Effects of maternal mobility on the development of rocking and other behaviors in rhesus monkeys: a study with artificial mothers.

Mechanically driven mobile artificial mothers effectively prevented the development of stereotyped body-rocking in rhesus monkeys. Monkeys were maternally separated at birth and assigned to 2 groups. Both groups were placed with surrogates, identical in construction except that for 1 group the surrogate was in motion 50% of the time from 0500 hours to 2400 hours each day, and for the other group the surrogate was stationary. All but 1 of the 10 monkeys raised with stationary artificial mothers developed rocking as an habitual pattern whereas none of the 9 monekys raised with mobile mothers did so. The data also suggest that emotional responsiveness was reduced in monkeys raised with mobile mothers, compared to monkeys raised with stationary devices.