While attitudes can have a powerful effect on behavior, they are not set in stone. The same influences that lead to attitude formation can also create attitude change. People can change their attitudes in two ways. First, they can be motivated to listen and think about the message, which can lead to a shift in attitude. Or they might be influenced by characteristics of the speaker, leading to a temporary shift in attitude. Messages that are thought provoking and that appeal to the viewer are more likely to lead to permanent changes in their attitude. As mentioned in the previous post, people can also change their attitudes when they have conflicting beliefs about a topic. In order to reduce the tension created by these incompatible beliefs, people often shift their attitudes. 

Link to Blog: http://dissonancetheory-smk683.blogspot.com/2012/04/dissonance-theory-2.html