Behaviour Change

PROPAGANDA FOR CHANGE is a project created by the students of Behaviour Change (ps359) and Professor Thomas Hills at the Psychology Department of the University of Warwick. This work was supported by funding from Warwick's Institute for Advanced Teaching and Learning.

Thursday, February 20, 2014

Similarity plays a more important role in compliance than we have imagined.

The tactic of similarity works as a type of social proof effect. It means that social proofs works best when the person we are watching is similar to us (Festinger, 1954). It has several underlying psychologic causes: firstly, feeling similar to another person increases attraction to the person. Secondly, similarity and attraction promote resistance-reducing perception(Byrne, 1971). Many researches have been done to look in to this tactic, for example, Aune and Basil (1994) found that donations to charity more than doubled when the requester claimed to be similar to the buyer ‘I’m a student here too'. 

The study I am going to talk about here is an interesting one because was set up on the basis of reactance theory, it means when people think hat their freedom is threatened, there is a strong motivation to resort the threatened freedom by not complying to someone. Reactance theory is a robust one therefore many believe that persuader should avoid threatening persuasion tactics (S.S,Brehm & Brehm, 1981). 

A study by Silvia in 2005 investigated the effect of similarity on increasing compliance and reducing resistance. The experimenter had 62 participants and three groups of communicators differ in the level of similarity in terms of shared birthday, first name, gender and year in school to the participants. The first group was with high similarity with participants, the second group was in low similarity with participants and the third group did not reveal their information to participants. The participants then receive a message by reading an easy that did or did not contain elements that threaten their freedom to hold a different attitude towards. At the end, the participants were asked to rate on a scale of ‘how much do you agree with the author’ to test their compliance. 

The result showed that treating messages reduced agreement relative to normal messages only when similarity was low. Table 1 showed that when the similarity was high, threats to freedom did not create reactance. What is more intriguing is that when threat was high, people still agreed more with the similar communicator than with the dissimilar communicator. It is surprising to see how powerful the similarity tactic is because it could competently counter act the effect of the robust reactance theory.


Aunel, R. Kelly, and Michael D. Basil. "A Relational Obligations Approach to the Foot‐In‐The‐Mouth Effect." Journal of Applied Social Psychology 24.6 (1994): 546-556.

Byrne, D. (1971). The attraction paradigm. New York: Academic.

Festinger, Leon. "A theory of social comparison processes." Human relations7.2 (1954): 117-140.

Snyder, M. L., & Wicklund, R. A. (1976). Prior exercise of freedom and
reactance. Journal of Experimental Social Psychology, 12, 120–130

By Regina Yeung

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