The contribution of hypersalience to the “jumping to conclusions” bias associated with delusions in schizophrenia

Abstract

7Background: Previous schizophrenia research involving the "beads task" has suggested an association between delusions and 2 reasoning biases: (1) "jumping to conclusions" (JTC), whereby early, resolute decisions are formed on the basis of little evidence and (2) overadjustment of probability estimates following a single instance of disconfirmatory evidence. In the current study, we used a novel JTC-style paradigm to provide new information about a cognitive operation common to these 2 reasoning biases. Methods: Using a task that required participants to rate the likelihood that a fisherman was catching a series of black or white fish from Lake A and not Lake B, and vice versa, we compared the responses of 4 groups (healthy, bipolar, nondelusional schizophrenia and delusional schizophrenia) when we manipulated 2 elements of the Bayesian formula: incoming data and prior odds. Results: Regardless of our manipulations of the Bayesian formula, the delusional schizophrenia group gave significantly higher likelihood ratings for the lake that best matched the colour of the presented fish, but the ratings for the nonmatching lake did not differ from the other groups. Limitations: The limitations of this study include a small sample size for the group of severely delusional patients and a preponderance of men in the schizophrenia sample. Conclusion: Delusions in schizophrenia are associated with hypersalience of evidence-hypothesis matches but normal salience of nonmatches. When the colour of the incoming data is uniform (fish of only one colour), this manifests as JTC early in a series, and when the colour of incoming data varies (both black and white fish), this manifests as an overadjustment midseries. This account can provide a unifying explanation for delusion-associated performance patterns previously observed in the beads task in schizophrenia.

Preserved, deteriorated, and premorbidly impaired patterns of intellectual ability in schizophrenia.

“…Biased probabilistic reasoning was measured with a recent modification (Speechley, Whitman, & Woodward, 2010) of the standard 'jumping to conclusions' task initially developed by Garety and colleagues (Garety et al, 1991). In this probabilistic reasoning task (also known as the "Beads Task"), subjects judged which of two jars a sequence of coloured beads had been taken from.…”

Metacognitive and social cognition training (MSCT) in schizophrenia: A preliminary efficacy study

“…Jumping to conclusion (JTC) bias was measured using the fish task (Moritz et al, 2010a;Speechley et al, 2010). Participants were shown two lakes with two different colors of fish in opposite ratios (80% and 20%).…”

Reduced activation in the ventral striatum during probabilistic decision-making in patients in an at-risk mental state

“…This task requests a probabilistic decision after a variable amount of stimuli, and JTC is usually defined as requiring only 1-2 stimuli to make a decision. [3][4][5] The theory of "disturbed error-dependent updating of inferences and beliefs about the world" in patients with schizophrenia 6 and findings on the JTC bias suggest that metacognitive impairments play a relevant role in the develop ment of delusions. [7][8][9][10][11] Furthermore, limited data gathering and the tendency to disregard evidence were recently found to be maintaining factors for delusions.…”