Our most confident memories can be completely wrong

How certainty leads us astray

Imagine you are a game show contestant and the host asks a simple question: “The island of Corsica belongs to which country?”

If you’re like most people, you’re probably thinking “Italy.” If asked if that were your final answer, you’d say yes — you’re probably confident “Italy” is the answer.

Unfortunately, though, your confident memory is wrong. Corsica belongs to France.

Over the last five years, I’ve collaborated with Dr. Henry L. Roediger, III to investigate the degree to which our confidence predicts the accuracy of our memories (or our knowledge about the world, as in the example above). The main message of this research — recently published in the journal Psychological Science— is that a subjective sense of high confidence is only sometimes predictive of accuracy. In some cases, high confidence in an answer can mean we’re very likely to be correct. On the other hand, high confidence can sometimes be predictive of an incorrect answer.

In our study, we had undergraduate students memorize words belonging to different categories. For example, students may have studied the words “oriole,” “eagle,” and “cardinal” from a “birds” category. Later, we gave them a recognition memory test, meaning we presented…