The sensory sampling model (SESAM, P. Juslin & H. Olsson, 1997) accounts for the underconfidence observed in sensory discriminations with pair-comparisons. In the present study the model is applied to a single-stimulus task and a comparison is made with pair- comparisons. The model predicts that in the single-stimulus condition training with feedback should lead to poorer calibration with more underconfidence. In pair-comparison the feedback should have little or no effect on calibration. The results confirm these predictions.

Reasonable rational information processing is important in people’s in everyday decision-making. A number offeatures affect how environmental messages are processed, including the presentation format and the reliability of the informa-tion source. One way to measure the importance assigned to the source reliability is to frame the question in terms of Bayes’theorem (Hahn & Harris, 2009). In two online experiments, we investigated how people process environmental messages in aBayesian integration task where the participants rate the probability of an energy crisis. The information about the prior, like-lihood ratio, and source reliability were presented either sequentially or simultaneously. The results showed that, as prescribedby Bayes’ theorem, participants integrated the sentences multiplicatively. However, with sequential presentation they assignedmore weight to source reliability, and this effect remained when the source reliability was presented next to last, suggesting thatparticipants assigned more weight to the source regardless of its position.