The Visual Illusions of Food: Why Plates, Bowls, and Spoons Can Bias Consumption Volume

Abstract

Objective Although the vast majority of our food is consumed from plates, bowls, and spoons, there still is little evidence as to how their size may influence consumption behavior. We investigate how the size of plates and spoons influences serving and consumption volume. Based on the Ebbinghaus-Titchener size-contrast illusion, we show people tend to underestimate the amount they dish into large plates and bowls Two field studies show that when children and adults serve themselves, as a result of a size-contrast illusion, they serve and consume more cereal when given a larger plate compared to those given a smaller plate, even though they perceive the opposite to be true. In a third study, these findings are generalized by showing comparable effects of spoon size when consumers serve cough medicine on teaspoons, tablespoons and serving spoons. Finally, we examine the interaction effect of plate and spoon size on the serving and consumption volume of ice cream.