There are two types of reinforcement: positive and negative. “A positive reinforcer is a stimulus added to the environment that results in an increase in the previous response” (Feldman, 2010, p. 178). This is a proven method for contributing to change. A negative reinforcer is also an excellent method of contributing to change and is defined as “an unpleasant stimulus whose removal results in an increase…that a previous response will be repeated in the future” (Feldman, 2010, p. 178). Both of these can be used positively in many situations; however, in the case of negativity, positive reinforcement would be preferable because they are receiving a beneficial stimulus to encourage behavior rather than having something taken from them to instill negative behavior.