Effects of Primary Imprinting on the Subsequent Development of Secondary Filial Attachments in the Chick

This study reinvestigates the effects of primary imprinting of chicks with either a naturalistic stimulus or an artificial object on subsequent imprinting with artificial objects. Initial experience with a live chick (group C) or a yellow cylinder (group Y) had differential effects on the development of a secondary filial attachment in chicks. In chicks of both groups, growth of attachment to the novel imprinting object manifested itself rather abruptly, but the change in response to the novel object occurred later in C- than in Y-chicks. There was no difference between the groups in the outcome of secondary imprinting: chicks in groups C and Y eventually became equally strongly attached to their novel imprinting stimulus, and when exposed to a third object, chicks in both groups imprinted equally well on this object. Thus, (1) initial imprinting on a naturalistic stimulus postponed, but did not block secondary imprinting on an artificial object, and (2) within the lengths of exposure used, the capacity to form new filial attachments was not limited, contrary to the prediction of the competitive exclusion model for imprinting.Secondary imprinting was delayed for a longer time when chicks were exposed to the novel imprinting stimulus in an unfamiliar environment. This indicates that induction of fear in chicks interfered with the occurrence of secondary imprinting. This effect may have contributed to the difference between groups C and Y in the length of delay of secondary imprinting. Possibly, separation from the first stimulus and exposure to the second stimulus was more fearful to C-chicks than to Y-chicks.