1) Removing an aversive stimulus as a consequence of a response resulting in the maintenance of or an increase in rate of the behavior. A behaviour has been negatively reinforced if it increases or is maintained as a function of the contingent removal or reduction of a stimulus. This procedure sometimes is referred to as escape conditioning.

2) The reinforcement from the termination of an aversive Stimulus. For example, the termination of a baby's crying negatively reinforces a mother for picking the child up.

3) When an operant response results in the removal or avoidance of an aversive event, the contingency is called negative reinforcement. If the response is made in the presence of the aversive stimulus, it is an escape response. When the operant prevents the aversive stimulus, it is an avoidance response. In both cases, the removal or prevention of an aversive event strengthens operant behavior.