there are quite a lot of approaches in social network theory that link social cognitive theory such as (neo-)behaviorism to the usage of social networks. I think that the concept of social capital i.e. is one approach that tries to explain how social relations are used by individuals for individual ends (see James S. Coleman, Nan Lin, Ronald Burt, a.o.). I have also published an article on how a concept linked to learning theory (triadic role patterns) might be used in order to explain how actor dispose over their social network (Measuring the Social Capital of Brokerage Roles; in: Connections).
I agree with Volker that there are quite some approaches that connect cognition and social network theories. More recently studies also move into considering pasion or emotions and social network theory, as well as the role of the cognitive mapping of the social network on social network behavior. I can send you a work-in-progress paper (privately) if you are interested in this.