Selection of social partners as a function of peer contact during rearing

Three groups of monkeys were raised with different degrees of contact with their peers. The first group was allowed no contact, the second only visual and auditory contact, and the third was allowed complete and normal contact with their peers. Animals of all three groups were allowed to interact socially; they were then tested for their preference for monkeys raised under the same conditions or for monkeys raised under different conditions. Monkeys raised under the same conditions preferred each other, even if the stimulus animals were completely strange to the test monkey.