knee-jerk response

• reflexInvoluntary stimulus response
• automaticOperating without intervention
• instinctiveArising without conscious thought
• gutDigestive tract, or instinct
• reactionResponse to stimulus

snap · impulse · kneecap · hammer · twitch · flinch · unthinking · visceral · immediate · defensive · trigger · stimulus · involuntary · spontaneous · recoil · conditioned · Pavlovian · thoughtless

• reflex trainingreaction time, quick reflexes, stimulus-response, reflex arc, speed drills