Volume 82, Number 2, April 2008
Article Number 28002
Number of page(s) 5
Section Interdisciplinary Physics and Related Areas of Science and Technology
Published online 26 March 2008
EPL, 82 (2008) 28002
DOI: 10.1209/0295-5075/82/28002

Role of activity in human dynamics

T. Zhou1, 2, H. A. T. Kiet3, B. J. Kim3, B.-H. Wang1 and P. Holme4

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

received 24 December 2007; accepted in final form 19 February 2008; published April 2008
published online 26 March 2008

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.

87.23.Ge - Dynamics of social systems.
89.65.-s - Social and economic systems.
89.75.Da - Systems obeying scaling laws.

© EPLA 2008