ABSTRACT
Studies in health, nutrition science, psychology, and marketing have established that quantity judgments drive a host of consumption decisions including consumption quantity, product choice, and willingness to pay. Despite the increased availability of size information on food packaging and restaurant menus, upwards of 70" of consumers do not check this information to make quantity judgments. This chapter identifies five biases related to the underestimation of package and portion size changes, the dimensionality of size changes, the directionality of size changes, labeling effects, and affective influences, which hinder the accuracy of size estimations as well as healthy consumption choices. Since the underestimation bias occurs regardless of consumers' weight and nutrition expertise, even professional dieticians are susceptible to the bias, which would suggest that visual biases are hardwired. The dimensionality bias occurs because estimating volume change requires individuals to integrate information across three product dimensions – in a multiplicative fashion – hence the estimation task is increasingly complex.
