power of analysis possessed by these and other animals. In the experience of the individual animal, as in human experience, there is a constant recurrence of old situations with a slightly new aspect. Tests of the power of inhibition, of analysis, as well as imitation, the writer is constrained to believe find favorable conditions as much in varied relations of the same apparatus as in refinement and multiplication of new apparatus. The same food box used with most of my birds may seem to the reader an undue adherence to the rules of scientific experimentation, but the results we trust will abundantly justify the method adopted.
The sub-title of the present paper, "A Criterion of Imitation," has reference directly to a point of method rather than that of apparatus. In an earlier paper the writer obtained some results of interest from the standpoint of Imitation when a change was made in the fastening to a box and both English Sparrows (the one accustomed to opening the door in a now impossible way and the other never having opened the box) had opportunity at the same time to do something. The first tried the old method several times in the presence of the second whereupon the second gave some signs of imitation of a rather blind and impulsive kind.
Early in the present work the writer began to make use of a certain standard or criterion of the presence of Imitation which may be stated somewhat as follows: Bird No. i is induced to open a box which may be done in one of several different ways. Bird No. 2 by the means indicated above is allowed to supplant No. i . The effect of this different method of opening on the behavior of No. i is closely observed and recorded. The behavior of No. 2 will rarely be identical repetition. We may be fairly certain, then, that No. i will have furnished to him by No. 2, or vice versa, an example or act to imitate.
Such a criterion has certain obvious advantages. Students of imitation in animals allow No. i only to try to open the box but never to succeed. They then allow it to see from some place of imprisonment, or other rather removed position, No. 2 do the act of opening. No. i is then released to see if he will do as No. 2 did. They by this method almost certainly get less of rivalry, effective interest and attention, or of that condition of the mental which in man is so often the precondition for the performance of the imitative act. This condition is probably most often brought about through the fact that the animal or human has had previous experience with, or similar to, the act to be imitated.
Let us consider briefly a concrete case or two, more of which we shall see later. The Old Crow left at once the end of the food box, to work as the young Crow had just done on the front
