Aversion Therapy is a form of therapy in which the client is given suggestions which focus on and emphasis the negative aspects of habit or behaviour or even introduce negative aspects to a habit or behaviour. The intended result of this type of conditioning is to associate the unwanted habit or behaviour with the negative and unpleasant sensations in order for change to take place. An example of this is the use of causing the smell of cigarette smoke to bring on nausea. This however can backfire if the subject of the aversion therapy walks into a room where someone has previously smoke they would also feel nauseous in that situation too.