ABSTRACT
It is by now well known that when a mild sensory event, such as a weak tone or a dim light flash, precedes a startle-eliciting signal by an appropriate interval (depending on the circumstances usually between 50 and 200 msec), the amplitude of the elicited reaction can be reduced by as much as 50%. This reflex modification effect is called prepulse inhibition, and it has broad generality. Prepulse inhibition occurs in amphibians ( Yerkes, 1905), birds (Stitt, Hoffman, Marsh, & Schwartz, 1976), and mammals, including man (Hoffman & Ison, 1980). It does not depend on learning. Inhibitory effects are observed the first time that a tone or light flash precedes a startle-eliciting stimulus. Nor does it require the subject’s direct attention. Prepulse inhibition has been assessed while subjects were sleeping (Silverstein & Graham, 1979), while they were reading (Dykman & Ison, 1979), and while they were watching a slide show (Hoffman, Cohen, & Stitt, 1981).
