I. Introduction
NEW types of visual stimulation may cause adverse effects on humans [1]–[5]. In the previous works, the authors have reported that the maximum cross-correlation coefficient between heart rate and blood pressure variabilities, , reflects the change in the autonomic nervous activity caused by exposure to visual stimulation which may cause motion sickness [6] [7]. The mechanism of the change in is considered as follows; In the case of a healthy human who does not receive any stimulation, his heart rate is changed by the baroreflex function in response to the change in blood pressure, and then the correlation between these variables is high and roughly constant. On the other hand, if he is affected by some kind of stimulation and his physiological and/or psychological condition changes, the effects will change the activity of the autonomic nervous system and the baroreflex function, then the correlation will decrease. Therefore is considered as an index reflecting the baroreflex function.