Temporal context and the organisational impairment of memory search in schizophrenia

Introduction. An influential theory of schizophrenic deficits in executive function suggests that patients have difficulty maintaining and utilising an internal contextual representation, whose function is to ensure that stimuli are processed in a task-appropriate manner. In basic research on episodic memory, retrieved-context theories propose that an internal contextual representation is critically involved in memory search, facilitating the retrieval of task-appropriate memories. This contextual machinery is thought to give rise to temporal organisation during free recall: the tendency for successive recall responses to correspond to items from nearby positions on the study list. If patients with schizophrenia have a generalised contextual deficit, then this leads to the prediction that these patients will exhibit reduced temporal organisation in free recall. Methods. Using a combination of classic and recently developed organisational measures, we characterised recall organisation in 75 patients with schizophrenia and 72 nondisordered control participants performing a multi-trial free-recall task. Results. Patients with schizophrenia showed diminished temporal organisation, as well as diminished subjective organisation of their recall sequences relative to control participants. The two groups showed similar amounts of semantic organisation during recall. Conclusions. The observation of reduced temporal organisation in the patient group is consistent with the proposal that the memory deficit in schizophrenia can be characterised as a deficit in contextual processing.