533 J. M. CATTELL : TIME TAKEN BY CEREBRAL OPERATIONS. TABLE XLIV. Light. White Surface. Letters. Assoc. Sound. B 31. III. 7-30 a.m...' 157 12 IDS -2] 344 25 733 103 13!) 9 9-40 .... - 1 -1 -r> -4 + 10 + 2 -98 -17 -3 -1 1 p.m.... -14 -2 + 9 -4 7 + 9 -59 -11 + 11 + 10 2-50 ... -10 -3 + !> + 4 + 4 + 1 -2 -8 7 -2 6-55 ... + 1 -2 + 34 -3 + 12 + 6 -81 -39 + 3 + 2 8-50 ... + 5 + 1 4-20-2 + 37 + 5 -228 + 121 + 10 + 1 1. IV. 8-30 a.m.... + 17 -2 -10 +1 + 21 + 9 + 83 + 2 -16 -2 8 p.m.... + 7 + 3 + 2 -5 + 1 + 10 + 1 53 + 68 -2 + 5 C 26. III. 7-30 a.m.... 156 10 247 12 4?9 23 827 125 144 13 10-55 4-10 + 3 -17 + 4 -8 -4 + 9 + 8 + 2 -3 2 -40 p.m.... + 28 + 5 + 1 + 9 + 9
+ 12 + 43 + 15 + 1 7-20 ... + 19 + 1 -10 + 7 + 19 -3 + 58 + 5 + 15 + 3 9-20 ... + 33 + 7 + 6 + 9 + 37 + 3 + 163 + 23 + 19 -4 11-40 ... + 34 + 8 + 2 + 4 + 30
+ 111 + 10 + 11
27. III. 8-30 a.m.... + 27 + 1 + 6 + 7 -3 + 5 + 19 + 7 wanting 8 p.m.... + 20 + 5 -2 + 2 + 11 -3 -12 -41 + 23 -2 28. 8-30 am + 25 + 12 -1 + 5 -6 -3 + 42 + 44 -6 -1 The first result to be noted from the Table is the very slight effects of fatigue ; in no case is the time lengthened more than a couple of hundredths of a second, and the mean variation is but little increased. We reach the unexpected result that the pro- cesses which are the most automatic (naming the letters, and C's simple reaction-time) are the most affected by fatigue. The determinations made on the following day show that B had recovered from all fatigue ; in the case of C, however, the brain substance concerned in the simple reaction seems to have been so far exhausted that his reaction-time remained abnormally long for two days. I think these experiments show that it is possible to apply scientific methods to the investigation of mind. "We have determined the times required for those processes which make up a great part of our mental life, and found these times to be constant ; they are no more arbitrary, no less dependent on fixed laws than, for example, the velocity of light. I shall soon print an account of experiments going a step farther and determining the times of mental processes more removed from psycho-physical operations having to do with sensation and motion.
