Reasoning and delusion proneness: confidence in decisions

The present study was an investigation into the reasoning of delusion prone individuals. Seventy healthy individuals in the general population completed a measure of delusion proneness and engaged in 8 trials of difficult probabilistic reasoning tasks, 4 emotionally neutral and 4 emotionally salient, and were asked to report their level of confidence in their decisions. While delusion prone individuals did not request any fewer stimuli on reasoning tasks than did individuals who were not delusion prone, delusion prone individuals were more confident in their decisions on the neutral task than individuals who were not delusion prone and were more confident in their decision on the first trial, regardless of the type of stimuli presented. Further, despite requesting less information on neutral than salient tasks, delusion prone individuals reported equivalent confidence on both tasks. Delusion proneness and delusion onset may be related to overconfidence in decisions, particularly overconfidence in initial judgment.