Answer:
It was proposed by Leon Festinger. It states that tension occurs when we become aware of our contradicting attitudes and behaviors. For example, an individual strongly believes that smoking is harmful and highly unrecommended, however, he goes out of his way and decides to smoke anyway. There is an existing conflict between the attitude that smoking is not advised to the action of smoking. We strive to be in psychological harmony but when we are not, we often adjust our attitudes, behaviors, or both. The key is to be in complete harmony.