Page:Mind (Old Series) Volume 11.djvu/383

 382 J. M. CATTELL : from the other; in the second each colour was distinguished from ten colours. With blue and red electric lights (the above- mentioned Puluj's tube seen through coloured glasses) I got as perception- and will-time 75<r for B, 109 for C. 1 In most of my experiments however, with aid of the gravity- chronometer, I used daylight reflected from coloured surfaces, these exciting the pro- cesses with which our brain is occupied in our daily life. Eed and blue and green and yellow were taken in pairs, the coloured surface being 3 x 30 mm. The numbers in Table XVI. give the average of six series. TABLE XVI. ] 5 ( -i R V R' V R V R' V 27. XI.-2. XII. Red.... Blue... 278 287 22 19 272 280 11 17 322 291 40 24 324 288 26 16 I -5 XII. .. . Green.. 268 <>6 265 18 313 3? 312 21 Yellow 276 26 273 16 297 31 300 20 A 277 93 272 15 306 3-7 306 21 AV 2 8 Ten colours were further taken in pairs, as indicated in Table XVII., and the time required to distinguish the one from the other determined. If we average together the results given in Tables XVI. and 1 These are the only experiments described in this section which had been previously made ; Bonders (Archiv f. Anat. u. Physiol., 1868) found the time to be 184lmrt. The latter may have been made mi luly short through the frequent occurrence of premature reactions (the number of false reactions is not given) ; at all events I consider their method of calculating the averages dangerous, they ignoring what reactions they saw fit. They do not give the number of measurements made in the series, but in the model u in the appendix, we find that in one 22 reactions were used, in one on the perception of light only 9 ; we may therefore assume that in the latt>- .'-rhalf of the reactions ignored. If the mean variation of the reactions used in this series be cal- culated, it will be found to be 6 (smaller, I imagine, than the mean error of the recording apparatus) ; the mean variation of the corresponding B of simp!-- reactions (from which determinations had also been omitted) is 12rr. When a re made up in this way any results de.-ired can be obtained.