Liking What Others “Like”: Using Facebook to Identify Determinants of Conformity

In this paper we explore the micro-level determinants of conformity. Members of the social networking service Facebook express positive support to content on the website by clicking a Like button. We set up a natural field experiment to test whether users are more prone to support content if someone else has done so before. To find out to what extent conformity depends on group size and social ties we use three different treatment conditions: (1) one stranger has Liked the content, (2) three strangers have Liked the content, and (3) a friend has Liked the content. The results show that one Like from a single stranger had no impact. However, increasing the size of the influencing group doubled the probability that subjects expressed positive support. Friendship ties were also decisive. People were, on average, four times more likely to press the Like button if a friend, rather than a stranger, had done so before them. The existence of threshold effects in our experiment clearly shows that both group size and social proximity matters when opinions are shaped.