Tests of a principle of reflex modification: Modification of the human eyeblink-reflex is independent of the intensity of the reflex-eliciting stimulus

The human airpuff-elicited reflexive eyeblink, like the startle reflex of rats and pigeons, occurs with either reduced amplitude or latency when a brief auditory stimulus precedes the reflex-eliciting event by an appropriate lead interval. In common with the overt startle reflex of lower animals, the degree of inhibition or latency reduction of an airpuff-elicited eyeblink in human adults proved to be independent of the intensity of the eyeblink-eliciting airpuff. This finding supports the principle that the amount of a given reflex modification effect (whether latency or amplitude reduction) is determined by the parameters and lead time of the modifying stimulus and not by those of the reflex-eliciting event.