The acuity of vice: Attitude ambivalence improves visual sensitivity to increasing portion sizes

A rapid increase in the size of food portions has underlined the importance of understanding consumers' ability to accurately perceive portion sizes. Drawing on research on motivated perception, we posit that attitude ambivalence (simultaneously desiring a food and perceiving it as unhealthy) enhances visual sensitivity to increasing portion sizes. We manipulate or measure attitude ambivalence in three experimental studies conducted among children and adults and find that visual sensitivity is driven not simply by desire but by the coexistence of desire and perceived unhealthiness of the food (e.g., for hedonic food and among restrained eaters). Our findings suggest that framing foods as vices improves the estimation of portion sizes among health-conscious people.