Dynamic Sunk Costs: Importance matters when opportunity costs are explicit.

The sunk cost fallacy is a well-established phenomenon where decision makers continue to commit resources, or escalate commitment, because of previously committed efforts, even when they have knowledge that their returns will not outweigh their investment. Most research on the sunk cost fallacy is done using hypothetical scenarios where participants make a single decision to continue with a project or to abandon it. This paradigm has several limitations and has resulted in a relatively limited understanding sunk cost behavior. To address some of these limitations, we created a dynamic repeated choice paradigm where sunk costs are learned over time and opportunity costs are explicit. Over three experiments we show that the sunk cost fallacy depends on the relative a priori importance of the goal being invested in. We observed escalation of commitment only when the sunk cost domain is more important than alternatives (explicit opportunity costs), and participants showed de-escalation of commitment to the sunk costs domain otherwise.