Just as I expected? Hindsight bias for the outcome of a national referendum depends on outcome valence and surprise

When people learn that an event has occurred, they often report that they expected it all along—a phenomenon called “hindsight bias.” The present study explored hindsight bias for the outcome of a national referendum on abortion. Participants rated the probability of the referendum passing one week before polling day, and then recalled their original estimates one week and one year post-referendum. The magnitude and direction of hindsight bias was affected by voting choice: People on the losing side exhibited a classic hindsight bias, and remembered having believed the outcome to be more likely than they originally reported. In contrast, people on the winning side exhibited a weak reversal of the typical bias. The magnitude of hindsight bias was moderated by feelings of surprise and previous informal campaigning. This study suggests that individuals on the losing side of important political campaigns may be especially likely to misremember their prior expectations.