§ 3. Comparison. — "The growing mind, we may suppose, passes beyond simple perception when some striking difference in what is at the moment perceived is the occasion of a conflict of presentations. The stalking hunter is not instantly recognised as the destroying biped, because he crawls on all fours : or the scarecrow looks like him, and yet not like him, for, though it stands on two legs, it never moves. There is no immediate assimilation ; percept and idea remain distinct till, on being severally attended to and compared, what is there is known in spite of the differences."*

* Ward, Article "Psychology" in Encyclopaedia Britannica, ninth edition, xx., p. 78. Ibid.

Such a comparison is a complex process, involving a series of judgments, such as — "It crawls ; It does not move ; and the like." There are abundant occasions in animal life which might usefully call into play mental operations of this kind. Whenever things are in appearance different, although they are for practical purposes the same, or whenever they are in appearance similar, although for practical purposes they differ, a problem arises which would be most effectively solved by deliberate comparison. By deliberate comparison I mean a mental confronting of the two objects, and a transition of attention from the one to the other, so as to discover some respect in which similar things differ in spite of their similarity, or in which different things agree in spite of their diversity, and also a fixing of the precise nature of this agreement or difference. If an unpalatable moth resembles in its markings a palatable moth, a bird will be apt to confuse them, and so meet with disagreeable disappointment. The bird might conceivably attempt to overcome the difficulty by setting a specimen of the disagreeable species side by side with one of the agreeable species, and then, examining them alternately, might consider first one character and then another of each, so as to find out distinguishing differences. Or again, without bringing the two actual objects together, it might examine the one as perceived and the other as ideally represented, and go through the same process. This would be much harder because it would require a strong and persistent effort of ideational thinking to keep before the mind a sufficiently accurate image of the absent object. Now the supposed case of the bird actually confronting the two objects, alternately scrutinising each, and passing in turn from one characteristic to another, has a strong air of improbability. As a matter of fact, we never observe animals behaving in such a manner as to make this interpretation of their actions necessary or even probable. But if they do not compare two objects when both are perceived, it is a fortiori unlikely that they should do so when one has to be ideally recalled, for, as we have said, this is the harder task. In fact, we have good reason to reaffirm Locke's dictum that "brutes compare but imperfectly." "It seems to me," he says, "to be the prerogative of human understanding, . . . when it has sufficiently distinguished any idea, ... to cast about and consider in what circumstances they are capable to be compared."*

* Locke's Essay concerning Human Understanding (Eraser), vol. i., pp. 204205.

We have seen that systematic observation of animals confirms this view.* It is the one result most distinctly brought out in Mr. Lloyd Morgan's book on Comparative Psychology. I may here quote an experiment which he carried out with great care and patience. Taking with him a dog which had been trained to fetch and carry, he threw a stick into a field surrounded by railings. The dog bounded after the stick, and brought it back in his mouth as far as the railings. But here he was confronted with a difficulty; he could get through himself, but he could not get the stick through. His experience had not taught him that the only way of succeeding was by grasping the end of the stick; instead of this, he tugged now here, now there, in a perfectly uncritical way. If, by accident, he did get hold of the right end of the stick, or if Mr. Morgan showed him how to proceed, this seemed to yield him no assistance on the repetition of the experiment. He had stumbled on the solution, but could not do the trick again. This was no casual observation; it was a systematic experiment repeated day after day, and only one of a course of similar experiments. It is evident that the dog here passed from one alternative to another without selective comparison; so that when he hit on the right one or was shown it, he failed to note the points in which it differed from unsuccessful attempts.

* Cf. the account of Mr. Thorndike's experiments, bk. iii., div. i., ch. i., § 6.