2008 Volume 44 Issue 11 Pages 871-877
Influence of sound pressure level of beep stimulation was quantitatively analyzed and discussed for8subjects in terms of ability for raising vigilance level and for keeping the subjects awake. An acceleration characteristic of saccadic eye movement was used as a vigilance index, and calculated in real time to impose the stimulation of70, 80or90dB when the vigilance index dropped below a predetermined threshold. The results showed following;(1) increasing rate of the vigilance index caused by the90dB stimulation was significantly higher than that by the70dB stimulation,(2) the increasing rate immediately after the simulation was the highest in the90dB condition, however no significance was confirmed among the conditions,(3) although the90dB stimulation showed longest duration of arousal effect, it was not longer than that of the80dB stimulation. Since significant drops of the vigilance index were observed7s (or longer) after the90dB stimulation in two subjects, further investigation seemed necessary for the rebound phenomenon against the90dB beep stimulation.