Ex post ≠ ex ante: Determining liability in hindsight.

Participants in three conditions (foresight, hindsight, and a modified hindsight condition designed to ameliorate the hindsight effect) assessed whether a municipality should take, or have taken, precautions to protect a riparian property owner from flood damage. In the foresight condition, participants reviewed evidence in the context of an administrative hearing. Hindsight participants reviewed parallel materials in the context of a trial. Three quarters of the participants in foresight concluded that a flood was too unlikely to justify further precautions-a decision that a majority of the participants in hindsight found to be negligent. Participants in hindsight also gave higher estimates for the probability of the disaster occurring. The debiasing procedure failed to produce any significant differences from the regular hindsight condition. The results suggest that absent an effective debiasing technique, risk assessments made in foresight will be judged harshly in hindsight.