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SCIENCE. 



[Vol. XV. No. 374 



SCIENCE: 



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groL. XV. NEW YOEK, Apbil 4. 1890. No. 374. 



CONTENTS: 



The Color op Fishes 



G. Brown Goode 211 

 TTatttral History Garden and 



Aquaria for Boston 213 



Stammeeikg 216 



.Jamaica International Exhibi- 

 tion, 1891 217 



Notes and News 217 



Mental Science. 



The Time Sense....- 218 



Tisual Space Measurements 218 



Health Matters 

 Insanity in Australian Aborigi- 



219 



Dietary for the Nervous System , 219 

 Removal of Warts by Electroly- 

 sis , -219 



The Dangers of Hypnotism 219 



Yellow-Fever at Key West 220 



Book-Retiews. 

 Physiognomy and Expression .... 220 



Amonq the Publishers 220 



Letters to the Editor. 

 Heat and Ventilation 



S. H. Woodbridge 223 

 Sound- English. A. Knoflach ... 224 

 Do the Barclayan Descriptive 

 Terms occasion Obscurity? 



Burt e. Wilder 224 



MENTAL SCIENCE. 



The Time-Sense. 



A GREAT deal of experiment and discussion lias been expended 

 srpon the means by which we estimate time-intervals. Different 

 -observers have obtained quite opposite results, and the entire 

 problem seems to become more complex as study is expended 

 upon it. The usual form of experiment consists in reproducing 

 ■various intervals, as produced by the beats of a metronome or 

 otherwise, as accurately as possible under different conditions. 

 The difference between the true interval and the average of the 

 ^reproduced intervals is then calculated, and measures the con- 

 stant error; while the average deviations of the several reproduc- 

 ttions from their mean measures the variable error. The intervals 

 tfhuB tested were usually very brief ones, rarely being as long as 

 aaaatEUte. On the other hand, we have an idea of time from the 

 arelafive filling-out of the interval with mental experiences. A 

 time during which much has happened seems long : one during 

 (which little has happened seems short. The latter may be re- 

 ga.rdeda3 a truly mental mode of estimating intervals; but it will 

 <be readily seen that it is only roughly approximate in character, 

 and is not applicable to such small intervals as those usually ex- 

 ^rimented upon. What, then, is the means by which we gain 

 ^ur motions of the duration of these short artificial time lengths ; 

 ■auch, for instance, as we employ in music and other rhythmical 

 occupations? This is the problem that Dr. Mtinsterberg has re- 



ce ntly studied in quite an original way. i His reflections upon the 

 matter led him to the opinion that for these brief intervals we 

 have no time-sense in the strict sense of the word, but that our 

 estimates depend upon the feelings of tension, of arrest or delay, 

 of ordinary physiological functions ; and according as the end of 

 the interval comes upon the rise or the fall of this tension- wave 

 will a time-interval change its character. It is rather difficult to 

 more accurately specify the subjective feelings which one experi- 

 ences in waiting for intervals or in following thera, but one fac- 

 tor most readily observed is the variation in breathing. We have 

 all had some experience in the change of the breathing-rate under 

 different emotions. Breathing, too, being one of the most con- 

 stant bodily rhythms, it is not improbable that this affects our 

 notions of time. To test this. Dr. Mtinsterberg arranged his ap- 

 paratus in the usual way, first giving an interval varying from 6 

 to 60 seconds, and then having the subject mark off an interval 

 equal to it: the average error in so doing was 10.7 per cent. He 

 now had the experiments so arranged that the second sound, 

 closing the t)riginal interval, came at the same respiratory phase 

 as the first or opening sound of the interval : then the error was 

 only 3.9 per cent. In this series the sound closing the original 

 interval was at the same time the sound opening the re- 

 produced interval. In a following series of experiments each 

 interval had a separate opening and closing sound. When no 

 attention was paid as to the concurrence in the respiratory phase 

 of the opening and closing sounds, the error was 24.0 per cent, 

 while when this was taken into account the error was only 5.3 

 per cent. In a third series the attention was purposely withdrawn 

 from the respiratory and tension feelings, and the time judgments 

 became utterly confused. While these experiments are too few 

 to be taken as at all decisive, they certainly suggest a very inter- 

 esting field of research, and, furthermore, open out some possi- 

 bility of explaining the various results of different observers. 



Visual Space Measurements. 



The sense that above all others gives us our knowledge of ex- 

 tension in all the dimensions of space is the sense of vision ; but, 

 as we approach the problem more carefully, we see that there are 

 several modes of perceiving sensations of length by the eyes. 

 There is, first, the passive impression of a length upon the retina, 

 which is analogous to the impression on the skin when an object, 

 such as the edge of a ruler, is in contact with it.- In both cases 

 it is very essential to the notion of extension thus formed on 

 what part of the skin or the retina the image is impressed. There 

 are finely and coarsely sensitive portions of both skin and retina; 

 and the general law is, that the same amount of objective stimu- 

 lation will give a more extended sensory effect upon the more 

 finely sensitive surface. The centre of the eye is by far the most 

 sensitive portion, and hence we habitually turn the eyes so that 

 the object to be seen falls upon it; and it is the space sense of this 

 portion of tlie eye that is usually tested. We have, again, the 

 perception of space from the muscular effort needed to move the 

 eyes so that the beginning and end of the length shall successively 

 fall upon the fovea or central spot. In both these cases we must, 

 to complete our estimate of length, take into account the distance 

 of the object from the eyes ; for size and distance are inversely 

 dependent upon each other, arid each becomes inferrible only when 

 the other is known. Again, we have two eyes, which we ordi- 

 narily use together, but which we can use separately. The dis- 

 tances judged may be varied to an equal extent ; they may be of 

 any stated length within ordinary limits, — may be complete contin- 

 uous lines, a series of points, or simple terminal points marking 

 off a distance between them ; they may be horizontally, vertically, 

 or diagonally arranged ; they may be symmetrically or asymmet- 

 rically situated with reference to the central axis of the eyes ; 

 and so on. It is evident, then, that we exercise our power of 

 estimating distances by the eye in a large number of complex 

 ways, and that to introduce system into the problem of how these 

 estimates are made it is necessary to test the space-sense of the 

 eye under different and definite conditions. This Dr. Mtinster- 

 berg' has recently attempted by the following method. Two 

 small squares of cardboard are seen on a green ground with a 

 1 H. Miinsterberg, Beitrage zur Experimentellen Psychologie, Heft 2. 



