Page:American Journal of Psychology Volume 21.djvu/16

6 kind of imitation come very readily to mind. One bird starts to fly and the rest follow, one chick drinks and others do so at once.

The problem, then, of the present study is as follows: Can we by experiment and observation demonstrate that in these favorable subjects, the birds, facts are to be found which unmistakably point to imitation of a higher kind than the merely instinctive or the following instinct?

The purpose of the experiments with which we are here concerned may be said to be twofold. First, to obtain a measure of the rate of learning in as many different species of birds as possible. Secondly, to determine if and just how birds of the same and different species imitate each other.

One would naturally expect that conditions favoring imitation might very well interfere with a uniform rate of learning, and vice versa. If two birds fight or pay attention to each other, then neither can at the same time be working to open a box by pulling strings. Nevertheless the writer regards the second aim as more important than the first. At least the present study has been made from this point of view. Results on rate of learning in birds have already been obtained in sufficient number to make later ones chiefly corroborative in value.

The method throughout has been to place on the floor of the large cage in which the birds were confined a small box to be opened. The results in series A, B, and D were obtained in an in-door cage twelve feet long six feet wide and six feet high. The top and one side were covered with white muslin. The other side was formed by the wall of the room in which there were two large windows. The two ends were of wire mesh. The floor, the window sills (the floor being on a level with these), and posts were covered with white paper in order that as much light as possible might be had for taking photographs. All photographs taken in in-door cages have been taken with the camera concealed in an inverted box placed on the floor of the large cage. This box being left in the cage all the time, the birds were quite accustomed to it. It was found that for most days in midwinter with a rapid lens and plate very satisfactory results could be obtained in 0.02-0.01 sec.

Extreme hunger has been carefully avoided. The small box most used was the same as that used with the Cowbirds and Pigeons the description of which may be found on p. 257, volume XVIII of the ''Amer. Jour. Psy.'' This box is twenty inches long thirteen inches wide and twelve high. From Fig. 1 it may be seen that the door is placed in the middle of the front on which last and the left end is a wire mesh covering.