Page:Mind (Old Series) Volume 11.djvu/402

ON THE TIME-SENSE. 401 Diversion of attention and small experience are, therefore, regarded as the cause of the great irregularity in the size of the errors that is observed in the last four Tables. The first three Tables, however, possess a certain quantitative as well as qualitative value ; and in these it is observed that the error gradually increases in amount, as the indifference-point is moved from, in either direction. As to the manner of varia- tion, examination of the curves (p. 398) reveals two remarkable points. (1) The constant zig-zag of individual records. This is a peculiarity which was observed in all the curves plotted. 1 Of the series of curves published, the upper one shows about 19 cases only out of about 140 in which two sequent variations are in the same direction. This would seem to indicate that an interval is judged more correctly after it is completed than before, and that correction is made for its error in the next reproduction, accord- ing to a standard which the mind carries but to which the hand (or perhaps the will during the interval) cannot be accurately true. The origin of this peculiarity would, therefore, appear to lie not in the judgment, but in the execution. (2) In all of the curves plotted, there were observed more or less distinctly still larger and more primary waves. The prominence of these varied greatly ; in some of the curves they were apparently absent, in others they were decidedly marked. On p, 398, three such waves are plainly seen in the first, and one each in the second and fourth curves ; in the third and fifth they are not so evident, but their existence is shown by enlarging these curves. Taking into con- sideration all of the curves that were plotted, it may be stated that these waves are no more prominent for one interval than for another, as the published curves would indicate. The length of these waves, expressed in fractions of a minute, varies, in the majority of cases, between '6 and - 9 min., and averages '73 min. 2 This rhythmical variation seems to be not in the execution, but rather to have its origin in a rhythmical variation of the standard carried in the mind. That this is connected with the rhythmical changes in the nutritive condition of the cerebral centres, as pro- duced by the vaso-rnotor rhythmical constriction of arterioles, it would be rash to deny or afiirm, or, perhaps, even to suppose. B. Irregular Experiments. The following are all of the irregular experiments, given in the form best adapted to show the direction and amount of variation: 1 24 in number, representing experiments from Cases I., IV., V., VI. 2 The lengths of those detected in the curves obtained from Case I. vary between '63 and - 86 min., and averaged '73 min. The average of 15 from Case IV. is '73 min.; of these 12 vary between '62 and *88 min., and the values of the remaining 3 are -56, T06, and -91 min. 11 waves from Case V. vary between '62 and -95 min., and average '72 min. 9 from Case VI. vary between '61 and '89 min., and average '73 min. 27