We like individuals who are similar to us (Burger et al, 2004) and we are more likely to comply those individuals who we like (Cialdini, 2009). Consequently, we are more easily persuaded by those who are similar to ourselves. Sales people can use this similarity effect to increase their sales by appearing similar to their customers even when they are not actually alike.
Incidental similarity is where two individuals appears similar in a trivial way such as a shared birthday, birth place or initials. Research has shown that we are more easily persuaded by someone who shares these trivial characteristics even those they do not mean the person shares similar attitudes, values or opinions to ourselves (Miller, Downs, and Prentice, 1998).
Jiang, Hoegg, Dahl and Chattopadhyay (2010) investigated the effects of incidental similarity on the relationship between a sales person and a customer. They hypothesised that the consumer will like the sales person more if they share the same birthday and that this likeability will lead to increased sales. They also hypothesised that the level of social connectedness the consumer feel with the sales person will influence how persuasive incidental similarity can be.
In pairs, participants were given the biography of a personal trainer to read which included the birth date of the trainer. This birth date was the same as one of the participants in the pair. The pair were then given a 10 minute sales pitch about the personal trainer program and asked to answere a questionnaire measuring their attitudes towards the trainer and program, their purchase intentions and how connected they felt towards the personal trainer. The results showed that the participants who shared their birthday with trainer were significantly more likely to say they would sign up to the programme, had higher feelings of connectedness with the trainer and had a more positive attitude towards the trainer than the participants who did not share the same birthday.
In a second study the same procedure was used with the personal trainer set up except that the researchers also measured the participant’s individual levels of self-esteem and social connectedness. The aim of this follow-up study was to see whether individual differences in the levels of social connectedness and self-esteem influenced the relationship between incidental similarity and persuasion. The results showed that those with lower social connectedness scores were less influenced by incidental similarity to the personal trainer than those with higher social connectedness scores. However they did not find any effect of self-esteem on the relationship between incidental similarity and persuasion. This study shows that those of us who with a higher quality and quantity of social interactions (high social connectedness) are more likely to be influenced and persuaded by incidental similarity.
The graphs below show the effect incidental similarity has on attitudes and purchase intentions for participants with an average, high and low social connectedness scores. Those with a high social connectedness score are more influenced by incidental similarity (higher purchase intention and more positive attitudes towards trainer) than those with low social connectedness scores.
By Anna Caswell
Burger, J. M., Messian, N., Patel, S., del Prado, A., & Anderson, C. (2004). What a coincidence! The effects of incidental similarity on compliance. Personality and Social Psychology Bulletin, 30, 35-43.
Cialdini, R. B. (2009). Influence: Science and Practice (5th ed.). Boston: Allyn & Bacon.
Jiang, L., Hoegg, J., Dahl, D.W., & Chattopadhyay, A. (2010). The Persuasive Role of Incidental Similarity on Attitudes and Purchase Intentions in a Sales Context. Journal of consumer research, 36, 778- 791.
Miller, D. T., Downs, J. S., & Prentice, D. A. (1998). Minimal conditions for the creation of a unit relationship: The social bond between birthday mates. European Journal of Social Psychology, 28, 475-81.