Can an Animal Count?

Abstract

SIR JOHN LUBBOCK, in his interesting paper on animal intelligence (NATURE, vol. xxxiii. pp. 46–7), virtually puts this question with reference to the dog. But the question whether a dog, or any other animal, can count will depend upon what we mean by counting. In the ordinary and correct signification of the term, counting consists in applying conventional signs to objects, events, &c., as when we say “one,” “two,” “three,” to the striking of a clock. Clearly in this sense there is no reason to suppose that any animal can count. But there is another sense in which the term “counting” may be used—i.e. as designating the process of distinguishing, with respect to number, between the relative contents of two or more perceptions. While addressing an audience of 100 individuals a lecturer can immediately perceive that it does not contain 1000; and even without, in the true sense, counting them may make a tolerably close guess at their number. The accuracy of such a guess will depend upon two conditions. The first of these is the number of units to be computed, and the second is the previous practice he may have had in that kind of computation. Thus, every man is able to tell the difference between one and two, two and three, &c., up to perhaps seven and eight objects or events, without resorting to the expedient of marking off each with a separate sign. But somewhere about this point most persons require to adopt a system of numerical notation, if they desire to be accurate; and probably no one, without either special practice or some such system, could be perfectly sure whether he held eleven or twelve shillings in his hand, or whether a clock had just struck eleven or twelve. Indeed, it is just because of the rapidly-increasing difficulty of thus computing diminishing differences of ratio by immediate perception, that primitive man first lays the foundations of arithmetic by marking off the objects or events upon his fingers and toes. As already indicated, however, special practice makes a great difference in the accuracy with which such instantaneous computation can be made. Several years ago Prof. Preyer, of Jena, tried some experiments upon this subject, and found, if I remember correctly, that after a course of special training one might acquire the power of instantaneously distinguishing between twenty and twenty-one dots promiscuously scattered over a piece of paper.