Role of activity in human dynamics

¹  Department of Modern Physics, University of Science and Technology of China - Anhui, Hefei 230026, PRC
²  Department of Physics, University of Fribourg - CH-1700, Fribourg, Switzerland
³  Department of Physics, BK21 Physics Research Division, and Institute of Basic Science, Sungkyunkwan University Suwon 440-746, Republic of Korea
⁴  Department of Computational Biology, School of Computer Science and Communication, Royal Institute of Technology - 100 44 Stockholm, Sweden, EU

Corresponding author: beomjun@skku.edu

Received: 24 December 2007
Accepted: 19 February 2008

Abstract

The human society is a very complex system; still, there are several non-trivial, general features. One type of them is the presence of power-law–distributed quantities in temporal statistics. In this letter, we focus on the origin of power laws in rating of movies. We present a systematic empirical exploration of the time between two consecutive ratings of movies (the interevent time). At an aggregate level, we find a monotonous relation between the activity of individuals and the power law exponent of the interevent time distribution. At an individual level, we observe a heavy-tailed distribution for each user, as well as a negative correlation between the activity and the width of the distribution. We support these findings by a similar data set from mobile phone text-message communication. Our results demonstrate a significant role of the activity of individuals on the society-level patterns of human behavior. We believe this is a common character in the interest-driven human dynamics, corresponding to (but different from) the universality classes of task-driven dynamics.