Predicting vs. guessing: the role of confidence for pupillometric markers of curiosity and surprise.

Asking students to generate a prediction before presenting the correct answer is a popular instructional strategy. This study tested whether a person's degree of confidence in a prediction is related to their curiosity and surprise regarding the answer. For a series of questions about numerical facts, participants ( N  = 29) generated predictions and rated their confidence in the prediction before seeing the correct answer. The increase in pupil size before viewing the correct answer was used as a physiological marker of curiosity, and the increase in pupil size after viewing the correct answer was used as a physiological marker of surprise. The results revealed that the pupillometric marker of curiosity was most pronounced if students were slightly more confident in their prediction than usual, and it was lower for predictions made with either very high or very low confidence. Furthermore, the results showed that high-confidence prediction errors and low-confidence correct responses yielded a pupillary surprise response, suggesting that highly unexpected results evoke surprise, independent of the correctness of the prediction. Together, results suggest that confidence in a prediction plays an important role in the occurrence of epistemic emotions such as curiosity and surprise.