Dresden 2009 – scientific programme

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AGSOE: Arbeitsgruppe Physik sozio-ökonomischer Systeme

AGSOE 17: Networks: From Topology to Dynamics II

AGSOE 17.2: Talk

Thursday, March 26, 2009, 10:45–11:15, BAR 205

About human activity, long-term memory, and Gibrat's law — •Diego Rybski¹, Sergey V. Buldyrev², Shlomo Havlin³, Fredrik Liljeros⁴, and Hernan A. Makse¹ — ¹Levich Institute and Physics Department, City College of New York, New York, NY 10031, USA — ²Department of Physics, Yeshiva University, New York, NY 10033, USA — ³Department of Physics, Bar-Ilan University, Ramat-Gan 52900, Israel — ⁴Department of Sociology, Stockholm University, S-10691 Stockholm, Sweden

A central research question in the social sciences for several centuries has been whether any law like patterns in the unintended outcomes of human action exist. Here we investigate the existence of scaling laws in the human activity of communication, considering the number of messages sent by individuals as a growth process in time. We analyze millions of messages sent in two social online communities and uncover power-law relations between fluctuations in the growth rate and the activity of the members. We attribute this scaling law to a long-term persistence of human activity beyond daily or weekly cycles holding up to more than a year. Based on such an underlying long-term correlated dynamics, we elaborate a consistent framework for the empirical evidences, establishing a missing link between the scaling behavior in the growth and long-term persistence. Our results indicate that large fluctuations in communication activity can be expected as an unintended consequence of human interaction. This finding is of importance for both designing communication systems and for understanding the dynamics of social systems.