SOME CURIOSITIES OF THINKING. 731 



It is evident that Inaiidi lias a mind developed largely in one 

 direction, but undeveloped in others. 



Another instance of a lightning calculator may be mentioned, 

 because he presents a wholly different method in his mental ac- 

 tion. I refer to M. Diamandi, who has recently been examined 

 carefully by Prof. Binet, of Paris.* Diamandi is able to perform 

 wonderful feats of mathematical calculation with great rapidity, 

 but he can not make his calculations until the numbers given 

 him are written down. In other words, he is a visualist ; he calls 

 to mind numbers as they appear when seen. He says the num- 

 bers appear as if written on a mental table, which he sees and 

 reads when he is asked to repeat numbers from memory. If Dia- 

 mandi receives a problem by ear, he hesitates, appears em- 

 barrassed, commits errors, and demands a repetition. It is neces- 

 sary for him to call up the visual image of the numbers heard. 

 But when a problem is given in writing, he glances at the paper, 

 then closes his eyes, makes an effort to call these numbers to 

 mind, quickly goes through the calculation, and reaches the re- 

 sult, which he seems to himself to read off from the mental tablet. 

 According to his statement, the numbers appear to him as if 

 written in his own handwriting. Thus, if the problem is written 

 in ink on a white paper, the figures in his mind appear in the 

 same black color on white; but if it is written with chalk on 

 a blackboard, it is thus that the result comes to his mind. His 

 time of calculation is slightly longer than that of Inaudi, 

 but he is equally exact. Some ingenious tests were 

 made by Binet to prove the different methods of 9 7 6 4 5 

 calculation in the two men. Several numbers were 6 3 2 14 

 written beneath one another, forming a square, thus : 5 4 3 7 8 

 and these were committed to memory by the two 3 8 6 5 1 

 men. Diamandi looked at them. They were read to 7 9 14 2 

 Inaudi. They were then asked to give the numbers, 

 reading them downward instead of across and diagonally instead 

 of across. Diamandi, having the visual picture, was able to do 

 this in half the time of Inaudi, who had to call to mind the sounds 

 and make selections. ' i 1 



The more the processes of thought in such minds are analyzed 

 and contrasted with those in normal minds, the more apparent it 

 becomes that each individual has his preference m mental im- 

 agery, and that in each person the mind habitually works more 

 actively through one sense than through the others. This dis- 

 tinction was most acutely drawn by Charcot, who classified 

 people into " visualists "-those whose recollections were chiefly 

 of things seen, who had to read a name in order to remember it ; 



* Kevue Philosophique, March, 1894. 



