Rationality in medical treatment decisions: is there a sunk-cost effect?

Objective: To assess residentsʹ propensity to display the sunk-cost effect, an irrational decision-making bias, in medical treatment decisions; and to compare residentsʹ and undergraduatesʹ susceptibility to the bias in non-medical, everyday behaviors. Design: Cross-sectional, in-person survey. Setting: Louisiana State University, two locations: Medical Center-Baton Rouge and Main Campus-Psychology Department. Participants: Internal medicine and family practice residents (N=36, Mdn age=27) and college undergraduates (N=40, Mdn age=20). Measurements and main results: Residents evaluated medical and non-medical situations that varied the amount of previous investment and whether the present decision maker was the same or different from the person who had made the initial investment. They rated reasons both for continuing the initial decision (e.g., stay with the medication already in use) and for switching to a new alternative (e.g., a different medication). There were two main findings: First, the residentsʹ ratings of whether to continue or switch medical treatments were not influenced by the amount of the initial investment (pʹs>0.05). Second, residentsʹ reasoning was more normative in medical than in non-medical situations, in which it paralleled that of undergraduates (pʹs<0.05). Conclusions: Medical residentsʹ evaluation of treatment decisions reflected good reasoning, in that they were not influenced by the amount of time and/or money that had already been invested in treating a patient. However, the residents did demonstrate a sunk-cost effect in evaluating non-medical situations. Thus, any advantage in decision making that is conferred by medical training appears to be domain specific.