Somatosensory P2 reflects resource allocation in a game task: assessment with an irrelevant probe technique using electrical probe stimuli to shoulders.

The present study investigated whether event-related brain potentials (ERPs) elicited by task irrelevant somatosensory stimuli to the shoulders reflect the amount of processing resources allocated to a game task. In the experiment, electrical stimuli were presented to the right (or left) shoulder with a high probability (80%) and to the other shoulder with a low probability (20%) while participants were performing a driving simulation game. The deviant low-probability stimuli elicited somatosensory P2, and this P2 amplitude decreased when the task was difficult. The results show that the ERPs for somatosensory stimuli to the shoulders can reflect the amount of resources deployed even when the stimuli are ignored. This is a useful method for the evaluation of mental workloads in complex circumstances because it does not interfere with inputs of auditory or visual information or operations using the limbs.