Outgroup threat and the emergence of cohesive groups: a cross-cultural examination by Lang, M, Xygalatas, D, Kavanagh, C, Boccardi, N, Halberstadt, J, Jackson, C, Martínez, M, Reddish, P, Tong, EMW, Vazquez, A, Whitehouse, H, Yamamoto, ME, Yuki, M, Gomez, A