Under what circumstances do patients with schizophrenia jump to conclusions? A liberal acceptance account.

BACKGROUND: A consistent body of studies suggests that schizophrenia patients are extremely hasty when making decisions, and generally opt for the strongest response alternative. This pattern of results is primarily based on studies conducted with the beads task, which requires participants to determine from which of two possible jars a series of beads has been drawn. We have recently proposed a liberal acceptance (LA) bias to account for decision-making biases in schizophrenia, which claims that under heightened ambiguity the jump to conclusions (JTC) bias is abolished in schizophrenia.
METHODS: A total of 37 schizophrenia patients were compared with 37 healthy controls on different versions of the beads paradigm. For the first task, participants were required to rate the probability that a bead was being drawn from one of two jars, and had to evaluate after each bead whether the amount of presented information would justify a decision. The second task was a classical draws to decision experiment with two jars. The third task confronted participants with four possible jars. If JTC was ubiquitous in schizophrenia hasty convergence on one alternative would be predicted for all three tasks. In contrast, the LA account predicts an abolishment of the JTC effect in the final task.
RESULTS: Tasks 1 and 2 provide further evidence for the well-replicated JTC pattern in schizophrenia patients. In accordance with the LA hypothesis, no group differences were detected for task 3. DISCUSSION: The present results confirm that JTC is not ubiquitous in schizophrenia: in line with the LA account a JTC bias in schizophrenia occurred under low but not high ambiguity. LA may partly explain the emergence of fixed, false beliefs.