Sunk costs are irrecoverable investments that should not influence decisions, because decisions should be made on the basis of expected future consequences. Both human and nonhuman animals can show sensitivity to sunk costs, but reports from across species are inconsistent. In a temporal context, a sensitivity to sunk costs arises when an individual resists ending an activity, even if it seems unproductive, because of the time already invested. In two parallel foraging tasks that we designed, we found that mice, rats, and humans show similar sensitivities to sunk costs in their decision-making. Unexpectedly, sensitivity to time invested accrued only after an initial decision had been made. These findings suggest that sensitivity to temporal sunk costs lies in a vulnerability distinct from deliberation processes and that this distinction is present across species.
Wednesday, July 25, 2018
When persistence doesn't pay - the sunk cost bias.
Sweis et al. show that sensitivity to time invested in pursuit of a reward occurs similarly in mice, rats, and humans. All three display a resistance to giving up their pursuit of a reward in a foraging context, but only after they have made the decision to pursue the reward. They suggest that there are two independent valuation processes, one assessing whether to accept an offer and the other — the one that is susceptible to sunk costs — assessing whether to continue investing in the choice. Their abstract: