Modification of the Effort Expenditure for Rewards Task (EEfRT) for Motivation Studies in Schizophrenia Patients

Abstract

Recent evidence indicates a decrease in willingness to exert effort for rewards in patients with schizophrenia. The exact mechanism of this deficit is unknown, which necessitates further research of the issue using adequate experimental procedures to measure willingness to exert efforts. Among the latter, the most widely used paradigm is the Effort Expenditure for Rewards Task (EEfRT). However, the original version of the task cannot be used in all populations because of socio-economic differences between countries. The present study was aimed to adapt the EEfRT for use in the Russian population. We shortened the task and selected levels of rewards enabling the assessment of patterns of effort expenditure in patients and healthy people. To test the psychodiagnostic properties of the modified version, it was administered to 20 young people (including 15 women) with schizophrenia and 20 healthy controls matched to the patients on demographic characteristics. In addition, we assessed clinical symptoms with the Positive and Negative Syndrome Scale (PANSS) in patients and evaluated schizotypal traits with SPQ-74 in healthy controls. The modified version of EEfRT successfully revealed the normal patterns of effort expenditure for a monetary reward. A decrease in willingness to exert effort and an attenuation of moderating effects of reward magnitude and probability in young patients with schizophrenia were demonstrated. The task therefore allows study those motivational deficits in psychiatric patients, which cannot be assessed with clinical psychometric tools.

Keywords

• motivation
• experimental method
• schizophrenia
• schizotypy
• negative symptoms