Advice weighting as a novel measure for belief flexibility in people with psychotic-like experiences

Jumping to conclusions and bias against disconfirmatory evidence are two cognitive biases common in people with psychotic-like experiences and psychosis. However, many participants show comprehension problems doing traditional tasks; new paradigms with additional applied scenarios are thus needed. A large MTurk community sample (N = 1422) was recruited and subdivided into participants with high levels of psychotic-like experiences (at least 2 SD above the mean, n = 79) and participants with low levels of psychotic-like experiences (maximum 0.5 SD above the mean, n = 1110), based on the positive subscale of the Community Assessment of Psychic Experiences (CAPE). In the context of a judge-advisor system, participants made an initial estimate and then received advice that was either confirmatory or disconfirmatory. Participants then gave a new, possibly revised estimate and were allowed to seek additional advice. Participants with high levels of psychotic-like experiences gave their final assessment after receiving significantly less advice and were significantly more confident in their decision than participants with low psychotic-like experiences, in line with previous studies on jumping to conclusions and overconfidence. Contrary to the hypothesis and earlier studies, however, no deficit in belief revision was found. In fact, participants with high psychotic-like experiences weighted advice significantly higher in the condition with disconfirmatory advice, but only for the first advice they received. The increased weighting of a single piece of disconfirmatory advice can be explained by the hypersalience of evidence-hypothesis matches theory, according to which more weight is attached to the most recently available information.