H. Tajfel and J. C. Turner, “The Social Identity Theory of Intergroup Behaviour,” in Psychology of Intergroup Relations, ed. S. Worchel and W. G. Austin (Chicago IL: Nelson-Hall, 1986), pp. 7–24; E. A. Losin et al., “Own-Gender Imitation Activates the Brain’s Reward Circuitry,” SCAN 7 (2012): 804; R. Yu and S. Sun, “To Conform or Not to Conform: Spontaneous Conformity Diminishes the Sensitivity to Monetary Outcomes,” PLoS ONE 28 (2013): e64530.