Confirmation: What's in the evidence?

The difference between accommodated evidence (i.e., when evidence is known first and then a hypothesis is proposed to explain and fit the observations) and predicted evidence (i.e., when evidence verifies the prediction of a hypothesis formulated before observing the evidence) is investigated in this article. According to the purely logical approach of Bayesian confirmation theory, accommodated and predicted evidence constitute equally strong confirmation. Using a survey experiment on a sample of students, however, it is shown that predicted evidence is perceived to constitute stronger confirmation than accommodated evidence. The results show that predictions work as a signal about the scientists' (the proposer of the hypothesis) knowledge which in turn provides stronger confirmation.