Pizzas: or Square? Psychophysical Biases in Area Comparisons

Many product categories, from pizzas to real estate, present buyers with purchase decisions involving complex area judgments. Does a square look larger or smaller than a circle? How much smaller does a circle of 8-inch diameter look when compared to one with a 10-inch diameter? In this paper, we propose a psychophysical model of how consumers make area comparison judgments. The model involves consumers making effort-accuracy trade-offs that lead to heuristic processing of area judgments and systematic shapeand size-related biases. The model is based on four propositions: P1. Consumers make an initial comparison between two figures based on a single dimension; P2. The dimension of initial comparison-the primary dimension-is the one that is most salient to consumers, where salience is figure and context dependent; P3. Consumers insufficiently adjust an initial comparison using a secondary dimension, which we assume to be orthogonal to the primary dimension used for the initial comparison; and P4. The magnitude by which the initial comparison is adjusted is directly related to the relative salience of the secondary dimension versus the primary dimension. The model predicts that a single linear dimension inappropriately dominates the two-dimensional area comparison task and that contextual factors affect which linear dimension dominates the task. The relative use of the second dimension depends on its relative salience, which can be influenced in a variety of ways. The model extends the area estimation literature in cognitive psychology by exploring new biases in area estimation and is able to resolve controversial effects regarding which shape is perceived to be "bigger," the square or the circle, by incorporating contextual factors into model specifications. A set of six studies-five laboratory experiments and one field experiment-systematically test model predictions. Study 1 is a process study that shows that when two dimensions are available to make an area comparison judg0732-2399/01/2004/0405/$05.0