Secondary imprinting in the domestic chick blocked by previous exposure to a live hen

Two experiments were carried out to investigate secondary imprinting in the domestic chick, Gallus gallus. Experiment 1 established that, after chicks with very limited prior visual experience had been exposed to a moving cup during the first 3 days of life, the cup when stationary would suppress distress calling. The main experiment, experiment 2, then examined the effects of various forms of prior experience on the development of this kind of imprinting. Three groups of chicks were exposed on days 1 and 2 to either a live hen (Hen group), a moving object (Windmill group) or the same object when stationary (Control group). On days 4, 5 and 6 all subjects were given training of the kind used in experiment 1; imprinting to the cup was obtained in the Windmill and Control groups, but not in the Hen group. On days 11 and 12 retention tests were given; these showed good retention of primary imprinting, in that the cup was still effective in suppressing distress calling in the Control group and likewise the windmill in the Windmill group, but no effect of secondary imprinting was detected, in that the cup no longer affected the behaviour of the chicks in the Windmill group. These results indicated that primary imprinting with certain stimuli, as in the Hen group, can subsequently exert powerful interference with secondary imprinting and they supported a previous claim that, where secondary imprinting does occur, it is relatively unstable.