Animal intelligence: Experimental studies

by Edward L. Thorndike

In actual present practice, if observers were asked to identify the intensity of John’s toothache on a scale running from zero intensity up, the variability of the reports would be very great in comparison with those of stature or body-temperature. Supposing the most intense toothache to be called K, we might well have reports of from say .300 K to .450 K, some observers identifying the fact with a condition one and a half times as intense as that chosen by others. But such a variability might also occur in primitive men’s judgments of length or temperature.

It is important to note that the accuracy of John’s own identification of it depends in any case on his knowledge of the scale and his power of comparing his toothache therewith. Well-trained outside observers might identify the intensity of John’s toothache more accurately than he could.

In the case of John’s anxiety, the most striking fact is the low degree of accuracy in identification. The quality of the anxiety and its intensity would both be so crudely measured by present means that even if the observers were from the score of most competent psychologists, their reports would probably be not much better than, say, the descriptions now found in masterpieces of fiction and drama. Science could not tell at all closely how much John’s anxiety at this particular time resembled either his anxiety on some other occasion or anything else. This inferiority is due in part to the fact that the manifestations of anxiety in behavior, including verbal reports, are so complicated by facts other than the anxiety itself, by, for example, the animal’s health, temperament, concomitant ideas and emotions, knowledge of language, clearness in expression and the like. It is due in part to the very low status of our classification of kinds of anxieties and of our units and scales for measuring the amount of each kind. Hence the variation amongst observers would be even greater than in the case of the toothache, and the confidence of all in their judgments would be less, and far, far less than their confidence in their judgment of John’s stature. The best possible present knowledge of John’s anxiety, though scientific in comparison with ordinary opinion about it, would seem grossly unscientific in comparison with knowledge of his stature or weight. Knowledge of the anxiety would improve with better knowledge of its manifestations, including verbal reports by John, and with better means of classification and measurement.

John’s knowledge of his own anxiety would be in part the same as that of the other observers. He too would judge his condition by its external manifestations, would name its sort and rate its amount on the basis of his own behavior, as he saw his own face, heard his own groans, and read the notes he wrote describing his condition. But he would also, as with the toothache, have data from internal sense-organs and perhaps from centrally initiated neural actions. In so far as he could report these data to himself for use in scientific thought more efficiently than he could report them to the other observers, he would have, as with the toothache, an advantage comparable to the advantage of a criminologist who happened also to be or to have been a thief, or of a literary critic who happened to have written what he judged. It is important to note that only in so far as he who has ‘immediate experience’ of or participates in or is ‘directly conscious’ of the anxiety, reports it to himself as thinker or scientific student, in common with the other nineteen, that this advantage accrues. To really be or have the anxiety is not to correctly know it. An insane man must become sane in order to know his insane condition. Bigotry, stupidity and false reasoning can be understood only by one who never was them or has ceased to be them.

In our last illustration, John’s thinking of ‘9 × 7 equals 63,’ the effect on John’s behavior may be so complicated by other conditions in John, and is so subject to the particular conditions which we name John’s ‘will,’ that the observers would often be at loss except for John’s verbal report. Not that the observer is restricted to that. If John does the example 217 × 69 in the usual way, it is a very safe inference that he thought 9 × 7 equals 63, regardless of the absence of a verbal report from him. But often there is little else to go by. To John himself, on the contrary, it is easier to be sure that he is thinking of 9 × 7 equals 63, than that he has a particular sort and strength of toothache. Consequently if we suppose John to be thinking of that fact while under observation, and the twenty observers to be required to identify the fact he is thinking of, it is sure that there might be an enormous variability in their guesses as to what the fact was and that his testimony might be worth far more than that of all the other nineteen without his testimony. His observation is influenced by the action of the neurones in his central nervous system as theirs is not, and, in the case of the thought ‘9 × 7 equals 63,’ the action of these neurones is of special importance.

Our examination of the way science treats these six facts shows no impassable cleft between knowledge of a man’s body and knowledge of his mind. Scientific statements about the toothache, anxiety and numerical judgment are in general more variable than statements about length, hair-color and body-temperature, but there is here no difference save of degree. Some physical facts, such as hair-color, eye-color or health, are, in fact, judged more variably than some mental facts, such as rate of adding, accuracy of perception of a certain sort and the like. So far as the lack of agreement amongst impartial observers goes, there is continuity from the identification of a length to that of an ideal.

Scientific judgments about the facts of John’s mind also depend, in general, more upon his verbal reports than do judgments about his body. But here also the difference is only of degree. The physician studying wounds, ulcers, tumors, infections and other facts of a man’s body may depend more upon his verbal reports than does the moralist who is studying the man’s character. Verbal reports too are themselves a gradual and continuous extension of coarser forms of behavior. They signify consciousness no more truly than do signs, gestures, facial expression and the general bodily motions of pursuit, retreat, avoidance or seizure.

Nor is it true that physical facts are known to many observers and mental facts to but one, who is or has or directly experiences them. If it were true, sociology, economics, history, anthropology and the like would either be physical sciences or represent no knowledge at all. The kind of knowledge of which these sciences and the common judgments of our fellow men are made up is knowledge possessed by many observers in common, the individual of whom the facts is known, knowing the fact in part in just the same way that the others know it.

The real difference between a man’s scientific judgments about himself and the judgment of others about him is that he has added sources of knowledge. Much of what goes on in him influences him in ways other than those in which it influences other men. But this difference is not coterminous with that between judgments about his ‘mind’ and about his ‘body.’ As was pointed out in the case of body-temperature, a man knows certain facts about his own body in such additional ways.