Acoustic startle and anticipatory anxiety in humans: effects of monaural right and left ear stimulation

The startle reflex elicited by binaural acoustic startle stimuli is potentiated by the threat of electric shock. The present study explored the lateralization of this fear-potentiated startle reflex effect using acoustic startle stimuli delivered binaurally or monaurally to the left or right ear and recorded from the left and right orbicularis oculi muscles. Consistent with previous results, the acoustic startle to binaural stimulation was potentiated during the anticipation of shock. This effect was also present for monaural stimulation but was greater when startle stimuli were delivered to the right than to the left ear. The results are discussed in terms of hemispheric lateralization during shock anticipation.