Tendencies toward triadic closure: Field-experimental evidence

Oregon Convention Center 

Empirical social networks are characterized by a high degree of triadic closure (i.e. transitivity, clustering), whereby network neighbors of the same individual are also likely to be directly connected. It is unknown to what degree this results from dispositions to form such relationships (i.e. to close open triangles) per se or whether it reflects other processes, such as homophily and more opportunities for exposure. These are difficult to disentangle in many settings, but in social media not only can they be decomposed, but platforms frequently make decisions that can depend on these distinct processes. Here, using a field experiment on Twitter, we randomize the existing network structure that a user faces when followed by a target account that we control, and we examine whether they reciprocate this tie formation. Being randomly assigned to have an existing tie to an account that follows the target user increases tie formation by 35%. Through the use of multiple control conditions in which the relevant tie is absent (never existent or removed), we attribute this effect to small variation in the stimulus that indicates the presence (or absence) of a potential mutual follower.