Abstract

Anchoring refers to the finding that if people are presented with an initial estimate, their subsequent estimate of a quantity will be biased towards the initial estimate. This finding has been used in the context of overeating, by serving foods on smaller plates. Here we investigate more explicit anchoring effects on calorie estimation. Participants (N=118) were asked (1) to indicate whether the calorie content of foods was below or above a given number (the anchor), (2) to estimate the calorie content of that food, and (3) to indicate how confident they were about the estimate. Nine foods were tested, which either had (1) no anchor, (2) a high anchor, or (3) a low anchor (with anchors either 30% or 70% larger or smaller than the actual calorie content). Results showed that high anchors led to overestimations and low anchors to underestimations, but no effect of anchor size was found. Anchoring was not systematically affected by the confidence in the estimates, but confidence increased with actual calorie content. The findings suggest that adding a statement ‘less than … calories’ on food labels may make people overestimate the calorie content of the food.