Most prior research on the compromise effect has focused on single rather than multiple choices. This research investigates the potential effects of purchase quantity on the compromise effect. We propose that the share of the middle option in a trinary choice set decreases as the purchase quantity increases, because people tend to employ a balance heuristic to distribute their multiple choices among the available options to achieve a balanced state and to satisfy their variety-seeking tendency. Furthermore, we propose that the need for justification and an optimal stimulation level moderate the relationship between the number of purchase items and the compromise effect. These proposed hypotheses are supported by results from three experiments.
