In operant conditioning, a form of negative reinforcement in which an organism avoids an aversive stimulus by making a particular response. Typically, a rat is placed in a long, narrow alleyway with a grid floor that becomes electrified and delivers a shock a few seconds after the presentation of a conditioned stimulus such as a light, and the rat can avoid the painful stimulation by running to the end of the alley and stepping into a non-electrified goal box in the time interval between the signal and the shock. In active avoidance conditioning the organism has to make a positive response in order to avoid the aversive stimulus, whereas in passive avoidance conditioning it has to abstain from making the response in order to avoid the aversive stimulus. Also called avoidance learning. See also Kamin effect, Sidman avoidance conditioning, two-way avoidance conditioning. Compare escape conditioning.