In general, it is difficult to compare biological reactions to some kind of stimulation among subjects on the basis of a single physiological parameter such as heart rate variability because there is a large individual variability in its values. A solution to this problem is to utilize the correlation between physiological parameters. In previous works, the maximum cross-correlation coefficient between heart rate and blood pressure variabilities changed when subjects were strongly affected by visual stimulation. In the present work, this index was compared with a traditional one associated with the arterial baroreflex gain to investigate the mechanism of the change in the index. Resting heart rate and continuous blood pressure of twenty-eight healthy adults were measured for five minutes and analyzed. The results showed that these two indices changed similarly to each other while there was little correlation in the mean value between them. Furthermore, the lag time from blood pressure variability to heart rate variability was inversely correlated with the traditional index.