EFFECTS OF AGE AND EXPERIENCE ON THE ESTABLISHMENT OF INTERNAL INHIBITION IN FINCHES

An experiment was carried out to test the hypothesis that internal inhibition, learning not to respond in an un‐reinforced situation, is more stable in adult than in young birds and also more stable in birds reared under more varied conditions than in those reared under restricted conditions. Canaries and greenfinches were given the task of differentiating between a dish containing food and covered with a white lid, and an empty dish covered with a black lid. In the earlier negative trials, juvenile canaries were superior to adults in their capacity to ignore the black lid, and juvenile hand‐reared greenfinches were superior to adult wild greenfinches; but in the later trials the two adult groups were superior to these two juvenile groups. A group of juvenile greenfinches reared in an outdoor aviary were superior to all other groups. These results are discussed and it is suggested that a more detailed hypothesis may be formulated: that internal inhibition is weak in very young birds, develops as a result of age and also as a result of experience during the juvenile stage and, later again, weakens slightly.