Effects of experience on stimulus-produced reflex inhibition in the rat.

Notes that acoustic-startle behavior in the rat is inhibited by changes in the auditory and visual environment which immediately precede reflex elicitation. A series of 7 experiments was conducted with 165 male Holtzman albino rats which established that this effect was not present in the naive S unless the preliminary stimulus was a relatively intense noise burst. With visual stimuli and moderate auditory stimuli the requisite condition for the production of reflex inhibition was that the S should have experienced the eliciting stimulus. Exposures to the to-be-inhibitory stimulus or to a conjunction of this stimulus and the eliciting stimulus were not necessary. Once established, the inhibitory effect was not degraded by week-long rest periods nor by "unreinforced" exposures to the inhibitory stimulus. It is conjectured that the experiential effect may reflect some increase in a nonspecific state of alertness or arousal. (PsycINFO Database Record (c) 2010 APA, all rights reserved)