negative reinforcement

reaction of placing and then removing all discomfort as a method of encouraging the continuation of the desired behavior

In operant conditioning, reinforcement is an increase in the strength of a response following the presentation of a stimulus contingent on that response. Response strength can be assessed by measures such as the frequency with which the response is made (for example, a pigeon may increase the rate at which it pecks a key), or the speed with which it is made (for example, a rat may run a maze faster). The stimulus contingent on a response is called a reinforcer. Reinforcement can only be confirmed retrospectively, as objects, items, food or other potential 'reinforcers' can only be called such by demonstrating increases in behavior after their administration. It is the strength of the response that is reinforced, not the organism.
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Negative /neg·a·tive/ 1. having a value less than zero. 2. indicating absence, as of a condition or organism. 3. [more]Negative reinforcement - Community and Resources