Endocrinological Responses to a New Interactive HMI for a Straddle-type Vehicle: A Pilot Study

This paper hypothesized that a straddle-type vehicle (e.g., a motorcycle) would be a suitable platform for haptic human-machine interactions that elicits affective responses or positive modulations of human emotion. Based on this idea, a new human-machine interface (HMI) for a straddle-type vehicle was proposed for haptically interacting with a rider, together with other visual (design), tactile (texture and heat), and auditory features (sound). We investigated endocrine changes after playing a riding simulator with either new interactive HMI or typical HMI. The results showed, in comparison with the typical HMI, a significant decrease of salivary cortisol level was found after riding the interactive HMI. Salivary testosterone also tended to be reduced after riding the interactive HMI, with significant reduce in salivary DHEA. The results demonstrated that haptic interaction from a vehicle, as we hypothesized, can endocrinologically influence a rider and then may mitigate rider's stress and aggression.