Effect of Display Response Time on Brain Activity in Human–Machine Interface Commander Operation

With the recent diversification of operating devices, the demand for input operations that require confirmation of the effect of differences in display response on operability has increased. Regarding display response, previous studies have investigated the threshold time and sense of agency for a delayed response during device operation. However, these studies only focused on subjective evaluations. Therefore, this study aims to clarify the human motor characteristics and activated brain regions based on the differences in display response time during device operation. The target motion is the rotational operation of the cylindrical rotary controller using the index finger and thumb. The experimental conditions involve four types of display response times (the duration from the operation to the indicated response). We measured the brain activity using near-infrared spectroscopy, the muscle activity from a surface myoelectric potential measurement device, and the force data of the index finger and thumb tip obtained from two independent six-axis force/torque sensors. Although the experimental results showed no significant difference in the muscle activity and gripping force, a significant difference was observed in the brain activity and the questionnaire survey by the difference in display response time. This investigation reveals that the difference in display response time affects brain activity and subjective information, clarifying the relationship between brain activity and subjective information.