By adopting majority rule within a renormalization group approach, we can show that the strength of inter-group interaction in a social system either grows or shrinks monotonically with increasing gc with group size regardless of the initial strength. Our approach clearly demonstrates that the phenomena of crowd psychology, such as an extreme anti-reaction between different ethnic or ideological groups, could be a consequence of the many-particle nature of social systems when the initial strength of the interaction is larger than a critical value. The effect of neutral opinion holders is critically examined using the spin-one Ising model. The critical size of the population of neutral opinion holders, that can prevent crowd polarization, depends on the block spin rule.
Bibliographical noteFunding Information:
This work was partially supported by the Max Planck Institute for the Physics of Complex Systems through a visiting program (to C.K.K.) and the Ministry of Education, Science and Technology of Korea through the National Research Foundation of Korea (2011-0008074 and 2010-00453) (to K.J.B.L.).
- block spin
- crowd psychology