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404 L. T. STEVENS : ON THE TIME-SENSE. the value of the indifference-point at '71 sec., as well as shown that the law of Vierordt is applicable, in general, to intervals con- siderably greater than 1'5 seconds. Their papers, however, deal mainly with the influence of contrast, the multiplicity of the indifference-point, and the validity of "Weber's law for the time- sense ; their valuable conclusions will not be reported, inasmuch as the experiments in question do not bear upon them. From this short and very incomplete account of previous experi- ments, it will be seen that in all cases the conclusion is drawn, that the natural tendency is to subtract from long intervals and to add to short intervals, in reproducing or estimating them. The conclusion drawn in this paper is exactly the reverse. With reference to the value of the indifference-point, however, my results and those of recent investigators are in harmony. I have no means of forming an opinion as to the cause of the discrepancy between my own results and those of others. The method used by Wundt's students is entirely different from mine. In one, comparison is made of two intervals, and the pro- cess is purely mental ; while the other consists in catching an interval and reproducing the same, and, of course, in doing so, certain physiological and psychological moments (the exercise of the wall, the origination of motor impulses and their transmission along efferent fibres, and the latent period of muscular contrac- tion), in addition to the mental process, enter into the experiment. Whether these factors enter and, if so, how, or whether (as is barely suggested by the anomalous results) fatigue and inattention may have entered more largely into other methods in a way to account for the previous results, seems to require further study. I regret that other duties prevent me from continuing the investigation, and I now publish my results, not with the intention of denying outright the correctness of previous conclusions, but with the hope that they will act as an incentive to others to proceed with the work, so as to obtain definite information of the possibly existing factors that are capable of so completely perverting the operations of our time-sense. Before concluding, I have to thank Profs. G. Stanley Hall and Henry P. Bowditch for their advice and assistance ; and also the other gentlemen who have kindly acted as subjects for experi- ment, or have otherwise assisted me. References. (1) Vierordt : Der Zeitxinn, (1868) ; cp. Wundt's Phys. Psych., P. 781. (2) Mach : Wundt's rhy*il. I'wlml. (Ite Aufl.), s. 765. (3) Kollert : Philosophische Studien, Ed. i., Heft. 1, s. 88. (4) Estel : Bd. ii., Hc-t't. 1, s. 37. (5) Melnier : Bd. ii., Heft. 4, s. 546. Boston, January 10th, 1885.