Page:Mind (Old Series) Volume 11.djvu/538

 THE TIME TAKEN UP BY CEREBRAL OPERATIONS. 537 TABLE XLIII. B C B C I C R V R V R V R V R V R V I 136 1 Q 139 15 XIV 147 q 151 10 I... 277 ?0 306 99 II 146 14 155 13 XV 147 9 151 8 II 287 25 308 22 III.... 144 11 150 9 XVI... 149 12 148 8 III.... 294 25 308 23 IV.... 145 16 149 10 XVII. . 152 12 154 12 IV.... 298 22 316 28 V 143 9 149 10 XVIII. 152 8 152 10 V 297 25 314 23 VI.... 142 13 149 13 XIX... 151 9 154 13 VL... 300 25 317 22 VII... 147 10 151 13 XX 148 10 151 12 VII... 292 21 318 24 VIII. 148 10 150 11 XXI... 150 13 146 9 VIII. 298 23 319 23 IX.... 155 13 149 7 XXII.. 152 12 150 10 IX.... 299 20 319 23 X 145 9 151 9 XXIII. 147 8 148 12 X 297 23 322 24 XL... 143 13 147 9 XXIV. 152 13 144 10 XL... 297 23 349 22 XII... 154 14 147 13 XXV... 150 13 144 11 XII... 293 20 322 23 XIII. 153 16 152 11 XXVI. 150 15 150 10 XIII. 295 22 317 23 A 148 12 149 11 294 23 316 24 It will be seen that, though the difference is not great, the first reactions of a series are the shortest. It seems that in the first experiments the observer involuntarily strains his attention more, and so gives shorter times. This is the more marked the less automatic the process is ; that is, with the white light than in the simple reaction, and in the case of B than in the case of C. The further course of the series shows no lengthening in the times or increase in the mean variation ; so the brain is not considerably fatigued by making (or refraining from making) twenty-six re- actions in succession, In order further to investigate the effects of fatigue, I made extended series of experiments in which 1950 reactions were made in succession, the observer reacting almost continuously from early in the morning until late into the night. Three series (78 reactions) were made with light, then three series (39 determina- tions, but 78 mental processes) in which white light was distin- guished and reacted on, then three series in which letters were seen and named, then two series in which associations were made, lastly three series of reactions on sound. This entire combina- tion of series was repeated six times. The experiments were begun both days at 7 '30 a.m. and were concluded in the case of C at 1*30 a.m., in the case of B at 11 p.m., short pauses being made for meals. One series of each variety was made the follow- ing morning and again in the evening ; in the case of C a further set of series the day after. In the Table I give the average time and mean variation of the first set of series, afterwards the increase or decrease as compared with these. I do not take up space to give the corrected series, as they scarcely differ from the others. 36