When Will We Meet Again? Regularities of Social Connectivity and Their Reflections in Memory and Decision Making

Do we move through our social world in lawful ways? And how to describe the regularities that underlie the frequency with which we encounter the different members of our social networks? Based on records of daily social contact, this chapter shows that the probability of contact with another person follows three lawful regularities. Specifically, the probability of future contact is lawfully related to the frequency of past contact, the recency of the last contact and how the past contacts have been distributed over time. The dynamics between the probability of future contact and these aspects of past contact thus seem to follow general regularities that have also been found for word occurrence and document access. Moreover, the distribution of contact probability across the different network members is highly skewed, with frequent contact restricted to only very few individuals. The chapter discusses the possible implications of these regularities for the emergence of cooperation and point out that in an environment in which contact probability to most network members is very low, prominent cooperation heuristics such as tit-for-tat are unlikely to emerge. Moreover, the chapter discusses how memory might assist in assessing the probability of future contact. Specifically, the chapter shows that one plausible mechanism, based on memory activation, will lead to predictable errors in the estimations.