The intentionality bias in schizophrenia

• A cognitive bias could lead to over-attribution of intentionality in patients with schizophrenia.
• Task is to decide if a character acted intentionally or not in actions described by short sentences.
• Results highlighted the expected “overactive” intentionality bias in people with schizophrenia.
• People with schizophrenia could be unable to inhibit the automatic attribution of intentionality.

The tendency to over-interpret events of daily life as resulting from voluntary or intentional actions is one of the key aspects of schizophrenia with persecutory delusions. Here, we ask whether this characteristic may emerge from the abnormal activity of a basic cognitive process found in healthy adults and children: the intentionality bias, which refers to the implicit and automatic inclination to interpret human actions as intentional (Rosset, 2008, Cognition 108, 771–780). In our experiment, patients with schizophrenia and healthy controls were shown sentences describing human actions in various linguistic contexts, and were asked to indicate whether the action was intentional or not. The results indicated that people with schizophrenia exhibited a striking bias to over attribute intentionality regardless of linguistic context, contrary to healthy controls who did not exhibit such a general intentionality bias. Moreover, this study provides some insight into the cognitive mechanisms underlying this bias: an inability to inhibit the automatic attribution of intentionality.