Task and stimulation paradigm effects in a P300 brain computer interface exploitable in a Virtual Environment: A pilot study

The aim of the present study is to compare different visual elicitation paradigms exploitable in a Virtual Environment in order to establish whether the BCI is affected by the structure of the elicitation paradigm, the modalities of stimulus presentation, and the complexity of stimulus recognition and semantic processing. We have developed a device which can control the motion of a cursor on a computer graphical interface, using ERPs (Piccione et al., 2006). Subsequently, we tested different visual elicitation paradigms which evoked P300 waves to control the movement of an object in a virtual environment. Visual stimuli, consisting of four arrows (forward, right, back, left), were randomly presented in peripheral positions of a virtual environment. Users were instructed to recognize only the stimulus related to the preferred object movement direction (target). The sum of the absolute differences between target and non-target traces (ra index) was compared in the different elicitation paradigms. Results showed a significant reduction of ra index with the use of more semantically complex paradigms. Therefore, the P300 BCI system seems to be affected by the structure of the elicitation paradigm, the modalities of stimulus presentation, and the complexity of stimulus recognition and semantic processing.