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

Objective: To assess residents' propensity to display the sunk-cost effect, an irrational decision-making bias, in medical treatment decisions; and to compare residents' and undergraduates' susceptibility to the bias in non-m edical, everyday behaviors. Design: Cross-sectional, in-person survey. Setting: Louisiana State University, two locations: Medical Center-Baron Ro uge 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 pr esent 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 residents' ratings of whether to continue or switch me dical treatments were not influenced by the amount of the initial investmen t (p's > 0.05). Second, residents' reasoning was more normative in medical than in non-medical situations, in which it paralleled that of undergraduat es (p's < 0.05). Conclusions: Medical residents' 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, th e residents did demonstrate a sunk-cost effect in evaluating non-medical si tuations. Thus, any advantage in decision making that is conferred by medic al training appears to be domain specific. (C) 1999 Elsevier Science Ltd. A ll rights reserved.