12 Animal Intelligence 



servers 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 x 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 moral- 

 ist 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, avoid- 

 ance or seizure. 



