Page:Mind (Old Series) Volume 11.djvu/526

 THE TIME TAKEN UP BY CEREBRAL OPERATIONS. 525 series of experiments. If red appeared the observer lifted his right hand, if blue his left. The times are given in Table XXIX., the pairs of colours used being red and blue, and green and yellow. The reaction on red and on green was made with the right hand, on blue and on yellow with the left. Each number gives the average of six series (78 reactions in the uncorrected series). TABLE XXIX. ] 3 ( ^ R V R' V R V R' V 27. XI. 2. XII. Red.... Blue... 291 296 27 27 289 296 18 18 342 332 39 25 322 320 32 22 1. 5. XII 289 25 286 17 354 32 351 18 Yellow 303 28 306 20 334 34 332 23 A 295 37 294 18 340 39, 331 24 False... 9 3 If from the average time for the four colours we substract the simple reaction-time, we find that it took B 145, C 190<r to dis- tinguish the colour and find the proper motion. If these times are compared with those given in the preceding section (Table XVI.) we find that it took B 18, C 34o- longer to send out the proper and corresponding motion, than the command sending out a motion already determined. As I have already remarked, the perception-process is slightly different in the two cases ; it being necessary in the first to see whether the light is red or blue, in the second only to recognise the red light. The results of the experiments show that there can scarcely be a difference in the times taken up by the two processes. Quite a similar method was used with letters, the observer lift- ing his right hand if A was present, his left hand if Z. The num- bers given in the Table are taken from six series. TABLE XXX. ] 3 ( i R V R' V R V R' V 4. 10. XII A... Z 328 339 27 23 324 336 18 15 379 382 42 34 370 379 30 22 A 333 25 330 16 380 38 374 26 False .... 8 3