Temporal Order Judgments in Schizophrenia and Bipolar Disorders – Explicit and Implicit Measures

Ordering events in time is essential for the understanding of causal relationships between successive events. Incorrect causal links can lead to false beliefs and an altered perception of reality. These symptoms belong to psychosis, which is present in schizophrenia (SZ) spectrum and bipolar (BP) disorder. Experimental results show that patients with SZ have an altered perception of temporal order, while there are no data in patients with BP. We investigated the ability of patients with SZ, BP, and controls to judge the order of stimuli with a 100-ms Stimulus Onset Asynchrony (SOA), and how such large asynchronies facilitate temporal order judgments for small asynchronies. Explicit temporal order effects suggest that patients with SZ perform worse at a long SOA (100 ms) as compared to controls, whereas patients with BP show no difference compared to controls or to patients with SZ. Implicit order effects reveal improved performances in case of identical as compared to different relative order between two successive trials for all groups, with no differences between the groups. We replicated explicit order impairments in patients with SZ compared to controls, while implicit effects appear to be preserved. This difficulty for patients to consciously order stimuli in time might be understood under the light of the loosening-of-associations phenomenon well described in SZ. Further, we showed that patients with BP do not reveal such an explicit order impairment which is consistent with phenomenological descriptions, suggesting a difference in time experience in patients with SZ and BP.