same situation exerted a braking effect on overeating. We conclude that individuals are more likely to eat in accordance with their own desires when they cannot perceive that others are following a clear pattern of eating behavior and social norms are, therefore, not apparent.