May 8, 1896.] 



SCIENCE. 



687 



combinations. 215 of tliese are pi-intecl 

 upon a sheet in miscellaneous order. A 

 certain one of these is singled out for iden- 

 tification and the subject is required to in- 

 dicate as many occurrences of this character 

 as he can detect within a limited time (90 

 seconds). In the first attempt Mr. Her- 

 mann did not fully comprehend what was 

 wanted, marking ofiF 10 right and 19 wrong 

 ones. In the second test he marked off 8 

 correct ones. Mr. Kellar marked off 7 cor- 

 rect ones in the first attempt and 11 in the 

 second. The general average of persons 

 succeed in recognizing about 8 forms in this 

 time. 



Quite a number of tests of the quickness 

 of movement and of mental processes were 

 made. For Mr. Hermann the maximum 

 number of movements of the forefinger 

 alone was 72 in 10 seconds, or 7.2 per sec- 

 ond, and of the forearm 75, or 7.5 per sec- 

 ond. For Mr. Kellar, forefinger 83 in 15 

 seconds, or 5.5 per second, and for the fore- 

 arm 127, or 8.2 per second. The average of 

 a large number of individuals for the fore- 

 finger movement was 5.4 per second, and 

 of a group often persons, tested more nearly 

 in the same way as were Messi's. Hermann 

 and Kellar, 4.8 per second. The average 

 forearm movement of the same ten persons 

 was 7.5 per second. It thus appears that 

 the movements for both Mr. Hermann and 

 Mr. Keller are rapid ; Mr. Hermann's fore- 

 finger movement being exceptionally so, 

 while Mr. Kellar's forearm movement is 

 the better. 



Passing to the ordinary forms of reaction 

 experiments, Mr. Hermann's reaction to a 

 touch upon the right hand was remarkably 

 short, especially for one who had never 

 been a subject for reaction experiments be- 

 fore. The average of 6 trials was 104 «• 

 (<T == YTffTr second) , with an average varia- 

 tion of 11 IT. Mr. Kellar's time was 129 rr, 

 with an average variation of 10 «-. For sound 

 reaction the time was: Hermann 163 it, vari- 



ation 32 IT ; Kellar 116 it, variation 25 <t. For 

 visual reaction, Hermann 126 n, with varia- 

 tion of 26 IT, or omitting one irregular result, 

 111 '7, with variation of 8 ^r ; Kellar 125 t, 

 variation of only 6 it. For a considerable 

 group of average individuals, reacting for 

 the first time, the following numbers have 

 been found : For touch, 172 t ; sound, 165 <t ; 

 sight, 176 ff. It thus appears that both of 

 the special subjects tested react far more 

 quickly than the average individual. An- 

 other form of reaction involving manual 

 quickness of movement was arranged as 

 follows : Two keys were placed three feet 

 apart, and the time measured that elapsed 

 between the touching of one and a move- 

 ment over to and touching the other. Mr. 

 Hermann's time for this reaction was 610 it, 

 with a variation of 76 o- ; Mr. Kellar's time 

 was 299 IT, with a variation of 23 <t. The 

 average of ten individuals making the same 

 test was 364 it, with an average variation of 

 32 IT ; but these ten individuals show con- 

 siderable variation amongst one another. 

 Mr. Kellar's time is thus somewhat below 

 the normal, although it is equalled by 6 of 

 the 10 persons tested, while Mr. Hermann's 

 time is unaccountably long. As a type of 

 reaction involving a choice, the distinction 

 of red and blue, associated with movements 

 of the right and left hands, was selected. 

 In this Mr. Hermann's time was 301 it, with 

 a variation of 64 «■ ; Mr. Kellar's time, 256 it, 

 with a variation of 56 it. For a simpler 

 choice I have an average record of 259 t, 

 and for the same reaction the average of 10 

 individuals is 297 it, with an average varia- 

 tion of 44 IT. 



A more complicated reaction involved a 

 movement with any one of the five fingers in 

 response to the appearance of the numbers 

 1, 2, 3, 4 or 5 behind the opening in a 

 screen. Mr. Hermann's time for such a re- 

 action was 901 IT, with a variation of 200 it ; 

 Mr. Kellar's time being 753 it, with a varia- 

 tion of 91 IT, The average time of 10 indi- 



