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{"created":"2022-01-31T13:30:05.119554+00:00","id":"lit28754","links":{},"metadata":{"alternative":"Studies from the Yale Psychological Laboratory","contributors":[{"name":"Moore, John M.","role":"author"}],"detailsRefDisplay":"Studies from the Yale Psychological Laboratory 3: 68-95","fulltext":[{"file":"p0068.txt","language":"en","ocr_en":"STUDIES OF FATIGUE.\nBY\nJohn M. Mooee, Ph.D.\nEffect of fatigue on binocular estimate of depth.\nEarly experiments.\nThe first apparatus consisted of a board about 1-J- meters in length into which were driven two knitting needles exactly one meter apart. Between the needles was a brass rod, supported by two small blocks of wood, on which was a sliding carriage with a needle driven into its center. A bead was placed on each of the needles. The beads were adjusted in a straight line and at the same height. The head of the observer was put into a support which kept the eyes in line and at the same height with the beads. He was told to look at the bead nearest him, then at the next, and then at the last. He was to judge of the equality between the distance from the first to the second and that from second to third. If the second bead was too near or too far away he moved it by a cord till the distances were equal.\nExperiments were made for several days upon myself and others. On looking at the beads six images were seen. The nearest pair were first united, then the second pair and finally the third pair. There were thus never less than five images present, which changed in position with every adjustment. The effort to combine the pioper images was constantly hindered by the distracting movements o the others. These double images interfered so much that in my o case I was unable to get more than twenty results at one sitting, o account of great fatigue.\t^\nEach experiment gave a record of the distance of the midd e ^ from the nearer one. Taking the position of the bead in tk\u00ae ^ experiment as the standard, its record was subtracted from following record. The results thus obtained show how muc middle bead recedes from the nearer one as fatigue comes on. ^ Thus three sets of experiments were made whose resu s ^ transformed into \u201c fatigue sets \u201d by subtracting the first reSU","page":68},{"file":"p0069.txt","language":"en","ocr_en":"Studies of fatigue.\n69\njach set from each of the following results in the same set. The averages of the three sets gave the results, 0, 12, 29, 35, 30, 50, 60, g5 98, 95) 113, H6 millimeters as the amount of increase over the first. Th\u00ae amount of error due to fatigue during these twelve experiments was equal to about the amount of error for 40 experiments according to the later method.\nWith others experimented upon, the double images likewise distracted the attention and hindered a satisfactory judgment. The observers never felt sure of the distance from one bead to the other, a\u00ab their attention was required to adjust the double images.\nThis was not the only objection to having the three beads before the eyes at one time. When the eyes were converged on the first, with the second and third double, there was formed a triangle of which the first bead was the vertex while the two images of the third were at the base. With this outline before the eyes, the second bead could easily be moved until its double images became the centers of the sides of the triangle. This could all be done without any movement of the eyes.\nFinal apparatus.\nA board, fig. 7, a little more than one and a half meters long and thirty centimeters wide, supported by three legs, served as the table.\nFig. 7.\nIV\n0ra ^le end at which the observer sat, at a distance of one-half a \u00aeeter, the first brass tube T was stationed, extending down through e board. In this tube was a knitting needle, on the upper end of ^*\u00b0h a cylindrical brass bead 10mm long and 9mm in diameter was ^ ened. On the lower end of the needle a small rod was fastened. q 6 needle had an up-and-down play of 45mm. Another bead as similarly supported at a distance of lm from the first. *>\u00cfOcralon\u00a3\nQg, was cut in the board between the two beads.\nA slot Over the","page":69},{"file":"p0070.txt","language":"en","ocr_en":"J. M. Moore,\n70\ncenter of the slot was a brass rod R, lcm in diameter, supported at either end by small blocks 2cm high. Upon this rod was a small brass cylinder D, closely fitting but free to move, which acted as a carriage for the second bead B supported similarly to the other two. It carried an index I which extended over a scale graduated in both directions from the center of the distance between the two beads. This carriage was moved by an endless cord passing over pulleys at the ends of the board. It also passed over a wheel W, whose axle was supported by two blocks under the table at a short distance from the front end. By turning the protruding axle the observer could place the middle bead wherever he desired. By pushing the lever L the first bead A could be raised and by pulling it the third bead C could be raised. This was done with the same hand which turned the roller for the second bead. From the rod F on the lower end of the second bead, a cord passed up behind and over the index rod I of the carriage, then through the slot S, under the table to a screw-eye in the front. This was used by the left hand and was kept stretched by a small weight.\nThe beads were hidden from the observer by a blackened upright board E. In this a slot 2ram wide and llom long was cut, at the height which the beads would have when raised. To prevent the eyes from looking down further on the third bead than on the other two, by virtue of the visual angle covering more distance, a black tin apron G was extended 150m out from the slot. The head was kept in the same position by putting the nose at a definite place each time.\nThe apparatus was placed on a large table and was raised or lowered so that when the observer was sitting erect, the eyes would be opposite the slot. The beads when raised were in the direct line of vision from the center of the slot. The nose having been put upon this middle point, each bead formed the vertex of an isosceles triangle made by the line of sight of the two eyes. Ko movements were necessary except those of accommodation and of symmetrical convergence.\nMethod of experiment.\nThe experiment began each time with the carriage of the second bead placed at the end of the slot nearest the observer. All bea were out of sight. By a push of the lever the first bead was raise.> its position was noticed and it was allowed to fall. By the cord the left hand the second bead was raised and dropped. Then by","page":70},{"file":"p0071.txt","language":"en","ocr_en":"Studies of fatigue.\n71\nU11 of the lever the third was raised and dropped. The judgment ^as made as to whether or not the second bead was in the middle. If not, the block was moved further away by turning the wheel and the experiment was repeated. This was done until the bead was judged to be in the middle.\nA few trial experiments showed that almost the same results would be obtained if the experiment began with the second bead at the near or at the far end ; but as my judgments always placed the bead nearer the farther end, it was best to bring the slide over the greater distance to prevent the judgment from being influenced by the distance moved. \u2022 Had it been moved otherwise the distance was short enough to have been remembered. Care was always taken to prevent the judgment from being influenced by the distance passed over by the carriage, or by the amount of cord passed through the hand, or by the number of revolutions of the wheel.\nThe distance of the first bead from the eyes was a half meter ; this is not short enough to cause any strain. The third bead was a meter and a half away and the middle point was 500mm from either extreme. The part of the scale graded from this point toward the eyes was called negative and the other positive ; they were indicated by the signs \u2014 and +.\nThe experiment was never continued to complete exhaustion. In the first experiments on myself, I continued until vision became very indistinct and the third bead was focused with great difficulty. This occurred about the fortieth experiment. Thereafter the set of experiments was ended at the fortieth.\nEach individual experiment resulted in a position of the middle bead somewhere near the middle point, or 0, between the two end-beads. Its divergence from this point was recorded in millimeters + or \u2014,\nObserver A.\nThe first question to be considered is the position of the estimated middle point for the first experiment on the successive days of work.\nThe results are : during May, 2V, 60, 33, 28, V4, 97, 83, 96 ; during June, 75, 48, 48, 81, 80, 80, 90, 74, 61, 76, 86 ; during July, 92, 97, !02, 92, 103, 121, 136, 126, 70, 104 millimeters, all being + or devinions beyond the true middle. In all the experimenting upon myself the second bead was never brought on the minus side and the nearest plus was 27mm. Thus in my normal condition the distance between the two beads was steadily overestimated.","page":71},{"file":"p0072.txt","language":"en","ocr_en":"72\n,7. df. Moore,\nThis change of estimation can be attributed directly to fatigue for the following reason. When I began experimenting on myself jn May, I was in excellent physical condition and my other work was not heavy. Much time was afterwards required for outside work and the pressure became so great that I could go to the laboratory only after the most exhausting labor. During the last few days of the experimenting, a feeling of general physical depression was experienced even at the beginning of the experiment. Further experimenting was postponed till June.\nThe June experiments were begun at the end of a month\u2019s work of the most exhausting character. The outside work had now narrowed to merely an employment which was not at all fatiguing but which prevented any rest. The wear of the previous severe strain could not be easily repaired. There was very little change in the physical condition and the record shows very slight variation.\nTable I.\nFatigue in binocular estimate of depth.\nNo. of record.............. 1\t2\t3\t4\t5\t6\t7\t8\t9\t10\t11\t12\t13\nMay, average.............  0\t3\t9\t20\t17\t28\t19\t21\t30\t47\t43\t48\t62\nJune, average............. 0\t2\t4\t6\t13\t18\t10\t18\t18\t20\t37\t41\t33\nMay and June, average______ 0\t2\t6\t12\t15\t22\t14\t19\t23\t32\t40\t44\t45\nNo. of record..............14\t15\t16\t17\t18\t19\t20\t21\t22\t23\t24\t25\t26\nMay, average...............54\t61\t64\t71\t77\t83\t79\t62\t60\t76\t83\t75\t84\nJune, average............ 31\t31\t41\t36\t42\t48\t44\t44\t48\t49\t48\t51\t44\nMay and June, average______41\t44\t51\t50\t56\t63\t58\t52\t53\t60\t63\t61\t61\nNo. of record ........27\t28\t29\t30\t31\t32\t33\t34\t35\t36\t37\t38\t39\t40\nMay, average..........92\t78\t81\t87\t96\t91\t104\t88\t82\t109\t86\t99\t91\t105\nJune, average.........41\t43\t49\t58\t54\t52\t61\t60\t58\t66\t56\t65\t62\t65\nMayand June, average-62 58 62\t70 71\t67\t78 71 67\t72 68 78 74 80\nDuring July the work was steady and experiments on the eyes were made two or three times each day till Aug. 1. The eyes were becoming greatly fatigued. The exceptional character of the ninth experiment in July is due to the fact that Sunday intervened between the eighth and ninth with a general rest of forty-four hours. The records for July show a large increase over the records similarly taken in May and June. The painful sensations in the eyes testified to fatigue. In the beginning of the experiment, at the first convergence, a severe pain was often felt over the eyes. When any near object was focused the same painful feeling was experienced.\nA suggestion is here offered to the teachers in primary and sec-","page":72},{"file":"p0073.txt","language":"en","ocr_en":"Studies of fatigue.\n73\nondary schools. Where proper supplies cannot be furnished by the community, a large amount of copying from a blackboard is required. Small children are frequently compelled to do this work, although the fatigue is particularly injurious in their case. They are not able\n'X^Sirial numtrCrof txftrantnt Y, trror in mm.\nI,,At ay JY.Juni.\nV- June.\nFig. 8.\nto grasp a sentence and write it from one glance ; they must continually change their convergence by looking to the board and back. Even larger pupils are very often required to copy Latin, Greek or German from the board. These languages not being familiar, the","page":73},{"file":"p0074.txt","language":"en","ocr_en":"74\nJ. M. Moore,\nconvergence must be changed for almost every word. If sucjj is continued many minutes in succession, or for a short time day, the evil effect will be seen in those pupils whose eyes are strong. They will be afflicted with headaches and will be greatl disturbed in the preparation of lessons.\tr\nThe second question for consideration is the effect of the special fatigue in each experiment of the set of forty. In the previous par agraphs only the first experiment of the set was considered. With this first experiment taken as a standard, any deviation of the succeeding results from the same figure can be attributed to fatigue resulting from the previous experiments of the same set. Accordingly for each set the difference between each experiment and the first experiment was computed ; thus, -f- 3 for the second experiment would indicate that the middle point was placed 3mm further from the eyes than in the first experiment. The result of the first experiment was thus used as a zero-point from which to reckon the effect of fatigue in the following experiments.\nThe average divergence of the second result from the first was +3 for the eight sets in May, that of the third was +9, etc. The complete list is shown in Table I, all the results being +.\nThe table and the curve, fig. 8, show an increase from the very beginning. In the curve for May, in the second experiment there is an increase of 3mm over the first, in the third 9mm, and in the fourth 20mm, and so on. In the curve for June, 2mm, 4mm, and 6mm are the increases of the second, third, and fourth experiments. In the composite curve for May and June the increases are 2mm, 6mm, 12mm. From this it seems evident that fatigue begins very early in the experiment. As each single experiment represents, on the average, four distinct trials at accommodation and convergence it is safe to say that fatigue sets in within ten trials, though it may not be detected by any painful sensations for more than twice that number.\nThe increase for May is much more rapid than that for June. This is true for all the records. May ends with an increase of 105 . > while June reaches only to 65m,n. While this may be attributed in part to external circumstances or physiological conditions, it is due to a large extent to practice, as has been pointed out by Fechneb-Continued practice would enable the subject to make many experiments before exhaustion than were made in this series, form of the curve would continually vary until practice had reac\n1 Fechner, lieber den Gang der Muskel\u00fcbung, Ber. d. k.-saehs. Ges. 4. \"Wisa., \u00ae phys. Kl., 1857 IX 113.","page":74},{"file":"p0075.txt","language":"en","ocr_en":"Studies of fatigue.\n15\nmaximum. The general form would not be so much changed, tut certain parts of the curve would be stretched out as in the case 0f those who are not easily fatigued.\nThe composite curve shows that fatigue changes our estimations very rapidly in the early experiments, while the successive increments decrease toward the end of the set. The curve rises more rapidly in the first half than in the last. The change in the last quarter is not nearly so marked as in the first quarter. Could the experiments be continued to complete exhaustion, the curve would assume a parabolic form. That is, the observer will continue to increase the overestimation until the bead reaches a certain point, beyond which it cannot be moved without the observer, however fatigued, knowing that it is nearer the third than the first bead.\nThe presence of rhythm is very marked. It disappears somewhat in the composite curves, but it is very striking in the individual records. There seems to be a rhythm of fatigue throughout the whole work. There are exceptions but they are few. Rhythm has been found in all the work in which fatigue comes in to modify the results. The following record of a single experiment shows the phenomenon. The figures indicate the number of millimeters of overestimation at each placing.\nIt runs 81, 75, 42 (which is exceptional as they generally rise from the beginning), 74, 104, 120, 54, 85, 87, 97, 119, falls to 102, but rises immediately to 134. Some parts of the remainder show similar fluctuations : 105, 100, 137, 138, 125, 129, 137, 144, 141, 115, 125, 150, 146, 114, 164, 155, 150, 138, 186, 142, 159, 123, 172, 171, 133, 148, 199. This fluctuation reminds us of Lombard\u2019s experiments on muscular fatigue.1\nThe figures in Table I are averages for experiments extending over a whole month. Thus, the number 105 for the 40th experiment is the average of all the 40th experiments for the month of May. It becomes necessary to know how the individual results differ from the average. This knowledge is obtained from the mean variation. Each individual result used in an average had its difference from that average determined ; thus, each 40th experiment during May was c\u00b0mpared with 105 and the difference noted. Then these differences Were averaged, giving the mean variation ; thus a mean variation Was obtained for the 40th experiment, and likewise for each of the others. The results are given in Table II.\n1 Lombard, The effect of fatique on voluntary muscular contractions, Am. Jour.\nVh\u201e 1890 in 24","page":75},{"file":"p0076.txt","language":"en","ocr_en":"76\nJ. M. Moore,\nThe table and the curve, fig. 9, show the same fact as the fatigue curve itself, although not so marked. The curve for May begins with eight and rises to forty-one. The curve for June begins with sixteen and does not reach higher than twenty-nine, and then closes near its beginning. In the fatigue curve for May there is a much larger increase than in that for June. As fatigue increases work becomes more irregular. This will be found also in the results of the mental and muscular work which will be described later.\nTable II.\nMean variation in binocular estimate of depth.\nNo. of exper............ 1\t2\t3\t4\t5\t6\t7\t8\t9\t10\t11\t12\t13\nMay...................   0\t8\t19\t14\t19\t21\t17\t16\t26\t21\t16\t25\t22\nJune .................   0\t16\t15\t15\t8\t22\t16\t17\t14\t16\t14\t19\t22\nMay and June............ 0\t13\t17\t16\t12\t12\t17\t17\t20\t23\t15\t22\t27\nNo. of exper. ......... 14\t15\t16\t17\t18\t19\t20\t21\t22\t23\t24\t25\t26\nMay.................... 12\t26\t24\t34\t30\t36\t41\t23\t26\t33\t29\t27\t27\nJune .................  12\t20\t16\t15\t13\t13\t19\t19\t16\t19\t15\t19\t13\nMayandJune..............16\t25\t21\t27\t24\t26\t33\t21\t21\t27\t25\t25\t16\nNo. of exper........27\t28\t29\t30\t31\t32\t33\t34\t35\t36\t37\t38\t39\t40\nMay.................33\t26\t34\t34\t34\t36\t29\t36\t24\t41\t30\t35\t40\t29\nJune--------------- 22\t23\t29\t18\t19\t20\t18\t29\t24\t23\t22\t19\t19\t17\nMayandJune----------29\t26\t32\t27\t31\t27\t27\t32\t26\t35\t27\t30\t32\t26\nWhat is the source of this irregularity ? By an electrical stimulus it might be proven that the fatigue was central, as was found by Mosso1 in muscular fatigue. Fatigue in the physical organism might cause an extension or contraction of the estimated distance, but it could not explain the irregular element. This must be accounted for from a purely psychical standpoint. The will, attention, and memory were involved in every decision. When fatigue had fully begun, it required considerable effort to hold the attention on the position of the beads and to retain in mind the two distances to be compared. Often it became impossible to remember with clearness the first distance, and unless the decision was made immediately, only two dim perceptions, one of which was fast escaping, were present. The fatigue evidently affects the attention and thus causes this irregularity.\nDuring the first week of July six sets of experiments were made\n1 Mosso, Ueber die Gesetze der Erm\u00fcdung, Du Bois-Reymonds Arch. i. Physiol., 1890\n111.","page":76},{"file":"p0077.txt","language":"en","ocr_en":"Studies of fatigue.\n77\nto determine the relation which memory hears to the results. The subject would focus on the first bead, then the second, and then wait five seconds, and again focus the second, and then the third.\nA i\\\\\n\\ i \\i\nJUVE\nFig. 9.\nThe result is seen in the following average record of the fatigue : V 6, 13, 11, 7, 6, 13, 13, 20, 21, 21, 18, 28, 19, 60, 23, 39, 36, 67, 40, 49, 38, 63, 53, 56, 54, 61, 58, 53, 42, 43, 62, 53, 63, 65, 57, 52, 50, 67,","page":77},{"file":"p0078.txt","language":"en","ocr_en":"78\nJ. M. Moore,\n59mm. The effect is found in the greater irregularity. As in the preceding case, the increase is produced but according to no law About the same result was found when the time was extended to ten records.\nWhy should this exhaustion come so early ? Why should a fatigue of 52ram appear in the twentieth placing while in the regular work it was not reached before the fortieth ? The explanation is perhaps as follows. When the subject raised the first bead and then the second, he formed a mental picture of the distance. He waited five seconds and raised the third bead. Now, two positions are held in memory and the third is before him. The two memory-positions will approach each other as the time passes, and the second bead will appear nearer than it did when it was focused. The subject is not conscious of this mental operation. So he pushes the second bead farther from him than he would have done had no time elapsed. The first placing shows this phenomenon. As fatigue comes on, our memory images grow dim much faster and consequently we increase the distance very rapidly. Fatigue has the same effect on memory distance as the passing of time. Why exhaustion comes so early will be spoken of later.\nObserver B.\nThis observer was a college student. A large number of trial experiments was made before his records assumed a regular form. His irregularity was due to his manner of focusing. His first efforts were made, as he said, in trying to find the middle point, and as a result he invalidated his work by following several different methods. Finally, after much insisting that he locate each bead mentally by looking at it and at nothing else, his curves began to take a more regular form. However, his mean variation continued large. This seems to indicate an inferior accuracy in judging depth by binocular movements. The large mean variation doubtless covered in the record much of the misplacement that was due to fatigue.\nOut of his numerous records twenty consecutive ones were selected. In every case the second bead was placed nearer the third bead than the first. The averages of the twenty fatigue sets made as in pre-ceding work is as follows : 0, 3, 7, 2, 11, 6, 18, 17, 15, 22, 29, 30, 25, 27, 29, 31, 31, 24, 32, 33, 34, 33, 33, 32, 32, 45, 31, 26, 25, 29, 31,27, 36, 28, 34, 26, 33, 31, 29, 34, 27. As in the previous case, each number represents the amount of retreat of the bead in the successive","page":78},{"file":"p0079.txt","language":"en","ocr_en":"Studies of fatigue.\n79\nexperiments beyond its place at the first experiment. The curve of results is shown in fig. 10.\nHis fatigue curve does not reach the height of that for Observer A although he testifies to fatigue in these notes: \u201ceyes ache;\u201d \u201c eyes feel tired ; \u201d \u201c extremely tired, eyes worn out ; \u201d \u201c eyes felt heavy and tired ; it was hard to focus them.\u201d The only explanation of the diff\u00e9rence in the records seems to be that the average of the first records in all the experiments on Observer A is 72, while the average of his is 175, which is near A\u2019s fatigue limit. His fatigue range\nXy stria f number of exf trimint T error in mm.\nJO J5 2.0 25 30\t35 40\ncould not extend so far without bringing the second bead near the third. Fatigue would not produce so great a change within that small space. With a longer distance the curves would be likely to come nearer each other.\nB\u2019s greatest fatigue was generally reached several experiments before the set closed. In the average curve the highest point is at the twenty-fifth experiment. This is true of the majority of the individual curves. At this point he would generally complain of being \u201cunable to go much further.\u201d He would soon feel better and his record would show a less distance from the center than in the immediately preceding experiment.\nFluctuations were present as in the case of Observer A.\nPractice had approached its maximum influence before his records were ended. The time required to place the bead was much longer than for other observers. It required twenty minutes for A to make the set of forty, while it required thirty minutes for B. He was","page":79},{"file":"p0080.txt","language":"en","ocr_en":"80\nJ. M. Moore,\nslow in decision and would often focus twice or more without moving the beads. This extra focusing may account for the fact of his reaching a maximum fatigue so early as the 25 experiment\nThe mean variations for his fatigue curves show a slight increase for successive dates. His irregularity in the individual records was much greater than that of the preceding observer.\nDiscussion.\nWhat was the condition of the eyes while one bead was being lowered and the other raised ? Did they hold their convergence or did they assume a parallel ? To determine this, a fourth bead was set up just one meter from the third. The first bead was raised, noticed, and then dropped. The eyes were then focused on the fourth. The second was raised and dropped, and the eyes were again focused on the fourth. After the same action with the third, the judgment was made as to whether or not the second bead was in the middle. At the twentieth experiment the eyes were exhausted, while they were accustomed to forty experiments with the three beads. The attention was so distracted that it was difficult to place the second bead. The time required for focusing was largely increased. The same results were found when a mark on a distant wall was used instead of the fourth bead. The observations show that the eyes rarely assume a definite intentional position, but rather an easy position from which the next converging can be done with the least difficulty. This position is presumably a parallel one.\nIn making these experiments by putting up a fourth bead to determine whether or not the eyes remained converged between the focusings, the attention was greatly distracted. So, to find the effect that the fatigue of attention had on the estimate of distance, this bead, marked by the letter D, was placed at a distance of one meter from the third and in the same line of vision. Ten sets of experiments were made as just described, the average of whose fatigue sets is as follows : 0, 0,-2, 7, 13, 13, 16,24, 22,20, 30,44,32, 33,50,47,52, 54, 60, 54. The highest effect of fatigue is 60mm, which is about the same as that found in the regular sets. But this is the result of only twenty placings, the regular sets containing forty. The time required to make these twenty experiments was eighteen minutes while the time of the forty was only twenty. In these the firmest attention was absolutely necessary to judge the distance and hold in mind the position of the beads. When the first was focused, then the fourth, the second, then the fourth again, the distance from the first to the","page":80},{"file":"p0081.txt","language":"en","ocr_en":"Studies of fatigue.\n81\nsecond was forgotten unless the memory was kept riveted on the various positions. The fourth greatly interfered by distracting the attention. As fatigue entered, the work grew more difficult, the attention was more easily distracted, and as a result the variation became much larger in the individual experiments. The muscles of convergence could not have been very much more fatigued by extra fixation. The additional fatigue must have been due to the strain on the attention.\nComparison with atmospheric changes.\nAs the season was early summer, the windows were generally open and the conditions within the room were about the same as without. The observer at the United States Weather Station, which is about 300 meters from the laboratory, furnished me with the temperature, humidity and barometer markings. These fairly represented the conditions of the room used.\nIn Table III the fatigue column was found by subtracting the average of the first five of each set from the average of the last five. This was done for each experiment for the days in May and June and the results were placed in the order in which the experiments were made. The temperature and barometer readings were taken every hour. The humidity at the Station was registered only at 8 a. m. and 8 r. m. and so it was necessary to interpolate for the hour required. The humidity may not be correct, as it does not follow arithmetical rules.\nBy comparing the fatigue column of Table III with the columns representing the temperature, humidity, and barometer markings, it is at once seen that the fatigue was not controled by any one of these atmospheric conditions. On the first day, when the amount of the fatigue was the greatest, the barometer was exceedingly high. The second greatest fatigue has the second highest barometer. The second day shows an increase in temperature (but the temperature at that point would not be depressive), a slight decrease of humidity and a decided decrease in the pressure, while the fatigue is greatly reduced. On the third, the humidity and pressure decrease, the temperature increases and the fatigue increases. The first two are 11 \u00b0t sufficiently high to produce any evil effects, while a temperature \u00b0f 84\u00b0 so early in the summer in a northern climate will prove depressing. Throughout the experiments the law seems to hold tl-ne, that when temperature, humidity and atmospheric pressure are 6","page":81},{"file":"p0082.txt","language":"en","ocr_en":"82\nJ, M. Moore,\nfree to act, the fatigue is accelerated or retarded by the combined increase of any two of the three influences. But a large increase of temperature with a small decrease of humidity and pressure -will increase the fatigue. Fatigue will be increased by a heavy increase\nTable III.\nComparison of fatigue with atmospheric conditions.\nFatigue.\tTemperature.\tHumidity.\tBarometer in inches.\n147\t60\t73\t30.24\n89\t77\t69\t29.89\n101\t84\t65\t29.69\n104\t61\t68\t30.05\n87\t48\t79\t30.02\n43\t51\t69\t30.00\n54\t75\t76\t29.64\n83\t71\t80\t29.85\n90\t80\t90\t29.88\n95\t82\t90\t29.86\n66\t86\t76\t29.86\n64\t88\t76\t29.85\n59\t91\t66\t29.84\n68\t93\t68\t29.81\n34\t91\t69\t29.80\n51\t60\t98\t30.04\n73\t80\t95\t29.83\n51\t78\t84\t29.83\n52\t76\t96\t29.93\nof any one of these against a small decrease of the other two. Also a large decrease of one will decrease fatigue against a small increase of the other two. If the subject were put into a room where two of these influences could be kept constant while the other could be varied, it would probably be found that an increase of temperature, humidity or pressure would tend to increase the amount of fatigue, provided, of course, the experiments were begun at what might be termed the normal point of each.\nEffect of fatigue on monoculak estimate of depth.\nPerspective vision with one eye is generally imperfect, obscure and inaccurate. It has been held that the sensations of accommodation are not sufficient for any estimate of the depth of objects wit one eye.1 In the experiments here described all secondary helps were\n1 Hillebrand, Vas Verh\u00e4ltnis van Accommodation u. Konvergenz zur Tiefenlohalm tion, Zt. Psych. Phys. Sinn., 1890 VII 97.","page":82},{"file":"p0083.txt","language":"en","ocr_en":"Studies of fatigue.\n83\neliminated as far as possible in order to cause the judgments to be made from the sensations of accommodation. The same apparatus was used that was used for determining with both eyes the effect of fatigue on the estimate of depth. The slot through which the observer looked was reduced to 3cm in length, so as to permit the use of only one eye, the left, and to hold that in the same line of vision.\nf/umidlti\nFig. 11.\nThe other eye was not closed but left free. As it was within 3cm of the black shield there was nothing on which to focus and the attention was given entirely to the seeing eye.\nThe experiments were made upon myself and Observer B during the month of July. At first there was great difficulty in accommodating or focusing. The beads would not become clear and sharp at","page":83},{"file":"p0084.txt","language":"en","ocr_en":"84\nJ. M. Moore,\n\u2022once. Several sets were made before the judgments could be relied on. The first record and the average of the first five records in each set are given in Table IY.\nThe results show an increasing tendency toward placing the middle bead beyond the middle. This is similar to the result for binocular vision and for nearly all fatigue sets.\nThe averages for fifteen fatigue sets taken on three observers are shown in Table Y, the fatigue set being formed, as before, by subtracting the first record from each of the following ones.\nThe form of the curves in fig. 12 is not very unlike that found when both eyes were used. The greatest increase over the first\nTable IT.\nFirst record and average of first five\nNo. of set - - -\t.. 1\t2\t3\t4\t5\t6\t7\nObserver A, ) first record j\t62\t72\t50\t47\t80\t26\t46\nObserver A, ) first five j\t'\u25a0 81\t81\t63\t57\t96\t39\t60\nObserver B, first record\tf 2\t5\t122\t53\t107\t112\t125\nObserver B, first five\tj- 37\t19\t93\t64\t94\t92\t146\nrecords in monocular estimation.\n8\t9\t10\t11\t12\t13\t14\tIS\n73\t137\t83\t135\t72\t68\t114\t123\n79\t133\t82\t128\t93\t63\t96\t11!\n150\t135\t137\t136\t175\t205\t171\t\n142\t89\t212\t153\t175\t207\t183\t\nexperiment comes within the first twenty experiments. The curve after that time takes more nearly the parabolic form corresponding to that pointed out in the preceding section.\nThe mean variation of the individual results from the general\nmi\t(V ~\nresult is somewhat larger than that in binocular work.\nThe effect of\nfatigue on the variation is not quite so marked, yet there is a larger variation toward the close than at the beginning. Fatigue affects the accuracy of the judgment. In the individual experiments the variation from one to the other is very much greater than that in the estimation with both eyes.\nFrom the fifteen sets of Observer A, whose average has been given in Table Y, the following sample record is given to show the individual peculiarities. It runs as follows : 26, 44, 46, 20, 59, 72, 78, 77, 119, 49, 54, 88, 39, 44, 56, 62, 92, 60, 110, 98, 54, 72,132, 80, 10 , 105, 88, 92, 78, 125, 80, 120, 146, 160, 126, 88, 131, 128, 141, 160. This is a fair representative of the series. The amount of variation from one to another is easily seen. The dropping from 119 to was due likely to a mistaken judgment in the former. Such irreg1^ Iarity is to be expected much more than the wave motion, whic","page":84},{"file":"p0085.txt","language":"en","ocr_en":"Studies of fatigue.\n85\nto a large extent apparent. A gradual increase or continued variation would be more easily explained than the rhythm which nature seems to introduce. No cause for this phenomenon can be ascribed to any known external conditions. Some of the notes made were : \u201ccan scarcely see,\u201d this was when looking at objects after the experiment ; \u201c toward the last, the objects grew too dim,\u201d the power of convergence was greatly decreased ; \u201c focusing not clear, especially toward the last ; \u201d \u201c hard to focus toward the last.\u201d As regards the right eye, which was not used, these notes were made :\nTable V.\nFatigue in monocular estimate of depth.\nNumber of exper. __\t... i\t2\t3\t4\t5\t6\t7\t8\t9\t10\nObserver A \t\t... 0\t\u2014 2\t8\t12\t9\t9\t21\t27\t29\t20\nObserver B \t\t\t... 0\t1\t-2\t\u20147\t-4\t10\t\u2014 20\t1\t12\t13\nObserver C \t\t\t... 0\t9\t19\t26\t36\t44\t51\t43\t52\t54\nNumber of exper.-.\t... 11\t12\t13\t14\t15\t16\t17\t18\t19\t20\nObserver A \t\t\t...36\t33\t30\t40\t34\t40\t39\t48\t45\t41\nObserver B \t\t..-10\t5\t14\t2\t15\t9\t11\t-3\t-4\t-3\nObserver C\t\t\t... 65\t63\t79\t10\t69\t66\t74\t64\t61\t71\nNumber of exper..\t... 21\t22\t23\t24\t25\t26\t27\t28\t29\t30\nObserver A\t\t... 50\t62\t54\t53\t55\t54\t59\t60\t48\t65\nObserver B\t\t..-11\t8\t1\t7\t21\t19\t14\t5\t1\t22\nObserver 0\t\t\t.... 69\t61\t71\t76\t85\t61\t75\t76\t80\t80\nNumber of exper...\t... 31\t32\t33\t34\t35\t36\t37\t38\t39\t40\nObserver A.\t\t\t... 52\t50\t66\t59\t57\t53\t71\t67\t67\t70\nObserver B\t\t... + 7\t14\t-1\t\u2014 1\t4\t6\t23\t4\t1\t-12\nObserver C\t\t\t... 91\t74\t75\t81\t87\t92\t89\t83\t99\t89\nNumber of exper\t\t... 41\t42\t43\t44\t45\t46\t47\t48\t49\t50\nObserver 0\t\t...103\t104\t82\t89\t92\t103\t106\t107\t98\t104\nThe numbers are positive unless otherwise designated.\n\u201c right eye pained as much as the left ; \u201d \u201c right eye felt worse till I got up, and then the left pained me very much.\u201d There is little doubt that jthe unused eye was accommodating and focusing with the seeing eye. It might be claimed that much assistance may have been received from its sensations of convergence. As its focus depended on the seeing eye, it is not clear how it could give any aid, although the claim that work with one eye is in reality nothing more nor less than work with both eyes is undoubtedly correct. The facts noted in this paragraph all refer to Observer A.\nTable V also shows the relations of fifteen fatigue sets taken upon Observer B. The result is very different from that just pre-","page":85},{"file":"p0086.txt","language":"en","ocr_en":"86\nJ. M. Moore,\nsented. No law of fatigue can be discovered. The reason for this can be found by examining the individual record. One of them begins with 107 but falls to 81, then to 54. Then it rises and falls again. The second twenty minutes show a slight increase but\nJiO -\n5 JO JS 20 25 30 35 40 4-5\nFig. 12.\naccording to no law. This irregularity is found in all the fifteen sets. The averages apparently represent this observer as very accurate and unfatigued, but. the enormous variations in the records show that this was simply due to counterbalancing errors in both directions. This was accounted for when the operator acknowledged","page":86},{"file":"p0087.txt","language":"en","ocr_en":"Studies of fatigue.\t87\nhis inability to get a clear focus. He could not properly estimate depth with one eye.\nTo determine further the effect of fatigue on monocular estimation of depth, experiments were made on W. H. L., a young man who had lost his right eye. A few months after the removal of the eyeball, the wounds healed and his left eye became serviceable. At first he had great trouble in seeing objects near him. He could not fix his eye for the near objects. He could not estimate the distance from one object to another behind it. In looking from the third story of a building in which he was working the curb-stone seemed to be le'vel with the street. This changed after a few months and he is now able to determine depth, according to his statement, almost as accurately as before he lost his eye.\nHe was free for experiment only at seven o\u2019clock in the morning and at eight o\u2019clock in the evening. After a few trials to acquaint himself with the use of the apparatus and to learn the exact nature of the experiment, he made seven records. From these the fatigue sets were formed whose averages are shown in Table V, Observer C.\nThe rhythmical movement is very manifest in all his records. With him fatigue increases the estimate of the distance between two objects lying in the same line of vision. The increase is not so rapid in the last as in the first part of the experiment. These conclusions agree with those obtained from the binocular work.\nThe accuracy of decision of this observer was somewhat surprising. Sometimes I manipulated the apparatus and moved it as he ordered. He could easily detect the \u201c too far \u201d or \u201c too near \u201d when the bead was moved more or less than he desired. His judgments were made entirely from what he saw and not from the noise of the slide or the amount of cord used.\nThe results here recorded conclusively show that fatigue of accommodation has an influence on localization in depth. If the conclusions of Hillebrand concerning the total failure of accommodation to aid a judgment of depth are to be accepted, as they apparently must be, it is very difficult to see any possible explanation for the fact that fatigue of accommodation influences such judgments.\nEffect of fatigue on the time of monocular accommodation.\nIn the Studies for 1893 Seashore1 gives the result of researches made on monocular accommodation-time. On page 69 he says : \u201c In\n1 Seashore, On monocular accommodation-time, Stud. Tale Psych. Lab., 1892-93","page":87},{"file":"p0088.txt","language":"en","ocr_en":"88\nJ. M. Moore,\nregard to fatigue, however, my results are contrary to the supposition. Experiments of some 300 accommodations\nusual\n\u2022\t-,\t,\t,\tone coo*\ntmuous set do not support that theory [increase of time]\nsoon sets in and may become very painful, but as long as the can accommodate clearly it causes a fluctuation in time which tends more to accelerate than to retard the velocity of accommodation The researches which I had carried out seemed to show the opposite result and in conjunction with Mr. Seashore the experiments were repeated.\nApparatus.\nThe apparatus was virtually that used by Seashore with, perhaps, some improvement. As my experiment was to determine the effect of fatigue, only one mode of accommodating was used, that from far to near.\nThe distance remained the same. From the far object to the near object the distance was 825cm while from the near object to the eye it was 23\u2122. The far object was a large capital E with a height of 25mm and the near object was a small capital e with a height of 7\u201c\u201c fastened on the slide of the camera shutter. The far point remained stationary while the nearer was presented or removed by a sudden movement of the shutter. A brass tube extended from the eye to the shutter. When the slide was up, the eye could see nothing except the large letter on the white back-ground. When the slide was down only the small letter could be seen. When the shutter fell, an attached copper wire made an electrical contact with a wire carrying a current through the spark coil to the battery. The other wire extended from the shutter through a closed circuit reaction-key, by means of which the current could be interrupted. The other arrangements for recording were similar to those used by Buss.\nThe slide was raised and the observer focused on the far object. The experimenter touched a key which was electrically connected with a sounder in the recording room. The recorder pushed down a key which closed the primary circuit. The experimenter now snapped the slide ; this made a dot on the smoked paper and then closed the circuit. As soon as the observer saw the small R c ear 1 and distinctly, he broke the circuit by the reaction-key, thus ma mg\n1 Bliss, Investigations in reaction-time and attention, Stud\n. Yale Psych. I<ab?\n1892-93 I 1 (1).","page":88},{"file":"p0089.txt","language":"en","ocr_en":"Studies of fatigue.\n89\nanother dot on the smoked paper. When the recorder saw the two\narks, he raised the key and kept out all further sparks until the fifth repetition of the experiment in quick succession. A record was thus made of the time of every fifth experiment. The wave leno-tbs between the two dots could easily be counted and the time of accommodation obtained. This time included the subject\u2019s regular reaction-time.\nThe observer was asked to use his stronger eye. The other eye was kept closed by the hand or by a bandage, as he might choose.\nHe sat with his back to a window which admitted excellent light on the nearer e.' The large E was illuminated by reflected light from a window in an adjoining room. Only those persons were used who were accustomed to being experimented upon. Only a few records were counted before all the .experiments were completed; thus no suggestion of the result could enter as a prejudice. Of the six persons taken, two had according to their own previous statements very healthy eyes, two the average, and two below the average ; I thus made sure that no diseased eye was used. All were faithful observers.\nFive sets of records in hundredths of a second were made on Mr. Seashore and myself ; the averages are shown in Table VI. In order to compare my results with those taken in 1893 by Mr. Seashore, every tenth experiment was recorded in my case.\nThe average duration of a set of experiments was twenty-seven minutes. Each set contained 300 accommodations or more. On account of the shortness of the drum only 70 accommodations could be recorded ; this was the original reason for recording every fifth result.\nIn the experiments on Mr. Seashore the time is decreased for the first four records ; this may be due to the fact that attention increases during that period. The curve then continues to rise till the thirty-fifth is reached. From there to the close very little increase is perceptible. This phenomenon is in perfect accord with the results previously spoken of. The experiment closed before the tvork became painful.\nOne of the persons experimented upon by Seashoke in 1893 was \u00aeyself. My record was the most nearly complete which he obtained. It was made May 4, 1893. Each tenth accommodation was recorded. I^ble VI shows the record complete. A slight increase is evident. Fatigue had not manifested itself in any painful sensations. The \u00ae\u00b0te made then I copy here entire, \u201c I found no trouble in seeing","page":89},{"file":"p0090.txt","language":"en","ocr_en":"90\nJ. M. Moore,\nthe object at any time. I held my right eye closed by its own lid muscles. When I left the chair and looked at the objects in the room, the eye could not accommodate so easily as usual, although I felt little fatigue while at the tube. The temperature of the seeing eye was higher than that of the other. At one time I felt a little pain in the upper part of the eye but my attention was called to something else and I felt the pain no more. When I quit reacting\nTable YI.\nNo. of exper.\t\t 1\t6\t11\t16\t21\t26\t31\t36\t41\t46\t51\t56\nSeashore \t\t\t35\t34\t32\t29\t33\t38\t45\t42\t44\t60\t50\t50\nMoore, 1893 .\t\t 36\t\t35\t\t36\t\t30\t\t26\t\t32\t\nMoore, 1894 ,\t\t30\t\t31\t\t32\t\t31\t\t31\t\t52\t\nNo. of exper.\t\t61\t66\t71\t76\t81\t86\t91\t96\t101\t106\t111\t116\nSeashore \t\t\t 41\t49\t44\t61\t58\t54\t64\t57\t58\t51\t48\t38\nMoore, 1893 .\t\t37\t\t35\t\t32\t\t30\t\t39\t\t35\t\nMoore, 1894 .\t\t\t\t33\t\t\t\t46\t\t48\t\t42\t\nNo. of exper.\t\t121\t126\t131\t136\t141\t146\t151\t156\t161\t166\t171\t176\nSeashore \t\t\t54\t63\t70\t40\t56\t62\t58\t65\t67\t64\t77\t70\nMoore, 1893 .\t\t46\t\t34\t\t39\t\t38\t\t55\t\t37\t\nMoore, 1894\t\t 48\t\t58\t\t42\t\t51\t\t41\t\t53\t\nNo. of exper.\t\t181\t186\t191\t196\t201\t206\t211\t216\t221\t226\t231\t236\nSeashore \t\t\t58\t54\t61\t75\t68\t61\t79\t82\t72\t62\t65\t58\nMoore. 1893 .\t\t 54\t\t45\t\t39\t\t30\t\t34\t\t48\t\nMoore, 1894\t\t 70\t\t65\t\t71\t\t79\t\t57\t\t98\t\nNo. of exper.\t\t241\t246\t251\t256\t261\t266\t271\t276\t281.\t286\t291\t296\nSeashore \t\t\t58\t51\t55\t69\t61\t64\t47\t55\t71\t62\t62\t87\nMoore, 1893 .\t\t 34\t\t31\t\t45\t\t48\t\t40\t\t43\t\nMoore, 1894 .\t\t 64\t\t53\t\t61\t\t\t\t\t\t\t\nNo. of exper.\t\t\t.301\t311\t321\t331\t341\t351\t361\t371\t381\t391\nMoore, 1893 .\t\t\t_ 43\t42\t43\t45\t43\t50\t47\t54\t43\t46\nI thought I could have gone on much longer, but I found that for twelve minutes my eye felt the fatigue, and at times a slight pain, or at least uneasiness, was perceptible in a part of the eye.\u201d\nFrom these it is easily seen that fatigue had not appeared to any great extent. On Aug. 8, 1894, other experiments were made similar to the former ones. My physical condition was not so good as when the first was taken. Each tenth accommodation was recorded. I was unable to go beyond the 261st experiment because of severe pain in the eye. Table YI. gives this record also. The recoi begins with 0.30s and closes with about 0.61s. The time is double Fatigue had thus greatly increased the time.","page":90},{"file":"p0091.txt","language":"en","ocr_en":"Studies of fatigue.\n91\nThe three results are shown in fig. 13.\nOther experiments, not included in the table, were made in which every fifth accommodation was recorded. They begin with about 0.40s and close with about 0.85s. These records show only about 240 accommodations in a set, as the eyes bad been weakened by other work. The farther object would become indistinct, or pains would give warning to close. The experiments on myself show conclusively that fatigue does increase the time of accommodation.\n.X , serial number of experiment Y, accommodation-time in\nhu.ndr\u00a3d,tls ofjO. second\n\\ J V\nFig. 13.\nNumerous records taken on four other persons show, without exception, a large increase in the time as fatigue progressed. This fact can be considered as definitely established, Seashoee\u2019s statement to the contrary being founded on experiments that did not continue long enough. His method was also less fatiguing because he allowed more time between each accommodation.\nSince only every fifth accommodation was recorded, the rhythmical movement which was so prominent in the previous work does not appear so plainly in this. The records in this seem to be much more irregular than in the preceding work. Mr. Seashore, however, made this note among other introspective observations. \u201c There seemed to be a rhythmic fluctuation of the time and effort it took to accommodate clearly.\u201d This introspective observation is corroborated by that of another observer. Could the experiments have been recorded singly it is highly probable that the rhythmic fluctuations would have been fully as prominent as in any other work. If the rhythm ls due to attention there is no reason why it should not appear.","page":91},{"file":"p0092.txt","language":"en","ocr_en":"92\nJ. M. Moore,\nEffect of fatigue on the maximum rate of voluntary\nMOVEMENT.\nDresslar1 found that the time of making 300 taps varies with the mental and physical condition of the individual, and that fatigue caused a decrease in rapidity when the experiment was extended beyond 300 taps. Bliss2 3, with superior methods, showed the effect of changes in the state of attention upon the rapidity of making taps, and proved that fatigue caused a decrease in the rate soon after 100 taps.\nIn the following experiments the methods were still further improved. The subject was seated in an isolated room which admitted neither light nor sound except when desired. There was a table of convenient height on which to rest the arm. The arm was strapped firmly to a block of wood reaching beyond the elbow. The end of the block was so cut and shaped as to fit the palm of the hand, and thus to let the hand grasp it without any inconvenience. No part was free to move except the index finger. A rod clamped to the table acted as support for a reaction-key previously described.\u2019 This key was fastened upside down by the clamp. The primary circuit for the spark coil passed to the binding post at the bottom of the key and to the movable slide. A spark was thus made at every upward movement of the slide. The registering was done on the drum by sparks directly on the time-curve written by a marker connected with the 100 v. d. electric fork. With the key thus connected the circuit was closed when the finger was in a partially bent or natural position. The adjustable slide was set so as to give an excursion of 5mm. The record was made when the finger began an extensor movement.\nThe subject was to begin when warned by a click from the sounder at his side and to continue to tap as rapidly as possible until his finger could move no more, or until told to stop. The finger was never completely fatigued because sufficient records could not be gotten upon the drum. I once made 480 taps but am quite sure that I could not have made 100 taps more at the close of any record, for it was always with great difficulty that the last 50 or 75 were made.\n1\tDresslar, Some influences which affect the rapidity of voluntary movements, Am. Jour. Psych., 1891 IV 514.\n2\tBliss, Investigations in reaction-time and attention, Stud. Yale Psych. Lab., 1892 1893 I 45-49.\n3\tScripture and Moore. A new reaction-key and the time of voluntary movement, Stud. Yale Psych. Lab. 1892-93 I 88.","page":92},{"file":"p0093.txt","language":"en","ocr_en":"Studies of fatigue.\n93\nThe usual experience was as follows : Pain was first felt in the muscles of the forearm, then in the upper arm. Suddenly the blood rushed to the face and head, and the temples were filled with sharp pains. The whole right side (the work was done with the index finger of the right hand), seemed to partake of the trouble. After the experiment was completed, the arm seemed paralyzed. I could not even handle the record-sheet with safety. The arm, especially the forearm, and often the shoulder would feel painful for a half hour afterward. Restoration was not complete in less than two hours and a half.\nThree records were made on myself. The individual taps of each record were placed in successive groups of 10, and the average of each group was calculated. For the final results the average was taken of the three original averages for each group. Such a condensation of results was necessary because the 3 records gave 480 X 3 \u2014 1440 individual records whose relative values could not well he grasped, and also because the changes within a group of 10 were so small that the course of the fatigue function became evident to the eye only when the unit of the argument was made larger than a single tap.\nThe final averages in my\town\tcase\texpressed in\tthousandths\tof a\nsecond, ran as follows :\t200\t195\t192\t194\t198\t198\t208\t221\t229\t221\n230 238 230 231 235\t240\t244\t244\t248\t246\t25V\t241\t273\t254\t256\n248 240 240 246 243\t249\t263\t255\t301\t290\t276\t275\t277\t321\t320\n300 340 325 322 288\t293\t308\t359.\nIn the records the fatigue is manifested by the time the seventieth tap is reached. In the final average it is clearly shown at the seventh group, which includes the 71st to 80th taps.\nA professional cornet player, who had not played for a year, showed no fatigue before 150 taps had been made. A woman who played on the piano, showed no fatigue until 200 taps were made. She affirmed that she felt no fatigue, but the incipient fatigue had left its traces in the records beyond the 200th tap. There was a very slow increase, and consequently even at the end it was not very large.\nIn my record the rate of tapping increases for the first three groups of ten. Then there is a decrease in the rate for the next six groups. Then it increases slightly, and then decreases again. A rhythm seems to manifest itself. It is seen better in the individual records like the one shown in fig. 14 than in the general one.\nA summary of the figures of the experiment made Nov. 11, 1893,","page":93},{"file":"p0094.txt","language":"en","ocr_en":"94\nJ. M. Moore,\n10 a. m., is given in Table VII, as illustrating the process of fatigue In this experiment 470 taps were recorded. These 470 taps were put in groups of ten and their averages taken. By comparing these averages, the rate of tapping, and its increase or decrease, are readily seen throughout the series. N gives the number of the set of ten records.\nThe mean variation was found by taking the average of the individual deviations from the average of its own group of ten. This does not always increase steadily with increase in the average ; but after fatigue has become very prominent the variation becomes very large.\nTable VII.\nN\tAv.\tMv.\tN\tAv.\tMv.\tN\tAv.\tMv.\n1\t193\t8\t17\t338\t13\t33\t304\t94\n2\t191\t9\t18\t239\t16\t34\t279\t67\n3\t179\t6\t19\t249\t12\t35\t322\t75\n4\t193\t12\t20\t246\t9\t36\t238\t12\n5\t191\t11\t21\t239\t15\t37\t231\t15\n6\t189\t12\t22\t238\t5\t38\t293\t72\n7\t197\t7\t23\t227\t12\t39\t288\t37\n8\t217\t25\t24\t250\t22\t40\t239\t13\n9\t210\t9\t25\t238\t13\t41\t302\t66\n10\t206\t16\t26\t245\t23\t42\t314\t69\n11\t222\t20\t27\t234\t12\t43\t336\t91\n12\t226\t9\t28\t233\t16\t44\t295\t33\n13\t228\t9\t29\t232\t11\t45\t277\t33\n14\t212\t21\t30\t221\t11\t46\t304\t56\n15\t230\t6\t31\t226\t16\t47\t406\t75\n16\t224\t12\t32\t232\t18\t\t\t\nMy tap-time cannot be closely compared with those of Bliss and Dresslar, who simply tapped and released a telegraph key, whereas I moved a slide 5mm and back. My time is that of the complete excursion, the time up, the time at rest, and the time down combined.\nThe results of this record on myself are presented in lig. 14. The fluctuating nature of the tapping is made evident ; quite noteworthy are the extremely long taps that occur with increasing frequency toward the end. These fluctuations probably bear some relation to those observed by Lombard1 when weights are repeatedly lifted.\n1 Lombard, The effect of fatigue on voluntary muscular contractions, Am. Jour. Psych., 1890 III 24.\nLombard, Effet de la fatigue sur la contraction musculaire voluntaire, Archives italienne de biologie, 1890 XIII 371.\nLombard, Influences which, affect the power of voluntary muscular contractions, Jour. Physiology, 1892 XIII 1.","page":94},{"file":"p0095.txt","language":"en","ocr_en":"Studies of fatigue.\n95\nThe records thus prove that fatigue lengthens the time required for repeating the voluntary movement of tapping at a maximum rate, that the increase is not a steady but a fluctuating one and that the irregularity in the repeated movement also increases.\nX , serial number of ex fan mint\nV, time of tap in thousandths of a second\nFig. 14.\nGeneral conclusions.\nThe conclusions for each kind of experiment have been given in the appropriate sections. Here I wish to call attention to the two general chararacteristics of fatigue, namely, an average change directly in the phenomenon influenced and a change in the range of variation around the average. The average change might be called the coefficient of inaccuracy and the mean variation the coefficient of irregularity ; then the law can be stated that both the coefficient of inaccuracy and the coefficient of irregularity are increased by fatigue. It would hardly be justifiable to give a more precise quantitative form to the law except by saying that the increase is most rapid at first, and then steadily slower. A final point to be noticed is the increasingly frequent recurrence of extreme results as fatigue progresses.","page":95}],"identifier":"lit28754","issued":"1895","language":"en","pages":"68-95","startpages":"68","title":"Studies of fatigue.","type":"Journal Article","volume":"3"},"revision":0,"updated":"2022-01-31T13:30:05.119572+00:00"}