Effects of Pairing of Chicks During the Imprinting Period on Filial Responses to an Imprinting Stimulus

Abstract

Most of the previous investigations on imprinting have evaluated the response to the imprinting stimulus in brids who were housed and examined in isolation. It has been generally assumed in these studies that when neonates are given social experience, they imprint on one another, and consequently, are less likely to respond to the imprinting object.In order to evaluate this assumption, numerous investigations have examined the effects of social experience with siblings on imprinting. It is difficult to compare the results of these studies, since they differ in species of subjects, method, or the response indice which they employed. There are, however, two types of conclusions. One of them is that social experience with siblings interferes with imprinted attachment to a maternal surrogate (4, 5, 6, 7, 8,' 12, 15, 24, 28, 29). In contrast, the other is that social experience facilitates imprinting (1, 2, 20, 21, 25).Furthermore, some studies report that imprinting was inhibited by social experience when subjects remained to be with siblings but was facilitated when subjects were briefly isolated after social experience (3,7,11,27). Moreover, there are some studies which report the interaction between the developmental process of subjects and the effects of social experience on imprinting (13, 14, 16). Thus we have no consistent conclusion about the effects of social experience with siblings on imprinting.Therefore, we have no clear reason to say that we must include the training and testing of the subject in isolation. Nevertheless, most studies of imprinting have employd the training and testing in which subjects were in isolation. In particular, when we consider the natural settings in which imprinting occurs, this method in isolation is divergent from the natural setting.