Responses to novelty in phobic and non-phobic cynomolgus monkeys: the role of subject characteristics and object features.

In two previous studies it has been shown that most surrogate-reared cynomolgus monkeys became phobic of a harmless object (a big paper bag) while most mother-reared monkeys approached that object. Results of the first study seemed to indicate that the phobic reaction was restricted to the bag. Barnett and Cowan (Interdisciplinary Science Review, 1, 43-62, 1976) and Suomi (Anxiety disorder in childhood, pp. 1-23, 1986), however, reported that subjects (respectively rats and monkeys) that avoided a first novel object also avoided subsequent novel objects. In the present study we exposed phobic (bag-avoiding) and non-phobic (bag-approaching) monkeys from the study by Röder, Timmermans and Vossen (Behaviour Research and Therapy, 27, 221-231, 1989) to several big and small novel objects. Our results show that, irrespective of their rearing conditions, subjects that were phobic also avoided big novel objects while subjects that were non-phobic approached big novel objects. The reaction to small novel objects was independent of the previous reaction to the bag.