Page:Mind (Old Series) Volume 11.djvu/243

 242 J. M. CATTELL I TIME TAKEN BY CEREBRAL OPERATIONS. on B gave especially long times ; afterwards he learned to accom- modate himself better to the conditions. All these experiments show that in the case of C the reaction is more thoroughly reflex than in the case of B. Contrary to my expectation the reaction on sound seems to be more lengthened by distracting the atten- tion than the reaction on light ; it requires less effort to react on the sound, the reaction seeming to take place quite of itself, and we -know that it is easy to make motions in time to sound- rhythms. I made further series of experiments in which ' Jetzt ' was said and the chronoscope was set in motion as usual, but the light was produced only half the time. My thought was that the subject could not put his brain-centres in the maximum state of unstable equilibrium, lest the motor impulse should be discharged in the case where no stimulus was forthcoming. The averages in Table XI. are from 13 and 10 reactions, as measurements were only made in half the experiments of the series. TABLE XI. I } ( i R V R' V R V R' V 27. II 153 18 147 10 174 22 165 8 28 148 154 10 23 148 148 6 15 166 142 18 6 160 143 8 5 165 157 20 9 157 156 10 7 154 153 12 12 156 150 6 8 A 155 16 151 10 158 14 155 7 The delay here caused is related to the will-time to be con- sidered later on. From these experiments we see that ordinary degrees of atten- tion do not greatly affect the length of the reaction time. We find, further, grounds for assuming that the cortex is not concerned and that perception and willing are not factors of the reaction- time. It is not necessary to perceive the stimulus before the motor centre can be excited ; and the willing not of necessity given in consciousness is done before the stimulus occurs, and consists in setting the brain-parts concerned in a state of readi- ness. (To be continued.)