a1 Institute of Psychiatry, Kings College London, London, UK
a2 School of Psychology, University of Exeter, Exeter, UK
a3 Institute of Neurology, University College London, London, UK
a4 Division of Neuroscience and Mental Health, Imperial College London, London, UK
Background Previous studies have shown that patients with schizophrenia are impaired on executive tasks, where positive and negative feedbacks are used to update task rules or switch attention. However, research to date using saccadic tasks has not revealed clear deficits in task switching in these patients. The present study used an oculomotor ‘rule switching’ task to investigate the use of negative feedback when switching between task rules in people with schizophrenia.
Method A total of 50 patients with first episode schizophrenia and 25 healthy controls performed a task in which the association between a centrally presented visual cue and the direction of a saccade could change from trial to trial. Rule changes were heralded by an unexpected negative feedback, indicating that the cue-response mapping had reversed.
Results Schizophrenia patients were found to make increased errors following a rule switch, but these were almost entirely the result of executing saccades away from the location at which the negative feedback had been presented on the preceding trial. This impairment in negative feedback processing was independent of IQ.
Conclusions The results not only confirm the existence of a basic deficit in stimulus–response rule switching in schizophrenia, but also suggest that this arises from aberrant processing of response outcomes, resulting in a failure to appropriately update rules. The findings are discussed in the context of neurological and pharmacological abnormalities in the conditions that may disrupt prediction error signalling in schizophrenia.
(Received June 21 2010)
(Revised November 18 2010)
(Accepted November 22 2010)
(Online publication January 07 2011)
c1 Address for correspondence: V. C. Huddy, Ph.D., D.Clin.Psy., Kings College London, Institute of Psychiatry, Department of Psychology, De Crespigny Park, London SE5 8AF, UK. (Email: [email protected])