Variation in beliefs about aggression as a function of relationship to the opponent

On the basis of evolutionary principles involving the balance of cooperation and competition, it was predicted that aggressive exchanges between close kin would be viewed in more expressive (E) and less instrumental (1) terms, and those between strangers in more I and less E terms. Aggressive exchanges between friends would be intermediate. These predictions were confirmed in a sample of 102 British undergraduates who answered versions of the short Expagg questionnaire, modified for the three different opponents. As in other studies, men showed more I and less E beliefs about their aggression, and these differences were maintained across all three categories of relationship. Women's beliefs about aggression were similar (high E and low 1) for both close kin and friends, a finding which can be related to the greater importance of emotional closeness in women's friendships. The findings demonstrate the context-dependent nature of beliefs about aggression, and are consistent with predictions from evolutionary principles. (C) 2003 Elsevier Ltd. All rights reserved.