Acoustic augmentation and inhibition of the human eyeblink.

The human eyeblink elicited by a mechanically produced tap to the glabella was inhibited by a mild acoustic stimulus presented 200 msec prior to the tap and was augmented when the same acoustic stimulus was presented simultaneously with the tap. Monaural presentation of the acoustic stimulus prior to the tap yielded more reflex inhibition than when that same stimulus was presented binaurally. Binaural presentation of the acoustic stimulus simultaneously with the tap yielded more reflex augmentation than when that same stimulus was presented monaurally. These findings lend credence to the proposition that reflex inhibition and reflex augmentation are mediated by separate neural pathways.