To explore a cognitive bias-Jumping to Conclusions-in patients with schizophrenia and to compare with non-psychotic siblings and healthy controls by means of the Picture Decision Task (PDT).

42 patients with schizophrenia, 20 non-psychotic siblings and 77 healthy controls were compared in the PCT. This task consists of showing drawings of common objects that are displayed on a computer screen in decreasing degrees of fragmentation: new features are added in eight successive stages, until the entire object is eventually manifest. There are two kinds of trials (“cued” and “uncued”; that is, with and without interpretative clues). According to the responses, five parameters were calculated: Jumping To Conclusions at first stage-that is, with the very first drawing-(JTC-1), Plausibility Rating at first stage (PR-1), Draws To Decision (DTD), Time Response at first stage (TR-1) and Time Response for Draw to Decision (TR-DTD)

In comparison with siblings and controls, more of the schizophrenia patients made a definitive decision at the first stage (represented by a significantly higher JTC-1), and they showed a higher Plausibility Rating (represented by a higher PR-1) than siblings and controls. For the uncued trials, patients needed fewer stages (a lower DTD) when making a decision than siblings (5.53±0.20 vs. 7.04±0.28; p=0.001) and controls (5.53±0.20 vs. 6.83±0.14; p=0.001).

These results suggest that patients make quick decisions with a high level of conviction and may manifest a data-gathering bias. Our results may indicate some degree of faulty appraisal and an inability to tolerate ambiguity when faced with decision-making.