REACTIONS OF CHICKS TO VISUAL CHANGES DURING FIRST 10 DAYS AFTER HATCHING

The reactions shown by young chicks to environmental changes were estimated by comparing their behaviour whilst undisturbed with that after the change. The observer was not a part of the rearing or testing conditions. After a brief, general reaction to any change, naive 2-, 6- and 10-day-old chicks showed a greater, more prolonged reaction to an increase in illumination, especially if due to a torch-bulb, than to a decrease. The magnitude and duration of chicks' reactions to torch-bulb illumination increased from 1 1 2 to 1 1 2 days, particularly during the first 2 to 3 days. It is assumed that animals gradually learn the characteristics of their environment and that the results of this learning, which might collectively be called an environmental model, form the basis for comparisons made when the environment changes. The reaction to a change is greater if the model has had longer to become established. © 1969.