Motivation modulates the P300 Amplitude during BCI use
Kleih, S. C.1, Nijboer, F.1, and Kübler, A.1,2
1Institute for Medical Psychology and Behavioural Neurobiology, University of Tübingen; 2Department of Psychology I, Biological Psychology, Clinical Psychology and Psychotherapy, University of Würzburg
Brain-Computer Interfaces (BCI) provide muscle-independent communication for paralyzed patients. Individuals differ in their ability to use a BCI. This study examines the relation between motivation and the P300 amplitude within a BCI controlled by event-related potentials (ERP). In two experimental groups participants received 25 or 50 Cent for each correct letter selection; the control group was not rewarded. Motivation was assessed with a BCI adapted questionnaire and a visual analogue scale. BCI performance was defined as the percentage of correctly selected characters (group mean = 99%). At Cz the P300 amplitude was positively correlated to self-rated motivation (r=.50). Offline analysis revealed that highly motivated participants would have needed fewer trials for a discriminable ERP and thus, would have been able to communicate faster with the ERP-BCI. These results indicate that motivation may contribute to variance in BCI performance and has to be monitored in BCI settings.