Besides attention there is another topic somewhat apart from our general one, which yet deserves a few words. It concerns animals’ social consciousness, their consciousness of the feelings of their fellows. Do animals, for example, when they see others feeding, feel that the others are feeling pleasure? Do they, when they fight, feel that the other feels pain? So level-headed a thinker as Lloyd Morgan has said that they do, but the conduct of my animals would seem to show that they did not. For it has given us good reason to suppose that they do not possess _any_ stock of isolated ideas, much less any abstracted, inferred, or transferred ideas. These ideas of others’ feelings imply a power to transfer states felt in oneself to another and realize them as there. Now it seems that any ability to thus transfer and realize an idea ought to carry with it an ability to form a transferred association, to imitate. If the animal realizes the mental states of the other animal who before his eyes pulls the string, goes out through the door, and eats fish, he ought to form the association, ‘impulse to pull string, pleasure of eating fish.’ This we saw the animal could not do. In fact, pleasure in another, pain in another, is not a sense-presentation or a representation or feeling of an object of any sort, but rather a ‘meaning,’ a feeling ‘_of the fact that_.’ It can exist only as something thought _about_. It is never ‘a bit of direct experience,’ but an abstraction from our own life referred to that of another. I fancy that these feelings of others’ feelings may be connected pretty closely with imitation, and for that reason may begin to appear in the monkeys. There we have some fair evidence for their presence in the tricks which monkeys play on each other. Such feelings seem the natural explanation of the apparently useless tail-pullings and such like which make up the attractions of the monkey cage. These may, however, be instinctive forms of play-activity or merely examples of the general tendency of the monkeys to fool with everything. INTERACTION I hope it will not be thought impertinent if from the standpoint of this research I add a word about a general psychological problem, the problem of interaction. I have spoken all along of the connection between the situation and a certain impulse and act being stamped in when pleasure results from the act and stamped out when it doesn’t. In this fact, which is undeniable, lies a problem which Lloyd Morgan has frequently emphasized. _How are pleasurable results able to burn in and render predominant the association which led to them?_ This is perhaps the greatest problem of both human and animal psychology. Unfortunately in human psychology it has been all tangled up with the problems of free will, mental activity, voluntary attention, the creation of novel acts, and almost everything else. In our experiments we get the data which give rise to the problem, in a very elementary form.