1983 年 1 巻 p. 11-18
Effects of the physical properties of reflex-evoking sounds upon the magnitude of blinks and the subjective estimation of startle were examined. The electromyographic activity of orbicularis oculi was measured with eyes closed during wakefulness. Twenty young adults were assigned into one of following four experiments. In each experiment, the standard sound stimuli (noise in Exp. 1-3 and 1000 Hz tone in Exp. 4) were 100 dB, 50ms and less than 1 ms in their intensity, duration, and rise/fall time respectively. In Exp. 1, intensity was varied from 80 to 90,100,110, and 120dB. In Exp. 2, duration was varied from 10 to 30, 50, 70, and 90ms. In Exp. 3 and 4, r/f time was varied from 0 to 6, 12, 18, and 24ms. Results showed that the amplitude of the reflex increased linearly as functions of the noise intensity and the duration, but it decreased as a function of the r/f time. Subjective estimation for the magnitude of startles behaved alike to the reflex amplitude. The positive correlations between these two measures were significant in 17 out of 20 subjects. It is, therefore, concluded that the auditory evoked eyeblinks recorded by an EMG of orbicularis oculi are significant indexes of the startles in humans.