Physiological measurements on a gaming virtual reality headset using photoplethysmography: A preliminary attempt at incorporating physiological measurement with gaming

Digital games or computer game playing can be considered as a psychological activity. Many psychological studies have been undertaken and numerous hypotheses have been created about game playing, partly to assist with game design. Psychophysiology, a field of psychology and physiology, has also been applied as a tool for game design and game science in the belief that psychophysiological or physiological measurements and their interpretation could be helpful for game development. However, practical problems with measurements arise in attaching sensors to players. In contrast, virtual reality (VR) head-mounted displays for gaming have seen rapid development in recent years and have been commercialized for the general public. These VR display headsets must be fixed on the player's head while playing. We realized that a physiological measurement could be autonomously realized if the sensor device was embedded in the VR headset. Here, we propose a novel concept of physiological measurement that is highly compatible with gaming VR headsets. Our system can collect unconstrained physiological measurements during game playing. As a first attempt of this concept, photoplethysmography (PPG)-arterial pulse measurement using light to derive the heart rate-was embedded in a headset and its heart rate measurement was evaluated. A novel photoplethysmograph embedded in a head-mounted VR headset was designed and realized. Reflectance-type PPG using green light gave stable measurements under several conditions such as alternating light emission from the headset display, blinking by the subject, and breathing change. Heart rate changes during a VR game can thus be measured while wearing VR glasses by using the photoplethysmograph. We expect that embedded physiological measurement using these VR glasses can be utilized for health management in the near future.