Just as I expected? Hindsight bias for the outcome of a national referendum is moderated by outcome valence and surprise

When people learn that an event has occurred, they often report that they expected it all along. The present study explored this "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 bias was predicted by voting choice: People on the losing side exhibited a classic hindsight bias, and remembered believing the outcome to be roughly 16% more likely than they originally reported. In contrast, people on the winning side exhibited a weak reversal of the typical bias. Hindsight bias was moderated by feelings of surprise in both groups. This study suggests that individuals on the losing side of political campaigns may be especially likely to misremember their prior expectations if the outcome is disappointing but not unexpected.