Persistent neophobic behaviour in monkeys: A habit or a trait?

Studies on the effects of rearing conditions on behavioural development showed that most monkeys reared with surrogate mothers persistently avoided a big novel object (paper bag) whereas most monkeys reared by natural mothers would approach it. Conditioned fear and conditioned avoidance, observational learning, and lack of support by the mothers' presence could be excluded as possible causes; we established that the high incidence of phobic behaviour in surrogate-reared groups was caused by deprivation of maternal care. Results of further studies showed that the avoidance was not restricted to the object the Ss had been exposed to in infancy; monkeys still avoiding the bag at 2 years also avoided other big novel objects. Some researchers have found differences in the neurobiological status between surrogate-reared monkeys and mother-reared monkeys. However, the results of our experiments showed that both types of rearing condition produced avoiders as well as non-avoiders. The question under discussion here is whether avoidance of novelty is a habit or a trait. The relative importance of features of surrogates versus real mothers, characteristics of infants and differences in mothering style is discussed.