Prepulse inhibition

Prepulse inhibition: preceding stimulus attenuates the startle response.

Prepulse Inhibition (PPI) is a neurological phenomenon in which a weaker prestimulus (prepulse) inhibits the reaction of an organism to a subsequent strong startling stimulus (pulse). The stimuli are usually acoustic, but tactile stimuli (e.g. via air puffs onto the skin) and light stimuli are also used.