r6.
Michael Argyle (1991), Cooperation, pp 16–17; David W. Johnson and Frank P. Johnson (1975), Joining Together: Group Theory and Group Skills. Both Argyle and the Johnson brothers cite Morton Deutsch’s classic 1940s experiments, which compared cooperative groups with competitive ones (i.e., groups whose task was designed for cooperation versus groups where success depended on individual performance either relative to, or independently of, other members in the group). See George C. Homans (1951), The Human Group, p 111.