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{"created":"2022-01-31T13:15:09.746791+00:00","id":"lit28770","links":{},"metadata":{"alternative":"Studies from the Yale Psychological Laboratory","contributors":[{"name":"Gilbert, J. Allen","role":"author"}],"detailsRefDisplay":"Studies from the Yale Psychological Laboratory 2: 40-100","fulltext":[{"file":"p0040.txt","language":"en","ocr_en":"RESEARCHES ON THE MENTAL AND PHYSICAL DEVELOPMENT OF SCHOOL-CHILDREN,\nBY\nJ. Allen Gilbert, Ph.D.\nInfant development during the ages from 3 to 6 has been treated rather extensively, but so far as systematic scientific work is concerned, very little has been done in the study of the child during the years spent in school except in the line of bodily growth in weight, height, chest-capacity and the like. In measuring mental processes almost nothing has been done. The work of Bolton1 * on the growth of memory in school-children has brought out a valuable subject but would have been of far greater value had its statistics, which were obtained from careful work, been presented in more intelligible form. The subject of voluntary motor ability has been treated by Bryan.3 Hearing has been investigated by Chrisman.3\nLast year I carried through a series of tests on school-children to determine their sensitiveness to differences in pitch,4 and through this and the problems it suggested I was led to continue my investigations on a much larger scale in order to aid in that analysis of mental phenomena which is so necessary to an understanding of child-psychology. The present investigation was undertaken with the determination to carry through a regular set or series of accurate mental and physical tests upon school-children from 6 to 17 years of age.\nThe work has occupied most of my time during the academical year 1893-1894, the larger part of the fall term being spent in the invention and construction of apparatus used in taking the tests. In the furtherance of my work I am specially indebted to the following persons : to Dr. E. W. Scripture, who has charge of the Laboratory and was always ready to assist any endeavors at honest work ; for\n1 Boltox, Growth of memory in school-children, Am. Jour. Psych., 1893 IV 919.\ns Bryan, On the development of voluntary motor ability, Am. Jour. Psych., 1893 V 123.\n8 Chrisman, The hearing of children, Ped. Sem., 1893 II 39T.\n4 Gilbert, Experiments on the musical sensitiveness of school-children, Stud. Yale Psych. Lab., 1893 I 80.","page":40},{"file":"p0041.txt","language":"en","ocr_en":"Mental and physical development of school-children.\t41\nhis assistance I am truly grateful ; through his suggestions I was led to take up this investigation. To Mr. V. G. Curtis, superintendent of schools of New Haven, for the permission to enter the schools with my tests and for his kindly interest. I wish also to express my gratitude for the kindness and accommodation offered by Miss Web-ster, Messrs. Camp, Hurd and Thomas, principals of Welch, Dwight, Winchester and High Schools respectively; to Miss Treat, assistant at Welch for the time spent on tests (1) to (3), together with all the teachers at the respective schools who were helpful during the months occupied in taking the tests ; to Dr. C. B. Bliss, fellow and assistant at the Psychological Laboratory, for much of his time and many suggestions in the preparation of apparatus and prosecution of my work throughout ; to Mr. Hogan, the laboratory mechanic, for his assistance in. the construction of apparatus. To Professor Williams I am indebted for the idea embodied in the suggestion-test. Valuable suggestions were also received from Professor Ladd, who has throughout shown a kindly interest in my work.\nMethods and apparatus.\nEach child was tested in the following respects : muscle-sense, sensitiveness to color-differences, force of suggestion, voluntary motor ability, fatigue, weight, height, lung-capacity, reaction-time, discrimination-time and time-memory. Ten sets of special apparatus were constructed for each of the first three tests.\nTest (1) : Muscle-sense.\nIn this test each set of the apparatus consisted of ten weights varying from 82\u00ae to 100\u00ae in steps of two grams each. The weights were brought to the exact weight within 50m\u00ae. In order to get at mere muscle-sense or sensitiveness to weight, which is the aim of this test, heat, cold and roughness, which would distract the attention from this one sensation of weight in consciousness, must necessarily be avoided. To avoid heat and cold, cartridge shells were used, giving a paper surface, which is a non-conductor. Uncapped shells were cut in two, giving a cylinder 2.3cra in diameter and 3.80m long. These wer\u00e8 filled with lead disks and brought to within 100m\u00ae of the weight desired. In Order to avoid sensations of roughness, they were painted with asphalt, which leaves a hard glazed surface, raising the weight to within 50mg. A cylinder of the size named and filled as described makes a weight comparatively heavy and still of","page":41},{"file":"p0042.txt","language":"en","ocr_en":"42\nJ. A. Gilbert,\nsufficiently small size to be grasped easily endwise between the thumb and finger by a six-year-old child. In cutting the lead disks with which the shells were filled, the punch was so constructed as to press the disk into convex-concave shape before cutting it from the sheet of lead. These were placed with concavity to concavity and on being pounded down of course flattened out and consequently became of diameter large enough to press firmly against the side of the shell, thus avoiding any jostling sideways within, while they were also bound tightly one by the other, thus avoiding any jostling endwise. To get them of different weights sufficient cartridge-wads were used in place of lead disks. Each weight was marked by a secret sign to indicate its weight. For each set a box was then made of appropriate size in order to avoid any mixing of the sets in taking the tests.\nIn taking the tests the lightest one, marked by a white speck on the end and weighing 82* was used as the standard. The child received the box of weights and was told to sort out all those which seemed to him to be of exactly tbe same weight as the one with the white speck on the end, lifting them endwise between thumb and finger. To avoid the effects of fatigue on the sensitiveness to weight, each child was given only two trials on each block, lifting it and the standard alternately. The successive steps between the weights being two grams, the number of blocks selected as being of the same weight when multiplied by 2 would indicate in grams the threshold for discrimination to weight for that child.\nTest (2) : Sensitiveness to color-differences.\nJust as in the preceding test we were in search of the threshold for discrimination to weight or least perceptible difference in weight, so, in this test it was the aim to find the threshold for discrimination to color or the least perceptible difference in shade of one color. This test consisted of a series of ten shades of red so closely graded that no two successive colors or shades could be distinguished except by an experienced eye. Gray would have been preferable and in fact was tried previously to red, but owing to the fact that all goods are bleached with sulphur, no matter how well scoured before dyeing, traces of red could be found running through the gray.\nTen pieces of woolen cloth of fine texture were first dyed a suitable red by a practical dyer under my supervision. After the ten pieces were removed from this coloring solution, which left them all exactly","page":42},{"file":"p0043.txt","language":"en","ocr_en":"Mental and physical development of school-children. 43\nof the same color, a very small portion of dye was added to the boiling vat, thus making the fluid slightly darker. One of the pieces was again boiled in this, making it, when removed, very slightly darker than before. To this last solution was again added a small portion of dye in which a third piece was boiled and so on, adding for each successive piece of cloth an equal portion of dye and giving thus a Series of shades each differing from the others in a very slight degree. Each of this series of ten was then fixed firmly in a ring so as to exhibit the color and yet protect it from being handled. This ring was a hollow cylinder with a narrow shoulder on one end, the edge of which was beveled so as to avoid any shadows being thrown on the color. The colored cloth was stretched firmly across the end of a circular block which was driven into the ring, holding the color firmly against the shoulder. The circle in which the color was exposed was 3cm in diameter. The castings were then painted a dull black so as to avoid any reflection of light which might affect the color. Each block was then marked with a secret mark according to the place it held in the series. To avoid getting them mixed in taking the tests, a small box was made for each set of ten.\nIn taking the tests the block containing the lightest shade, painted white on the bottom to distinguish it, was used as the standard with which to compare the rest. The child was given a box containing one set and told to pick out all those shades of red which were exactly like the one painted white on the bottom. The number of those selected as being alike, including the standard, was then recorded. The number of colors picked out would indicate the threshold for discrimination to color for that child and by averaging the individual results the discrimination for the respective ages was obtained.\nTest (3) : Force of suggestion.\nThe aim in this test was to measure the effect of our ideas of a thing formed by the sense of sight upon those formed by the muscle-sense, in particular to get the effect of bulk in a thing upon our judgment of what it should weigh. As a first attempt, a set of ten blocks was made, each weighing 55K with an accuracy of 50me. All were 2.8cm thick but varied in diameter from 2.20m to 8.2cm in a geometrical series, in order to make the sensations increase in an arithmetical series according to Weber\u2019s law. On taking a number of tests with this set, asking the subject of the","page":43},{"file":"p0044.txt","language":"en","ocr_en":"44\nJ. A. Gilbert,\nexperiment to arrange them in order according to their respective weights, the decision was universal that the smallest one seemed heaviest and the largest one lightest, the others ranging between those two extremes with weights inversely proportional to their size. Now, in order to measure the amount of the suggestion offered by the bulk of the blocks, all being of the same weight in reality, a series of fourteen blocks was made, each being 2.8cffi long and 3.5cm\u2019 in diameter but all of different weights, ranging from 15\u00ae to 18* in weight. In order to get the different weights in the same sized blocks, holes were bored out of the center of a size directly proportional to the weight desired and filled with lead. This could then be easily bored out till the exact weight for each was reached. The lead was then concealed by a cartridge-wad, which also served the purpose of a center to the block on each end by which to grasp it when lifting. The position of each block in the series of fourteen was then marked plainly on one end.\nIn taking the tests for measuring the amount of suggestion offered by the difference in bulk, the very large weight and the very small weight were given to the child in connection with the series of fourteen blocks, the weight of the large and small standards being unknown to the child. He was asked to pick out of the fourteen blocks the one that seemed to him to be of the same weight as the small standard and also the one of the same weight as the large standard, lifting them endwise between the thumb and finger. The small block was first lifted; then the end-one of the 14 blocks was lifted. If it was apparently lighter, the second block of the 14 was tried. If this was also lighter, the third was tried. This was continued till that block of the 14 was reached which was apparently equal to the.small block. Its number was noted. Then the large block was compared successively with those of the 14 till an apparently equal one was reached. The weight of the small one was' the same as that of the large one. The amount of suggestion offered by the difference in bulk, could then be measured in grams by taking the difference in weight between the two blocks chosen as being the same weight as the large and small standards respectively. One heavier than 55* was always chosen for the small one and one lighter than 55s was always chosen for the large one, as will be explained in the discussion of results.\nThe first three tests just described were taken on desks adapted to the size of the child, thus subjecting all to the same influences in lifting. The desk was of such height as to throw the fore-arm parai-","page":44},{"file":"p0045.txt","language":"en","ocr_en":"Mental and physical development of school-children. 45\nlei with the floor. These first three tests were given to the child in the order in which I have recorded them, thus throwing the color-test in between the two weight-tests, giving no chance for the fatigue of test (1), should there be any, to be carried over into test (8),\nTest (4) : Letter-memory.\nThis was omitted because of the impossibility of accurate work with letters.\nTest (6): Weight.\nThe weight of the children was taken on a balance-scale weighing with an accuracy of one-quarter of a pound. Ordinary in-door clothing was worn.\nTest (7): Height.\nThe Seaver measuring-rod, marked off in both inches and centimeters, was used. It is composed of a straight stick with a sliding arm projecting at right angles. Placing the stick perpendicular to the floor by sighting it parallel with a door-frame, the sliding arm was made to touch the head of the child and then read off in tenths of a centimeter, as marked on the stick. The height was taken with shoes.\nTest (8): Lung-capacity.\nThe Standard wet spirometer was used. This consists of a cylindrical vessel nearly filled with water, through the center of which a tin tube projects, connected at the lower end with a rubber tube through which the experimentee exhales the air. Over this tin tube, projecting in the center of the vessel of water, a tin cylinder, closed at one end, is inverted and allowed to sink in the water by opening a stop-cock at the bottom, letting out the air confined in the vessel by the water. An index finger pointing to a scale on a support on one side, marked off in cubic inches, is fastened to the movable cylinder. As air is blown into the tube the hollow cylinder rises, marking off on the scale the number of cubic inches blown into it. The weight of the tin cylinder is balanced by weights hanging on pulleys above, so that very little pressure is required to raise the cylinder by blowing.\nThe child was told to inhale into its lungs all the air they possibly could contain and then to exhale it through the tube into the spirometer, emptying his lungs as completely as possible. The cubic inches were reduced to cubic centimeters for the final averages of each age.","page":45},{"file":"p0046.txt","language":"en","ocr_en":"46\nJ. A. Gilbert,\nThe beaction-board.\nSince mental tests on children have never been taken to any great extent, there was consequently no suitable apparatus at hand for such tests. The carrying out of my experiments necessitated the construction of what may be called the reaction-hoard, arranged for taking tests (5), (9), (10) and (11). This was constructed on an oak board 33 centimeters square, fig. 5. The main parts are the electro-\nmagnetic tuning-fork A vibrating one hundred times per second, the double-post switch B, the stimulating apparatus C, the reacting-key E, the tapping-apparatus F, the commutator G and the Ewald chronoscope H. The board is raised from the table by four short legs so as to permit insulated wires to pass beneath connecting the different parts of the apparatus through holes piercing the board. One leg d is an adjustable screw by which the board can be fitted to any surface upon which it may be placed. Two separate Gbove batteries had to be used, one connected with the wires I a lb and the other with II\u00ab IB. Current IB IB simply passes through the tuning-fork A, when the bar p of the commutator is left in the position in which the spring naturally holds it, viz: connecting the two posts s and s'. Thus, the tuning-fork is kept in constant motion.","page":46},{"file":"p0047.txt","language":"en","ocr_en":"Mental and physical development of school-children. 47\nThe chronoscope is composed of an electro-magnet with the armature connected with a small lever, one end of which rests against a toothed wheel connected with the finger on the dial visible at H. Every time a current is made to pass through the electro-magnet it draws the lever, thus moving the wheel and the finger on the dial one mark. The circle on the dial of the chronoscope is divided into one hundred parts and thus, if the chronoscope is thrown into a current connecting it with the tuning fork A, which vibrates one hundred times a second, the finger on the dial makes one complete revolution in one second. Every time the fork vibrates the current is made at b by means of an adjustable wire invisible in the figure. Every time this current is made at b the chronoscope moves one mark and thus records the number of vibrations made by the fork, or, in other words, measures in hundredths of a second the length of time a current is allowed to pass through it and the fork. In order to test the chronoscope it was thrown into circuit with a time-marker on a smoked drum according to a method described by Bliss.* 1 To verify results this test was made both before and after the taking of data. The ehronoscope was found accurrate to the error of scale. Owing to the fact that the contact between g and the stimulating rod D is a \u201cmake\u201d contact, an error of 0.005 of a second was introduced, but in' as much as the chronoscope only records in hundredths of a second, this error would not influence the results.\nThe apparatus F which, for my present use, I have called the tapping-apparatus, was at first intended to be used as a habit-key. By unscrewing l and the screws binding the three arms n to the central equilateral triangular plate m, the plate m could be turned to the right thus drawing in toward the center the buttons on the ends of the bars n. The different radii of the circle were measured off on the scale on the face of the board as the index moved to the right or left, according as the imaginary circle, passing through the three buttons on the end of the arms n, was desired smaller or larger. To obtain an expression for habit, the child could be told to tap on the three buttons going in a circle to the right as fast as possible, for five or ten seconds, the number of taps being recorded by the chronoscope. After resting he could then tap the same length of time in the same circle. The increase in number of taps, or percentage of gain, in the second trial over the first, would express the rapidity of forming the muscular habit of moving the hands in a set way. This\n1 Bliss, Researches on reaction-time and attention, Stud. Yale Psych. Lab., 1893\nI 5, fig. 3.","page":47},{"file":"p0048.txt","language":"en","ocr_en":"48\nJ. A. Gilbert,\ntest was given up because it seemed impossible to get the children to keep on going in a circle should they miss one of the buttons; instead, they would almost invariably stop and try to correct their misdirected aim. Although this, however, would make an interesting test on adults, it lay outside of my problem.\nTest (5) : Voluntary motor ability and fatigue.\nBy throwing the arm c of the switch B to the post covered by it when in the position e' the current I a 15 is made to pass through the wire I a across to the reaction-key E, to the binding post g, then through c in position c' to the tapping apparatus F ; thence through the keys n and bars o to the chronoscope H and finally back to the binding post Ib.\nIn measuring voluntary motor ability, the child was asked to tap as rapidly as he could, until told to stop, on the button at the end of the front key n. Closing the key f closed the current at every point except at the platinum contact between the key n and the bar o. Thus, every time the child tapped on the button of key n the contact was made with the bar o allowing tbe current to pass through the electro-magnet of tbe chronoscope, moving the finger on tbe dial one mark. An upright circular screen was fastened to the edge of the dial in order to hide from the child the record made. The child tapped for forty-five seconds. Shortly after he had started tapping, the circuit was closed by pressing down the key / in unison with one of the strokes of a metronome which was adjusted to beat seconds. As soon as the key f was pressed down by myself, the chronoscope commenced recording on its face each tap made by the child. At the end of five seconds I broke the current at / thus cutting off from the chronoscope any means of recording the taps of the child until the current was again made. The child continued tapping simply to produce fatigue. At the end of forty seconds I again made the circuit at f and took a record of the taps made in the last five of the 45 seconds in the same way that the first five were taken. To measure off exactly 5 seconds I counted 0, 1, 2, 3, 4, 5 in unison with the beat of the metronome, pressing down the key / at 0 and releasing it at 5, thus giving an interval of 5 seconds. By this means the control of the 5 seconds was in my own hands; this avoided all such errors as are sure to creep in when the child is simply told to start and stop tapping at word of command, as was done by Bryan in his researches on voluntary motor","page":48},{"file":"p0049.txt","language":"en","ocr_en":"Mental and physical development of school-children. 49\nability.1 In such a case it is very difficult to tell just where the counting of taps should cease, for almost invariably a child adds a stroke or two after being told to stop. By the method used here, however, the tapping is limited to exactly 5 seconds. By throwing the chronoscope into a current with the tuning-fork, vibrating one hundred times per second, I contrived a plan to measure my own accuracy in making and breaking the current at/\u2018in unison with the metronome, leaving exactly 5 seconds intervening. In 5 seconds the hand on the dial of the chronoscope should revolve 5 times. After taking and averaging fifty trials at making a 5-seconds-interval, it was found that my average variation fo\u00e7 a single occasion in making exactly the right length of time was only 0.02 sec. Such an error would be wholly negligible since the highest rate of tapping obtained was 47 taps in 5 seconds. The number of taps made in the first 5 seconds can be taken to represent the voluntary motor ability of the child. It is impossible to tap as rapidly after 45 seconds as at first; by calculating the difference between the two rates of tapping and then dividing this difference by the number of taps made the first 5 seconds, an expression for fatigue was obtained as a per cent. If r be the number of taps for the first 5 seconds and s the number for the last 5 seconds, the degree of fatigue for 40 seconds of tapping can be expressed by\nr\u2014S\nTo have expressed the fatigue merely by the difference between the two rates of tapping would not have expressed the truth ; for instance, one child who tapped 19 and 15 for the respective periods of 5 seconds, lost a great deal more by fatigue than another, who tapped 38 and 34 respectively; each lost 4 taps but the first lost 21 per cent., the second only 11 per cent.\nSince fatigue was the principal problem I had in view in this test, the elbow was held free from the table so as to bring on fatigue the more rapidly. This also would be the most rapid way of tapping, for it consists largely of a movement of the wrist which is one of the most rapid joints for tapping.2\nTest (10): Reaction-time.\nBy throwing the arm c of switch B, fig. 5, to the post covered when in position c\" current I a lb passes, when all points are connec-\n1 Bryan, Voluntary motor ability, Am. Jour. Psych., 1893 Y 14.\n\u25a0 Bryan, Voluntary motor ability, Am. Jour. Psych., 1893 Y 171.","page":49},{"file":"p0050.txt","language":"en","ocr_en":"50\nJ. A. Gilbert,\nted, from the battery through wire la, through the spring e to the end of the rod D, thence through the curved spring to g, thence to and through the arc c of switch B ; thence to key e through binding post k ; thence to r of the commutator through rod p when thrown across from r to r ; thence through the chronoscope, back again to the battery. Current lia IK is connected with the following in succession : lia from battery, binding post a on tuning-fork A ; binding post on the coil of the fork ; s and s' of commutator G, finally, going back to the battery through wire IK. The coil-spring on rod p keeps it continually in connection with the poles s and s', thus keeping current lia IK always closed and the tuning-fork in constant motion, ready for use. Between r and s, r' and s' are two small pieces of hard rubber to insulate and carry the arm easily from ss' to rr'. With the arm I) thrown back by the spring e against the box h the contact is merely broken between the end of the arm D and the curved spring fastened to the brass block g. The child is told to press down the key E as soon as he sees a movement of the disk fastened to the end D. By throwing the rod p of the commutator G upon r and r1, the current la K is closed at every point except where the contact is broken between the arm D and the curved spring on g. By throwing the arm D into the position seen in the figure this contact was made, completing the circuit and at the same time giving the stimulus for reaction. Throwing the commutator into position rr', before throwing the stimulating rod I), served as the warning to the child, that the stimulus would come, as well as changing the current used, from lia IK, which passes through the tuning-fork alone, to the current la K which passes through tuning-fork A, stimulating rod D, reacting key E and chronoscope H. As soon as contact was made at g, by throwing the stimulating rod I), the current, being made and passing through tuning-fork A, which is vibrating 100 times per second, started the chronoscope going at the rate of 100 marks or one revolution per second. As soon as the break-circuit key E is pressed, the current is immediately broken ; thus stopping the chronoscope. This records the number of hundredths of a second which elapsed between the movement of rod D by myself and the pressing of the key E by the child. After the reaction, the key E is grasped and held down by a small spring x until the record can be read from the ehronoscope and recorded. Spring e also throws the rod D back into its original position, breaking the contact at the spring on g as before. After a record is made on the card of the number of hundredths of a second it took the child","page":50},{"file":"p0051.txt","language":"en","ocr_en":"Mental and physical development of school-children. 51\nto react, the spring x is loosened by pushing it off the key E by the rodj and the finger of the chronoscope is moved back to 0 ready for the next test. Each child was given ten trials, the median value of which was taken for his reaction-time. In order to prevent the child anticipating the moment when the stimulating rod D is to be thrown by seeing the hand move, a screen extended back over my hand and the apparatus about the part e, f and g. This screen has been removed in the figure so as to exhibit the keys e, f and g. The face of the chronoscope H was also hidden from the child by a small semi-circular screen fastened to its edge. The Ewald chronoscope,1 as seen in the figure, is taken from its usual stand and fastened to the board so as to place it near the commutator, thus allowing it and the commutator to be manipulated conveniently with the left hand.\nTest (9) : Reaction with discrimination and choice.\nThe apparatus for this test was the same as in simple reaction with the addition of the color apparatus h with rod i. Fastened to the rod i and concealed in the box A is a slide nearly as wide as the box but only two-thirds as long. Upon this slide are glued two pieces of colored paper, red and blue, each taking up one-half of the slide. By pushing in the rod i till it strikes at the end of the box at C, blue is exposed at the opening in the top, while red is concealed under the top of the box between the opening and the end marked G. By pulling out the rod * till it strikes the other end of the box h, red is exposed. The exposure is made when the stimulating rod D is thrown into the position seen in the figure. The child was told to react on the key E if the color, when exposed, was blue, and not to react if it was red ; this compelled him to wait and discriminate between red and blue and also to make the choice whether to react or not. First, the bar p of the commutator G is thrown from current ss' to rr', serving also as a warning to the child that the stimulating rod Z> will soon be thrown aside. The rod D is then thrown, whereby the chronoscope is started. Pressure on the key E immediately stops the chronoscope while the spring x also holds down the key E until the number of hundredths of a second, counted off by the chronoscope,. can be recorded on the record-card. After moving the finger of the chronoscope back to 0 by a wheel invisible in the figure and releasing the spring x by pushing rod j, the apparatus is ready for the second test, the commutator p having been brought back to ss\u2019\n1 Dumreichbb, Zur Messung der Reactionszeit, Inaug. Diss. Strassburg 1889.","page":51},{"file":"p0052.txt","language":"en","ocr_en":"52\nJ. A. Gilbert,\nagain by the spring attached to it. That part of the rod i which is not concealed by the screen over the hand and keys e,f and g, is concealed by a wooden covering so as to prevent the child from knowing by the position of the rod what color will appear. For reasons mentioned below this test preceded that for reaction-time.\nTest (11) : Time-memory.\nThe same apparatus on the board was used here as in the preceding test, except that instead of using the stimulating rod D to start the chronoscope, the key/was used. The chronoscope, when in motion at the rate of one hundred marks a second, makes the same tone as the fork only somewhat louder and of different timbre. The tuning-fork is mounted on hair-felt so as to muffle its sound, leaving the sound of the chronoscope very easily heard. The child was told to listen how long I caused the chronoscope to sound and then after I started the sound the second time he was to stop it by pressing down the key E when he thought it had gone just as long as I allowed it to go the first time. After throwing the commutator from ss' to rr to change currents and also to warn the child that the sound would soon begin, the current was made by pressing down the key / which was held down till the finger on the dial of the chronoscope H had made two complete revolutions, whereupon it was released ; thus the sound continued for two seconds. The shade concealing the dial kept the record from being seen. Almost immediately after the current was broken, it was again made at /. This again started the sound which continued until the child stopped it by pressing down the key E. The key was held down as before by the self-catching spring x until the record on the chronoscope could be read and recorded. The figures entered on the card represented the error, in hundredths of a second, made by the child in trying to make the second sound just as long as the first. As it was impossible for me to make the standard exactly two seconds, this error, never more than 0.05 of a second, was added to or subtracted from the error of the child according to its direction. Each child was given ten trials from which the median value was calculated for his general result.\n\u2019\tGeneral methods.\nTests on muscle-sense, color-sensitiveness and force of suggestion were not taken simultaneously with the other tests. In taking the tests on voluntary motor ability, fatigue, weight, height, lung-capacity, discrimiuation-time, reaction-time and time-memory the","page":52},{"file":"p0053.txt","language":"en","ocr_en":"Mental and physical development of school-children. 53\nfollowing order was adopted. Three children were taken from the school-room at one time into a secluded room away from interruption, noise, etc. While one was taking the tests the other two could be watching and thus, when their turns came, they understood what was expected of them, and took but little time for explanations. Furthermore, when their turns came the novelty of the board and tests was worn away, so that their whole attention could be devoted to doing the things required. The child was first weighed, his height was taken next and then his lung-capacity was measured. After this he was subjected to the tests of the reaction-board, the first being discrimination-time for red and blue. This test was given precedence in time to simple reaction because after getting accustomed to reacting every time the stimulating rod was moved, as is the case in the simple reaction, it is very much more difficult to refrain from pressing reflexly or automatically when the red is exposed in the discrimination-test than if the latter is placed first. In this test the number of errors made by pressing the key E when red was exposed, instead of not pressing at all, was kept account of. The red and blue were exchanged irregularly so that the child could get no idea of what color to expect. So as to put him more thoroughly on his guard, several reds were generally exposed at the start. Ten trials were given in this and in the two succeeding tests, the result of each trial being recorded in its proper place on the card as soon as taken. Reaction-time was taken next, and then the test on time-memory. Finally, after all other tests had been taken (which required from seven to ten minutes) the tests on voluntary motor-ability and fatigue were taken. During the 35 seconds interval between the first and last period of five seconds of the forty-five seconds of tapping, the next child\u2019s weight and height were taken. When the child at the board had completed the fatigue-test he was sent back to the room and immediately another came to fill his place, thus keeping three out at onetime. Just before taking the reaction-board-tests on the child the day of the month and the hour of the day were noted after \u201c date \u201d on his card so as to enable me to calculate at some future time the effects of weather and also of fatigue produced by the day\u2019s work upon those tested late in the day, compared with those taken early in the morning, The teachers attended to having the remainder of the data filled out at the head of the card, in regard to the child, namely, age at last birthday, birth-place, birthplace of father, birth-place of mother, father\u2019s occupation. White cards were used for girls and colored cards for boys.","page":53},{"file":"p0054.txt","language":"en","ocr_en":"54\nJ. A. Gilbert,\nResults..\nAbout one hundred children of each age were taken, the small variation from this number being shown in column N of the tables I to XI. The method explained* above necessitated tests one to three inclusive being taken at a different time from the remainder. Some of the children, having taken one portion of the tests, were absent at the time the other tests were taken, thus causing the number to fall slightly below one hundred in some instances. The results for each age were averaged into one final result by taking the median\nTb + 1\t\u2022\nvalue1 according to the formula\u2014\u2014. The justifiableness of this\nmethod will be shown later both by data and curves.\nFechner has proposed the use of the median or central value, whose position in the series of separate results arranged according\n9b 1\nto size is given by ------. That is, if all the results are to be ar-\nranged in the order of their size, the median will be just in the middle. Since with finite units of measurements there will be a number of results having the same value around the middle, the value will be determined by interpolation. The importance of the use of the median lies in the fact that it involves no assumption in regard to the distribution of the separate deviations.\nIn order to get an expression for the homogeneity of my results the mean variation was calculated for each age. This same calculation was also made for boys and girls separately in all the tests except the first three, viz : muscle-sense, color-sensitiveness and force of suggestion. After the record-cards were completely filled out with the data desired, they were returned to the teachers of the respective rooms, who were asked to mark each name by a figure 1, 2 or 3 according to what she judged the child\u2019s general mental ability to be, marking the bright ones 1, those of average ability 2 and the dull ones with a figure 3. The aim of this was to get the relation between the general mental ability and the respective tests. The tests were taken from January 17th to April 1st, 1894.\nTest (1): Muscle-sense.\nThe results for this test are shown in table I and the accompanying charts I and II, giving in graphic form the results as given in columns D, 11, G and MVof the table. Sensitiveness to weight\n1 Scripture, On the adjustment of simple psychological measurements, Psych. Bev., 1894 1 281.","page":54},{"file":"p0055.txt","language":"en","ocr_en":"Mental and physical development of school-children. 55\nwas riot so delicate as was supposed when the apparatus was made, and consequently a series of ten weights varying two grams each, from 82\u00ab to 100\u00ab, was insufficient to include all of the younger children. In all ages, except fourteen and fifteen, one or more children were found whose sensitiveness to weight-differences did not fall within the scope of my apparatus, viz. 18\u00ab variance from the standard weighing 82\u00ab. In calculating column D of table I, all data including those in which all ten were said to be alike in weight were used. In order to correct this error of apparatus, the per cent, of data in which all ten weights were reported as being alike was calculated for each age. To obtain a correct estimate of the discrimination to weight for each age, the columns D and P must be considered together ; that is, the results for this sense give the wrong impression, unless both of the columns be considered in conjunction. The figures at the left of the chart indicate the threshold for discrimination to weight in grams. The figures found in columns P, PB and PG of table I represent in per cent, the number of children who picked out all ten weights as being exactly alike, distinguishing no difference whatever in their respective weights. It will be remembered that sensitiveness varies inversely as the size of the least perceptible difference. For example, the least perceptible differences for the ages 6 and 7 are 14.8\u00ab and 13.6\u00ab respectively ; the threshold for 6 yrs. bears to that for 7 yrs. the relation -J-f-g-, but the sensitiveness for 6 yrs. is greater than that for 7 yrs., the relation being\tIn general it is convenient to indicate the sensitiveness\nby the reciprocal of the least perceptible difference, thus, T\\-g, TiF, etc. On the chart, the higher the line the greater the least perceptible difference but the smaller the sensitiveness. Ages are marked along the axis of abscissas at the bottom of the chart.\nThe results show a gradual increase in ability to discriminate, from the ages of 6 to 13. At 6, the worst year of any for discrimination, the least perceptible difference was 14.8\u00ab, with 38$ of non-discriminations ; at 13 years only 5.4\u00ab with 2$ of non-discriminations. After 13 there was a gradual falling off of 6.8\u00ab, none failing to discriminate, and then another gain till at 17 it was 5.8\u00ab with 1$ of non-discriminations. Boys and girls, considered together, gradually increase in ability, but when they are considered separately, marked differences of sex appear. At 6 there is the large difference of 3.8\u00ab in discriminative ability in favor of the boys. At 7 they have the same ability. From this on, they gain with equal pace to the year 13 with the exception of the abrupt falling off for boys at 11. From 13 to 17","page":55},{"file":"p0056.txt","language":"en","ocr_en":"56\nJ. A, Gilbert,\nthe difference in ability again becomes manifest in favor of boys. In general it may be said that the superiority of boys in sensitiveness to differences in weight increases with age, irregularities being noticeable, however, from 6 to 7 and from 12 to 14.\nIt is interesting in this connection to notice the relation between the general curve, chart I, and the curve of mean variation for the same test, chart II. There seems to be a general agreement throughout between the main curve for discrimination and the curve for\nTable I.\nMuscle-sense.\nAge.\tD\tP\tMV\tB\tPB\tG\tPG\tN\tNB\tNG\n6\t14.8\t38\t5.2\t13.0\t26\t16.8\t49\t87\t42\t45\n7\t13.6\t36\t4.4\t13.2\t36\t13.2\t40\t92\t50\t42\n8\t11.4\t30\t4.6\t12.2\t35\t11.0\t28\t92\t46\t46\n9\t10.0\t20\t4.4\t10.2\t23\t10.0\t17\t95\t48\t\u202247\n10\t8.8\t12\t4.4\t8.6\t12\t9.2\t12\t91\t49\t42\n11\t8.6\t6\t3.8\t10.2\t5\t7.6\t6\t89\t42\t47\n12\t7.2\t3\t3.0\t7.6\t0\t7.6\t6\t101\t53\t48\n13\t5.4\t2\t3.0\t6 0\t5\t5.6\t0\t102\t44\t58\n14\t'5.6\t0\t3.0\t5.2\t0\t7.2\t0\t100\t47\t53\n15\t6.8\t0\t2.2\t6.2\t0\t7.2\t0\t100\t49\t51\n16\t6.6\t1\t2.4\t6.0\t2\t6.8\t2\t87\t48\t39\n17\t5.8\t1\t2.6\t6.0\t0\t6.4\t2\t91\t47\t44\nD, least perceptible difference in grams. G, least perceptible difference for girls. P, per cent, of data showing no discrim- PG, per cent, of girls showing no dis-\nination.\ncrimination.\nMV, statistical mean variation.\nB, least perceptible difference for boys. PB, per cent, of boys showing no dis-\nN, number of children, NB. number of boys. NG, number of girls.\ncrimination.\nmean variation. When discriminative ability decreases, between any two successive ages, the variation decreases for the corresponding period. On the whole, however, variation decreases with advance in age. At the age of 7, where a falling off in sensitiveness is indicated in the main curve for discrimination, the mean variation is decreased. Also during the years from 12 to 14 the variation is stationary, these too, being years during which the child lost in his ability to discriminate, as shown by chart I. Apparently during these years development has been arrested and consequently those influences removed which would cause variation in the results of different children. At 15, when the discrimination was relatively poor, the mean variation was very small.","page":56},{"file":"p0057.txt","language":"en","ocr_en":"Mental and physical development of school-children.\n57\nIn such points the mean variation throws some light upon those years where divergences and abrupt changes occur. Marked changes in the curve for variation would indicate unusual heterogeneity in data at that point. Such results unquestionably represent changes in growth.\nFig. 6. Chart I.\nBoys and girls.\nTest (2) : Sensitiveness to color-differences.\nThe results of this test are recorded in table II and charts III and IY. The same general rules apply here as in the results of the previous test. The two columns D and P of table II have to be con-","page":57},{"file":"p0058.txt","language":"en","ocr_en":"58\nJ. A. Gilbert,\nsidered in conjunction, because the scale of shades was insufficient to admit of discrimination of difference in color by all children. As in the previous test the figures in column P, PS and PG indicate the per cent, of children of the respective ages, who said all the colors were exactly alike, discriminating no difference in shade. The numbers on the left, by which the solid line is to be interpreted, indicate the number of colors picked out as being exactly alike. The ages are indicated at the bottom of the chart on the axis of abscissas. Ability to distinguish different shades of the same color increases with age. As a rule, at 1 marked irregularities occur in all the curves which require mental action or discrimination. These irregularities will be spoken of more fully later on.\nTable II.\nSensitiveness to color-differences.\nAge.\tI)\tP\tMV\tB\tPB\tG\tPG\tN\tNB\tNG\n6\t9.6\t57\t1.8\t8.3\t51\t9.6\t62\t90\t45\t45\n7\t9.0\t49\t2.1\t8.3\t48\t9.6\t50\t94\t50\t44\n8\t8.3\t44 \u25a0\t2 3\t9.6\t51\t7.0\t39\t90\t44\t46\n9\t6.3\t23\t2.2\t6.1\t24\t6.6\t22\t95\t45\t50\n10\t6.4\t11\t1.9\t6.0\t16\t5.2\t5\t91\t48\t43\n11\t5.4\t4\t1.7\t6.0\t9\t4.9\t0\t89\t41\t48\n12\t5.1\t3\t1.5\t4.8\t2 .\t5.1\t4\t101\t53\t48\n13\t4.6\t4\t1.7\t5.2\t9\t4.1\t0\t102\t44\t58\n14\t4.7\t3\t1.4\t4.8\t7\t4.6\t0\t101\t47\t54\n15\t4.4\t1\t1.1\t4.1\t0\t4.6\t2\t100\t49\t51\n16\t4.3\t1\t1.3\t4.3\t0\t4.0\t2\t87\t48\t39\n17\t3.9\t3\t1.4\t4.0\t6\t4.9\t1\t91\t47\t44\nB, least perceptible difference in color in number of shades.\nP, per cent, of data showing no discrimination.\nM, statistical mean variation.\nB, least perceptible difference for boys.\nPB, per cent, of data of boys showing no discrimination.\nIn this test the advantage is slightly in favor of the girls. The curves cross and re-cross so frequently, however, that no very plain statement as to comparison of sexes can be given. The boys start at 6 with the advantage of the girls, but at IV the girls take the lead. By making a general average of all ages for all the boys and all the girls, the advantage of girls over boys is only one-tenth of the difference between the successive shades. Yet, girls have the additional\nG, least perceptible difference for girls. PG, per cent of data of girls showing no discrimination.\nN, number of children.\nNB, number of boys.\nNG, number of girls.","page":58},{"file":"p0059.txt","language":"en","ocr_en":"Mental and physical development of school-children.\n59\nadvantage in that only 18.1$ of the girls failed to discriminate at all, while 22.3 $ of the boys failed in so doing. This throws the final balance somewhat in favor of the girls. The curve of this sense,\nFig. 8. Chart III.\n----\u2014 Boys and girls.\n.....Boys.\n------Girls.\nFig. 9. Chart IV. Statistical mean variation.\nchart II, shows the most gradual increase in discriminative ability of any worked out and it will also be noted that the same general regularity in decrease of variation is shown in chart IY, with a slight divergence at 13, due probably to puberty.\nTest (3) : Force of suggestion.\nWe are continually translating sensations gained from one sense into terms of another sense. In walking, or reaching for articles in the dark, we always imagine how things ought to look and then translate these ideas of sight into muscle sensations in guiding our","page":59},{"file":"p0060.txt","language":"en","ocr_en":"60\nJ. A. Gilbert,\nmuscles. In reaching for the door-knob with closed eyes one always guides his hand by translating how the extended hand looks into how it should feel. The experiments of this test were taken with a view to measuring the influence of the interpretation given by one sense on the decision of another sense, the result being expressed as a function of the age.\nThe results obtained are recorded in table III and charts V and VI. In considering the results, columns D and P, B and PB, G and PG of table II have to be taken together as in the two preced-\nTable III.\nForce of suggestion.\nAge.\tH\tP\tMV\tB\tPB\tG\tPG\tN\tNB\tNG\n6\t42.0\t36\t17.0\t43.5\t37\t42.5\t36\t92\t45\t47\nI\t45.0\t37\t15.5\t43.5\t35\t43.5\t39\t95\t50\t45\n8\t47.5\t27\t13.5\t45.0\t27\t49.5\t36\t92\t46\t46\n9\t50 0\t36\t10.5\t50.0\t38\t49.5\t35\t94\t47\t47\n10\t43.5\t23\t12.5\t40.0\t18\t44.0\t27\t91\t49\t42\n11\t40.0\t22\t11.5\t38.5\t11\t40.0\t14\t91\t43\t48\n12\t40.5\t15\t9.0\t38 0\t12\t41.0\t18\t103\t54\t49\n13\t38.0\t8\t9.0\t37.0\t8\t38.0\t9\t103\t45\t58\n14\t34.5\t7\t9.5\t31.0\t8\t33.5\t2 \u2019\t100\t47\t53\n15\t35.0\t12\t10.5\t33.0\t2\t38.0\t20\t100\t49\t51\n16\t34.5\t6\t10.0\t32.0\t5\t38.5\t7\t86\t47\t39\n17\t27.0\t5\t12.0\t25.0\t1\t31.0\t10\t84\t43\t41\nH, force of suggestion, in grams.\nP, per cent, of data in which the force of suggestion exceeded 65 grams.\nMV, statistical mean variation.\nB, force of suggestion for boys, in grams. PB. per cent, of data for boys in which the force of suggestion exceeds 65 grams.\nG, force of suggestion for girls, in grams. PG, per cent, of data for girls in which the force of suggestion exceeded 65 grams. N, number of children.\nNB, number of boys.\nNG, number of girls.\ning tests. The figures of columns P, PB and PG of table III indicate the per cent, of data in which the extremes'of the series of fourteen blocks were picked out as of the same weight as the respective standards to be compared. The figures at the left of the chart indicate in grams the amount of error made in estimating the differences in weight between the large and small blocks. Ages are marked at the bottom of the chart. As explained under apparatus for test (3), the large and small blocks were both exactly alike in weight, but, owing to the difference in size, the child\u2019s judgment as to what the","page":60},{"file":"p0061.txt","language":"en","ocr_en":"Mental and physical development of school-children.\n61\nblocks should weigh by muscle-sense was so influenced by the suggestion from the eye as to what their relative weight should be if judged from sight, that e. g. at 6 they thought there was a difference of 42\u00ab between them. In addition to this, in 30$ of the data more difference was made between them than could be measured by the limits of my\nFig. 10. Chart V.\n-------Boys and girls.\n______ Boys.\n-------Girls.\nFig. 11. Chart VI. Statistical mean variation.\nfourteen weights, viz : 65\u00ab. At 7 they were influenced by the suggestion of sight even more than at 6. At 7 they made a difference of 45\u00ab between the blocks while 37$ said there was more difference in their respective weights than my weights would measure, viz : 65\u00ab. The influence of the suggestion gradually increased, reaching its maximum at 9 where the average child thought there was a difference of 50\u00ab which is almost as much as the weight of the blocks themselves, viz: 55\u00ab. In addition to this, at 7, still 36$ judged the difference larger than 65\u00ab which was the limit of my test. From 3 to 17 this influence gradually decreased, the muscle-sense gradually","page":61},{"file":"p0062.txt","language":"en","ocr_en":"62\nJ. A. Gilbert,\nlearning to correct the suggestion given by sight as to what the relative weight should be. At 17 the large difference of 27g in weight was made between the two blocks while still 5$ were found whose error of judgment fell beyond the limits of measurement. As seen in columns B, PB, G and PG of table III and also as seen incurves on chart Y a marked difference may be noted between boys and girls. Boys, being influenced more by the suggestion, are slightly worse at 6 than girls ; at 7 both are equal ; but thereafter girls are considerably worse than boys with one exception at 9, where the girls and boys may again be said to be the same since the difference is only one-half a gram. The deflection of the curve at age 14 from its general trend is again noticeable, that of the girls being most marked. It is to be presumed that the child grows worse from 6 to 9 because at 6 he has not yet learned to compare, and that as he learns gradually to judge of a thing from more aspects than one, or, in other words, learns to interpret one sense by another, the force of the suggestion given by the eye to the muscle increases until at 9 he has come to the age of experience enough to see that things are not always what they seem. Consequently at this age he begins to correct misleading influences bearing upon him. This error can never be wholly eliminated, for in all my experiments on old as well as young, I have found no one who was not subject to the illusion. The small one was universally chosen as the heavier of the two and not infrequently was it judged to be more than twice as heavy, even by adults. All those who judged that there was more difference in weight between the two blocks than 65*\u2014the limit of my test\u2014it will be easily seen, made the smaller one more than five times as heavy as the larger one. Reference to column P, table III, age 7, shows that at that age 37$ gave the judgment that the large one weighed 15* or less while the small one weighed 80* or more. Since 15* and 80* were the lightest and heaviest blocks respectively in my series of fourteen, and, since so many picked out these two extremes, it is highly probable that quite a number would have made a much greater difference than 65* between the weights.\nThe blocks, of course, are seen before being lifted and immediately upon seeing them one judges by sight that the larger one ought to be much the heavier. However, upon lifting and receiving about the same sensation in weight from both we are immediately led to reverse our decision and judge the smaller one to be the heavier.","page":62},{"file":"p0063.txt","language":"en","ocr_en":"Mental and physical development of school-children. 63\nOn the whole, variation decreases with advance in age. In the main carve, chart V, the child becomes worse in his judgment from 6 to 9. In variation, chart VI, he becomes better. In the main curve at 9 he becomes better. In variation curve he becomes worse. At ten the variation again becomes subject to the more general law, however, of decrease with age. The particular law, however, that for short periods in the development where ability increases variation increases, is substantiated by a large proportion of cases in each curve which represent a larger proportion of mental activity.\nTest (4) : Voluntary motor ability.\nIn column T of table IV are recorded the number of taps the average child can make in five seconds for the respective ages. The results are given in graphic form in charts VII and VIII. The ages are marked along the axis of abscissas, and the figures to the left along the axis of ordinates represent the number of taps made in five seconds. B and G of the same table are the averages for boys and girls respectively. The average child at 6 years taps 20.8 times in five seconds. From 6 there is a gradual increase until the age 12, reaching at that age a rapidity of 29.9 taps in five seconds. At 13, however, this is lowered to 28.9 taps in five seconds. From this there is the gradual increase again, reaching the maximum at 17 with a rate of tapping amounting to 33.8 taps in five seconds. The data, when calculated for boys and girls separately, show throughout a higher rate of tapping for boys than for girls. Boys at 6 tap 21 times while girls tap only 19.7 times in the five seconds. As the increase in ability goes on, boys always excel in about the same proportion except at 14 and 17 where the difference is much more apparent.1 2 Both fall off considerably from 12 to 13. At thirteen however, the boys regain their lost footing and begin to increase again as rapidly as they did before 12. The girls, however, continue to lose until 14 before beginning to gain again. From 16 to 17 they fall off once more. The divergence in this as well as the preceding curves at the period from 12 to 14 is undoubtedly due to the effects of puberty. This would contradict somewhat the statement of Bubnham\u20191 who says that at puberty there is a great increase of\n1\tBryan, On the development of voluntary motor ability, Am. Jour. Psych., 1893 Y 173.\n2\tBurnham, The study of adolescence, Ped. Sem., 1892 I 181.\n","page":63},{"file":"p0064.txt","language":"en","ocr_en":"64\nJ. A. Gilbert.\nvitality and energy and also greater mental activity. The former is undoubtedly true but whether the latter is a justifiable conclusion therefrom is very doubtful. My curves throughout rather seem to justify the opinion of Lange1 * that physical development takes up the strength and thus retards the mental development.\nTable IV.\nVoluntary motor ability.\nAge.\tT\tMV\tB\tMV'\tG\tMV\"\tN\tNB\tNG\n6\t20.8\t2.4\t21.0\t2.5\t19.7\t2.5\t98\t49\t49\n1\t22.5\t2.9\t22.8\t2.7\t21.2\t2.5\t98\t60\t48\n8\t24.4\t2.9\t24.9\t3.4\t23.9\t2.2\t96\t49\t47\n9\t25.4\t2.5\t25.8\t2.5\t25.0\t2.9\t99\t60\t49\n10\t27.0\t2.8\t27.7\t2.6\t26.9\t2.8\t97\t60\t47\n11\t29.0\t3.3\t29.7\t3.2\t27.8\t3.0\t101\t50\t61\n12\t29.9\t3.3\t30.3\t3.1\t29.6\t3.0\t106\t56\t50\n13\t28.9\t2.8\t29.8\t3.0\t28.1\t3.3\t110\t59\t51\n14\t30.0\t3.6\t31.2\t3.2\t28.0\t3.4\t104\t50\t54\n15\t31.1\t3.0\t31.3\t2.6\t29.8\t3.2\t101\t51\t50\n16\t32.1\t3.3\t33.0\t3.0\t31.8\t3.4\t87\t48\t39\nIT\t33.8\t2.9\t35.0\t2.4\t31.5\t2.3\t91\t47\t44\nT, number of taps in five seconds.\nMV, statistical mean variation.\nB, number of taps for boys.\nMV', statistical mean variation for boys. G, number of taps for girls.\nMV\", statistical mean variation for girls. N, number of children.\nNB, number of boys.\nNG, number of girls.\nHowever that may be, for some cause or other, the children must have labored under some disadvantage in almost all my tests at the period about 13. Bryan\u2019s children3 * * * labored under some similar difficulty at about 13. The individual rate of tapping varied from 14 taps in five seconds by a couple of children 6 years old to 45 taps in five seconds by a boy 17 years of age.8 The average variations for each age can be seen by referring to table IY and chart VIII.\n1 Lange, Uber eine h\u00e4ufig vorkommende Ursache von der langsamen und mangelhaften geistigen Entwicklung der Kinder, Zt. Psych. Phys. Sinn., 1893 VII 95.\n1 Am. Jour. Psych. 1893 V 204 charts I to V.\n3 Ko set amplitude of movement was given, thus allowing the child to choose that\nbest adapted to rapidity for himself. Amplitude of movement, however, makes no\nspecial difference in rapidity ; cf. Bryan, Voluntary motor ability, Am. Jour. Psych.,\n1893 V 150, 116.","page":64},{"file":"p0065.txt","language":"en","ocr_en":"Mental and physical development of school-children.\n65\nFig. 12. Chart VII.\n------Boys and girls.\n......Boys.\n------Girls.\nFig. 13. Chart VIII.\nStatistical mean variation. Statistical mean variation for boys. Statistical mean variation for girls.\nThe mean variations for the total result of hoys and girls combined were calculated as well as for boys and girls separately, and are found recorded in columns MV, MV' and MV\" respectively. A graphic presentation of the same is also given in chart VIII.\n5\n*","page":65},{"file":"p0066.txt","language":"en","ocr_en":"66\nJ, A. Gilbert,\nTsst (5): Fatigue.\nj^.fter tapping for 45 seconds fatigue entered into the results very noticeably. Column F of table V gives the per cent, of loss between the rapidity of tapping for the first 5 and that for the last 5 of 45 seconds. Columns B and G give the same calculation for boys and girls respectively. MV denotes the amount of deviation of each result from the general average while MV and MV\" indicate the same for boys and girls respectively. The same results are to be\nAge\tF\tMV\tB\tTable V. Fatigue. MV\tG\t\tMV\"\tN\tNB\tNG\n6\t21.4\t8.1\t22.8\t9.4\t21.3\t7.0\t98\t49\t49\n7\t21.0\t8.9\t22.5\t9.7\t20.2\t6.7\t98\t50\t48\n8\t24.0\t7.3\t24.7\t8.3\t23.3\t7.1\t96\t49\t47\n9\t21.0\t7.1\t22.5\t6.7\t20.7\t7.8\t99\t50\t49\n10\t22.0\t7.5\t22.7\t7.8\t19.0\t7.1\t97\t50\t47\n11\t20.0\t6.2\t20.3\t6.5\t18.0\t5.5\t101\t50\t51\n12\t16.0\t6.3\t18.0\t6.0\t14.0\t6.7\t106\t56\t50\n13\t14.5\t6.4\t15.8\t6.7\t14.7\t5.8\t110\t59\t51\n14\t14.0\t6.5\t17.8\t6.2\t12.0\t6.1\t104\t50\t54\n15\t12.7\t5.8\t13.8\t4.9\t11.5\t5.7\t101\t51\t50\n16\t14.7\t5.2\t15.3\t4.6\t11.7\t5.6\t87\t48\t39\n17\t13.8\t5.3\t14.5\t6.3\t13.5\t4.3\t91\t47\t44\nF, per cent, of loss in rapidity of tapping after tapping 45 seconds.\nMV, statistical mean variation.\nB, per cent, of loss in rapidity for boys. MV, statistical mean variation for boys.\nG, per cent, of loss in rapidity for girls. MV\", statistical mean variation for girls. N, number of children.\nNB, number of boys.\nNG, number of girls.\nfound in graphic form in charts IX and X. Ages are marked at the bottom. The figures to the left of the chart indicate the per c\u00e9nt. of loss in rapidity of tapping between that of the first five and that of the last five seconds. The average child at 6 loses 21.4$ after tapping 45 seconds. From 6 to V a slight gain is made, the loss by fatigue being 21$ at '7. At 8, however, the effect of fatigue is much more marked, this being the age at which the child loses most rapidly ; here there was a loss of 24$. After 8 the fatigue is less and less noticeable till the age of 15 where it was least marked, being only 12.7$. From 15 to 16 it again becomes more marked, a loss of 14.7$ occurring at 16 with a succeeding gain again at 17, where it was 13.8$.\nWhen these data are calculated for boys and girls separately, it becomes evident that girls tire more easily at 13 than at 12 while","page":66},{"file":"p0067.txt","language":"en","ocr_en":"Mental and physical development of school-children. 67\nFig. 14. Chart IX.\nBoys and girls.\n\u2014 Girls.\nFig. 15. Chart X.\nStatistical mean variation. Statistical mean variation for Boys. Statistical mean variation for girls.\nfor boys this variance comes a year later between 13 and 14. As in almost all of the charts representing mental research, there seems","page":67},{"file":"p0068.txt","language":"en","ocr_en":"68\nJ. A. Gilbert,\nto be a marked turn in tbe life of the child at 7. This divergence is brought out very plainly also by the mean variations shown in chart X for ages 6 and 7.\nBoys tire more quickly throughout in voluntary movement than girls. But the statement that boys tire more easily than girls could scarcely be made upon the basis of my data for it will be remembered that the rate of tapping by the boys, as shown by table IV and chart VII, was faster than that by the girls. The statement that boys tire more easily is unwarrantable, for, by averaging and comparing the rate of tapping for all boys and girls separately, it is found that the girls on the whole1 tap slower than the boys who lose but little more than the girls by fatigue, leaving the balance in favor of boys. The average boy, including all ages, taps 29.4 times in five seconds, the average girl taps 26.9 times, thus tapping 8.5$ slower than boys. The average boy, including all ages, loses 18.1$ by fatigue; the average girl loses 16.6$. In other words, the boys lose 1.5$ more by fatigue than girls and yet boys tap 8.5$ faster than girls. This leaves the balance greatly in favor of boys when voluntary motor ability and fatigue are considered together.\nTest (6): Weight.\nColumn W of table VI indicates the weight in pounds according\n\t\t\t\tTable YI.\t\t\t\t\t\t\t\t\n\t\t\t\tWeight.\t\t\t\t\t\t\t\t\nAge. W\tMV\tB\tMV\tG\tMV\"\t\tA\tB\tC\tN\tNB\tNG\n6\t46.0\t4.6\t46.8\t4.4\t44.3\t4.3\t\t43.3\t46.8\t49.0\t98\t50\t48\n7\t51.0\t4.8\t51.2\t4.7\t50.4\t4.4\t\t48.3\t51.0\t51.5\t98\t50\t48\n8\t53.0\t5.9\t52.5\t6.0\t53.0\tc.l\t\t53.3\t53.5\t53.3\t96\t49\t47\n9\t59.5\t6.2\t60.0\t9.9\t58.8\t6.8\t\t59.0\t59.0\t61.5\t97\t49\t48\n10\t66.5\t7.7\t68.4\t\u2022 6.9\t62.7\t7.4\t\t67.2\t64.5\t66.8\t96\t60\t46\n11\t70.0\t7.8\t70.8\t6.7\t70.0\t6.0\t\t70.0\t70.0\t66.5\t101\t51\t50\n12\t83.5\t12.3\t82.3\t6.7\t84.5\t11.5\t\t83.0\t83.3\t87.8\t106\t56\t50\n13\t89.5\t11.6\t88.0\t9.4\t92.0\t10.6\t\t82.2\t92.3\t86.0\t110\t59\t51\n14\t96.0\t15.4\t91.7\t15.8\t98.0\t13.3\t\t98.5\t98.8\t90.3\t104\t50\t64\n15\t105.0\t13.7\t110.0\t15.4\t104.0\t10.5\t\t105.5\t106.0\t105.0\t102\t51\t51\n16\t119.8\t15.4\t127.0\t11.9\t113.0\t11.7\t\t116.0\t124.5\t118.3\t87\t48\t39\n17\t122.0\t14.9\t130.0\t11.3\t113.7\t15.1\t\t120.0\t122.8\t125.0\t90\t46\t44\nW, weight\tin pounds.\t\t\t\t\tA, weight of bright children.\t\t\t\t\t\t\nMV. statistical mean variation.\t\t\t\t\t\tB, weight of average children.\t\t\t\t\t\t\nB, weight of boys.\t\t\t\t\t\tO, weight of dull children.\t\t\t\t\t\t\nMV, statistical mean variation for boys.\t\t\t\t\t\tN, number of children.\t\t\t\t\t\t\nG, weight of girls.\t\t\t\t\t\tNB, nutnber of boys.\t\t\t\t\t\t\nMV\", statistical mean variation for girls.\t\t\t\t\t\tMG, number of girls.\t\t\t\t\t\t","page":68},{"file":"p0069.txt","language":"en","ocr_en":"Mental and physical development of school-children.\n69\nFig. 18. Chart XI.\nBoys and girls.\nGirls.\nFig. 17. Chart XII.\nStatistical mean variations. Statistical mean variation for boys. Statistical mean variation for girls.","page":69},{"file":"p0070.txt","language":"en","ocr_en":"70\nJ. A. Gilbert,\nto age. The individual weights were taken in quarter-pounds. The , weights of boys and girls separately are to be found in columns B and G. In chart XI the ages are at the bottom and the weight in pounds to the left of the chart. The figures at the left of chart XII indicate the variation in pounds. The average weight at 6 years was 46 pounds; this in general increases with advance in age, the weight at 17 being 122 pounds. Certain differences are noticeable in the relative rapidity of growth between different ages. Boys have their most rapid growth between 14 and 16, increasing in weight 18.3 pounds between 14 and 15, and 17 pounds between 15 and 16, but between 16 and 17 the increase in weight is very slight indeed, being only 3 pounds. The most rapid growth for girls occurs between 11 and 12, being 14.5 pounds. Up to the age 12 boys and girls seem to grow in about the same proportions, boys being slightly heavier than girls. Between 11 and 12 the order is reversed, girls growing faster and becoming heavier than boys ; they remain heavier until between 14 and 15. Between 14 and 15 boys again begin very rapid growth and from then on are much heavier than girls.\nAt the age 11, as shown in chart XI, the girls begin the period of most rapid growth. Chart XII, showing the mean variation for weight, indicates also a sudden rise in the mean variation at that time. In weight the mean variation increases with advance in years. The contrary was true in the three preceding curves where mental work was involved. It will be remembered also, that in the preceding curves, wherever there was a sudden decrease between two successive ages in ability to discriminate, there was a sudden decrease in the mean variation for the corresponding period. In these purely physiological data, however, the opposite seems to be true. The mean variation in chart XII rises at the point corresponding to the one in chart XI where the rapid growth of the girls begins. Boys in chart XI begin their rapid growth later than girls and in chart XII the sudden rise in the mean variation for the boys begins a year later. From the comparison for \u201c bright,\u201d \u201c average \u201d and \u201c dull \u201d the same negative conclusion is to be drawn as in the following test.\nTest (7): Height.\nThe height was taken in tenths of a centimeter. Column H of table YII is the record of height, the upper figures of each age being in inches, the lower in centimeters and tenths. The height of boys and girls separately is to be found under B and G respectively.","page":70},{"file":"p0071.txt","language":"en","ocr_en":"Mental and physical development of school-children. 71\nThe average individual mean variations for all combined and for boys and girls separately are expressed in columns MV, M V and MV\" respectively. The figures on the left of chart XIII indicate the height in centimeters. Those at the left of chart XIV indicate the variations in centimeters. The ages are marked below in both charts. Almost precisely the same laws appear here in regard to rapidity of growth for the different sexes as appeared in the figures for weight. At 6 the hoys are 114.5om high, the girls 114.0cm. Both boys and girls grow with about the same rapidity, the boys being the taller, until between 11 and 12; here the girls grow much more rapidly and are the taller until between 14 and 16, where the boys are taller. The girls become more nearly stationary in height after 15, while boys make exceedingly rapid progress from 14 on. At 17 the height of boys was 170.50m, of girls 168.6cm. Just before puberty is the period of most rapid growth for girls while the period of most rapid growth falls later for boys, beginning at 14.\nThe statement has been made by Porter that the brighter the child the taller he is.1 Brightness and dullness, however, in his tests were decided by examination-grades, which, it is needless to say, are often very poor mental tests. In my results no such relation could be traced. JMy data are based upon the judgment of the teacher as to what she considered to be the general mental ability or \u201c stand \u201d of the child as it is sometimes called. This is really more accurate than a system of set examinations. The results as tabulated in columns A, B and G of table VII, represent the heights of the children graded according to the judgment of the teacher under whom they fell, A being bright, B those of average ability, and G those who were dull mentally. In the same results, when put in graphic form, the lines cross and re-cross too frequently to be of any value on such a point except to give the negative result as disproof of the statement referred to above.\nThe mean variations in chart XIV furnish one marked exception in the curve for boys to the rule applying so well to weight and even still more forcibly corroborated by the next curve of variation for lung capacity, chart XVI. Chart XIV for variations in height is not without points verifying the rule, however. Variations increase in size with advance in age. Following the curve for girls, at 10 and 11, where the period of very rapid growth begins to show\n1 Porter, The growth of St. Louis children, Transactions of the Academy of Science\nof St. Louis, 1894 VI 335.\n*","page":71},{"file":"p0072.txt","language":"en","ocr_en":"12\nJ. A. Gilbert,\nTable YII. Height.\nAge.\tH\tMV\tB\tMV\tG\n\t45.4\t1.6\t45.0\t1.6\t44.9\n6\t115.4\t3.9\t114.5\t3.9\t114.0\n\t47.3\t1.6\t47.1\t1.6\t46.9\n7\t120.2\t4.0\t119.8\t4.0\t119.1\n\t49.3\t2.0\t48.9\t1.8\t48.4\n8\t125.2\t4.9\t124.2\t4.4\t123.0\n\t61.2\t2.1\t51.2\t2.0\t50.8\n9\t130.2\t5.3\t130.2\t5.1\t129.0\n\t53.0\t2.0\t53.0\t1.7\t52.8\n10\t134.6\t4.9\t134.6\t4.3\t134.0\n\t55.9\t2.4\t55.9\t2.0\t54.6\n11\t142.0\t6.0\t142.0\t5 0\t138.6\n\t57 3\t2.4\t57.0\t2.2\t57.9\n12\t145.5\t6.1\t144.8\t5.6\t147.1\n' 59.9\t\t2.6\t58.8\t2.2\t60.4\n13\t161.0\t6.4\t149.4\t5.6\t153.4\n\t60.9\t3.2\t59.3\t3.4\t61.4\n14\t154.7\t8.1\t150.5\t8.7\t155.9\n\t62.7\t2.9\t62.8\t3.2\t62.5\n15\t159.2\t7.4\t159.5\t8.0\t158.8\n\t64.9\t2.4\t65.7\t2.2\t62.5\n16\t164.8\t6.0\t167.0\t5.4\t168.8\n\t65.6\t2.3\t67.1\t1.3\t63.6\n17\t166.6\t5.9\t170.5\t3.2\t161.6\nUpper figures are inches ; lower figures are centimeters.\nH] height.\nMV, statistical mean variation for total result.\nB, height of boys.\nMV', statistical mean variation for boys.\nG, height of girls.\nitself, the variation rises rapidly.\nMV\"\tA\tB\ta\tN\tNB NG\t\n1.4\t44.2\t46.2\t45.6\t\t\t\n3.6\t112.3\t114.8\t115.8\t98\t50\t48\n1.5\t47.4\t46.8\t47.6\t\t\t\n3.5\t120.6\t119.0\t121.0\t98\t50\t48\n1.8\t48.5\t48.4\t48.2\t\t\t\n4.4'\t123.3\t122.8\t122.3\t96\t49\t47\n1.8\t61.0\t50.9\t50.9\t\t\t\n4.5\t129.4\t129.2\t129.3\t97\t49\t48\n2.1\t52.9\t53.0\t63.0\t\t\t\n5.2\t134.4\t134.6\t134.5\t96\t50\t46\n2.2\t65.1\t54.9\t55.9\t\t\t\n5.6\t140.0\t139.4\t142.7\t101\t51\t50\n2.5\t57.6\t57.3\t69.0\t\t\t\n6.3\t146.2\t145.5\t150.0\t106\t56\t50\n2.3\t5S.0\t60.5\t58.8\t\t\t\n5.8\t147.2\t153.8\t149.3\t110\t51\t69\n2.8\t61.1\t60.7\t60.4\t\u25a0\t\t\n7.1\t155.2\t154.2\t153.3\t104\t50\t54\n2.1\t64.5\t62.6\t62.2\t\t\t\n5.3\t163.8\t159.0\t158.0\t102\t51\t51\n2.1\t65 0\t65.5\t65.0\t\t\t\n5.2\t165.1\t166.3\t165.2\t87\t48\t39\n1.9\t66.5\t65.6\t65.2\t\t\t\n4.7\t169.0\t166.6\t165.6\t91\t47\t44\nMV\", statistical mean variation for girls.\nA,\theight of bright children.\nB,\theight of average children.\nG, height of dull children.\nN, number of children.\nNB, number of boys.\nNG, number of girls.\nAt 12, after the most rapid sec-\ntion of increased rate of growth is completed, the variation falls. With the exception of the one point at 14, chart XIY, which is probably due to puberty, the curve of variations gradually decreases with the corresponding decrease in rapidity of growth, shown in chart XIII. The curve for boys contradicts the rule. There is no evident","page":72},{"file":"p0073.txt","language":"en","ocr_en":"Mental and physical development of school-children. 19,\ncause for the sudden fall in variation from 9 to 10 and again at 14. The curve, instead of rising with the rapid growth shown in chart XIII, falls rapidly till the age 17.\nFig. 18. Chart XIII.\n\u2014 Boys and girls.\n......... Boys.\n----------Girls.\nFig. 19. Chart XIV.\nStatistical mean variation. Statistical mean variations for boys. Statistical mean variations for girls.","page":73},{"file":"p0074.txt","language":"en","ocr_en":"74\nJ. A. Gilbert,\nTbst (8): Lung-capacity.\nThe figures in column IG of table VIII indicate the lung-capacity for the corresponding ages given in the first column. The upper figures of each age represent the number of cubic inches ; the lower figures represent the number of cubic centimeters. These results are also placed in graphic form in chart XV, the figures at the left indicating the number of cubic centimeters, those at the bottom indicating the ages.\nTable Till.\nLung-capacity.\nAge. LG\t\tMV\tB\tMV'\tG\tMV\"\tA\tB\tG\tN\tMB MG\t\n\t62.0\t9.7\t66.0\t9.5\t50.0\t9.5\t52.3\t51.3\t49.0\t\t\t\n6\t832\t155\t896\t152\t800\t152\t\u25a0 837\t821\t784\t94\t49\t45\n\t63.0\t11.8\t66.0\t11.2\t54.0\t11.1\t67.0\t60.0\t67.0\t\t\t\n7\t1008\t189\t1056\t179\t864\t^ 178\t1072\t960\t1072\t96\t48\t48\n\t72.0\t12.3\t73.0\t11.3\t66.0\t10.5\t72.5\t68.5\t67.0\t\t\t\n8\t1152\t197\t1168\t181\t1056\t168\t1160\t1096\t1072\t96\t49\t47\n\t78.0\t13.8\t83.0\t16.3\t72.5\t9.8\t78.0\t72.0\t81.0\t\t\t\n9\t1248\t221\t1328\t261\t1160\t157\t1248\t1152\t1296\t94\t48\t46\n\t87.5\t14.3\t91.5\t15.4\t82.0\t14.3\t90.0\t84.0\t80.5\t\t\t\n10\t1400\t229\t1464\t246\t1312\t229\t1440\t1344\t1288\t96\t50\t46\n\t91.0\t15.9\t104.0\t15.1\t83.0\t10.4\t95.0\t90.0\t91.0\t\t\t\n11\t1456\t254\t1664\t242\t1328\t166\t1520\t1440\t1456\t100\t49\t51\n\t109.0\t16.6\t113.5\t14.1\t104.0\t14.8\t108.0\t110.0\t113.0\t\t\t\n12\t1744\t266\t1816\t226\t1664\t237\t1728\t1760\t1808\t103\t56\t47\n\t116.0\t19.4\t120.0\t17.5\t105.0\t18.8\t116.0\t116.0\t102.0\t\t\t\n13\t1840\t292\t1920\t280\t1680\t301\t1856\t1856\t1632\t107\t60\t57\n\t117.5\t22.7\t125.0\t23.9\t105.0\t17.4\t119.5\t118.5\t97.5\t\t\t\n14\t1880\t363\t2000\t382\t1680\t278\t1912\t1896\t1560\t101\t49\t52\n\t131.3\t22.3\t161.0\t29.8\t116.0\t15.5\t143.5\t123.0\t131.0\t\t\t\n15\t2101\t356\t2576\t477\t1856\t248\t2296\t1968\t2096\t102\t51\t51\n\t149.0\t39.0\t187.0\t30.8\t115.0\t16.1\t137.0\t166.3\t128.5\t\t\t\n16\t2384\t624\t2992\t493\t1840\t258\t2192\t2660\t2056\t87\t48\t39\n\t156.0\t42.0\t204.0\t33.4\t118.5\t18.5\t180.0\t129.5\t169.0\t\t\t\n17\t2496\t672\t3264\t534\t1896\t296\t2880\t2072\t2704\t91\t47\t44\nUpper figures are cubic inches; lower figures are cubic centimeters.\nLG, lung-capacity.\nMV, statistical mean variation for total result. '\nB, lung-capacity for boys.\nMV, statistical mean variation for boys. G, lung-capacity fdr girls.\nMV\", statistical mean variation for girls.\nA,\tlung-capacity of bright children.\nB,\tlung-capacity of average children.\nG, lung-capacity of dull children.\nM, number of children.\nMB, number of boys.\nMG, number of girls.","page":74},{"file":"p0075.txt","language":"en","ocr_en":"Mental and physical development of school-children.\n75\nFig. 20. Chart XV.\n------\u2014 Boys and girls.\n....... Boys.\n-------Girls.\nBoys have a larger lung-capacity than girls throughout. At 6 boys have a capacity of 896ccm while the girls have only 800Gcm. This difference between boys and girls increases but very slightly, in favor of boys, till the age of 12 where boys have a capacity of 1816ccm and girls 1664ccm. From this age on the development of girls is much slower. Almost no growth occurs between 12 and 14. From 14, at which age their lung-capacity is 1080com, a gain is made to 1856oom at 15. From 15 to 17 almost no development of the lungs is noticeable, for at 17 they have attained only 189600m. The curve for boys shows a marked difference from that of girls. About the same rate of growth as that from 6 to 7 was maintained till the age of 14, at","page":75},{"file":"p0076.txt","language":"en","ocr_en":"16\nJ. A. Gilbert,\nwhich age their lung-capacity was 2000com. While the girls become nearly stationary at 12, the hoys do .not begin their most rapid growth until 14. Between 14 and 15 they make a gain of 576ccm, and they keep up this rapid growth until 17, which is as far as my experiments extended. At 17 the lungs of the average boy contained 3264ocm ; those of the average girl 1896com.\nThe mean variations are put in graphic form in chart XVI. The numbers to the left indicate the average mean variation in cubic centimeters.\nFig. 21. Chart XVI.\n------\u2014\u2014 Statistical mean variation.\n........ Statistical mean variation for boys.\n---------Statistical mean variation for girls.\nThe mean variation increases with advance in years. From 6 to 13 there is a gradual rise in the variation. At this age the increase in lung-capacity almost ceases for girls and so also does the variation. Chart XV shows almost no increase in lung-capacity between the years 12 and 14. The variation for the corresponding years in chart XVI shows a fall but with a rise again at 14 where the lung-capacity begins to increase as shown by chart XV.\nAt 13 for boys it is just the opposite. Variations rise very rapidly as does the growth in lung-capacity, the latter appearing one year later. The coincidence between changes in growth and changes in variation are very noticeable in all the physiological curves.\nThe mean variation, for both boys and girls combined, as is shown in the solid line of chart XVI, increases very rapidly from 13 to 17 owing to the fact that girls after 13 grow but little more while boys undergo most rapid growth thereafter, thus of course throwing the mean variation for the total result much higher.","page":76},{"file":"p0077.txt","language":"en","ocr_en":"Mental and physical development of school-children.\n77\n'\tTest (I\u00d4) : Reaction-time.\nIn taking up this section of the results we return to the mental processes in contra-distinction to the three preceding tests, which were purely physiological. In explaining apparatus and methods, tests (9) and (10) were treated in a different order from that in which they were taken, here it seems convenient and proper also to reverse the order on account of the relative complexity of the two. The simple reaction time alone will he considered first. In the following three tests the arithmetical averages were calculated as well as the median values. In order to show the difference between the results, as calculated by the two different methods I have tabulated the arithmetical averages under Ta, and the median values under Tp. The same comparison is drawn by the graphic method in the chart, the dotted line being the arithmetical averages and the solid lines the median values. In order to illustrate the method of median values I have selected from my results a card of a boy 8 years old. The point of objection to the arithmetical average is brought out somewhat more plainly in the following figures than would be the case with the average card but by choosing a somewhat extreme case, the underlying principle can be most easily seen and the difference made all the more forcible for illustration. As was explained under methods, each child was given ten trials. The results for the ten reactions of this 8-year-old boy were as follows : 24, 23, 48, 22, 21, 24, 43, 21, 22, 19. The arithmetical average of these ten is 26.7, whereas the median value, or the value half way between the fifth and sixth counting either from the largest or from the smallest as 1, is 22.5. The variations of each result from the mean value are 1.5, 0.5, 25.5, 0.5, 1.5, 1.5, 20.5, 1.5, 0.5, and 3.5 respectively, making a mean variation of 5.7. A glance at the original data will show that in order to get what we would consider the representative reactiontime of that boy, 48 and 43 ought not have as much influence given them as 21, 22 and 23 which fall nearer the average. By the median value, instead of allowing them to count in direct proportion to their size, they are rather allowed to count as one in a series of ten. However, these extreme data such as 48 and 43, are not allowed to pass unnoticed by the method of median values without exciting any influence whatever. On the contrary their influence is felt in the mean variation for the child where their effect properly belongs. In this the average of mean variations for the child is 5.7. Had it not been for the two figures 48 and 43 his mean variation would have been only 1.4 instead of the 5.7. They increase this average and","page":77},{"file":"p0078.txt","language":"en","ocr_en":"78\nJ. A. Gilbert,\nTable IX.\nReaction-time.\nAge.\tTa\tTp\tmv\tMV\tB\tMV\tG\tMV\"\tA\tB\tG\tN\tNB\tNG\n6\t31.7\t29.5\t5.6\t5.0\t28.2\t4.6\t29.5\t5.4\t28.5\t29.6\t28.3\t99\t50\t49\n7\t30.9\t29.2\t5.4\t5.5\t26.7\t4.6\t31.5\t5.2\t29.2\t29.5\t28.2\t98\t50\t48\n8\t28.7\t26.2\t4.9\t3.9\t24.5\t3.9\t26.0\t3.1\t26.6\t25.8\t28.6\t96\t49\t47\n9\t26.9\t25.0\t4.1\t4.1\t24.3\t5.4\t25.5\t4.9\t23.2\t25.3\t26.8\t99\t50\t4\u00bb\n10\t23.3\t21.5\t4.2\t3.6\t21.0\t2.6\t22.5\t4.3\t21.0\t20.5\t26.0\t97\t50\t47\n11\t21.0\t19.5\t3.7\t3.4\t18.5\t3.1\t20.6\t3.4\t19.8\t19.8\t19.2\t101\t50\t51\n12\t20.7\t18.7\t3.6\t3.1\t17.8\t2.7\t19.8\t3.5\t18.3\t19.5\t19.5\t106\t56\t50\n13\t20.5\t18.7\t3.3\t3.0\t17.8\t2.9\t20.5\t3.5\t18.5\t18.5\t22.5\tno\t51\t59\n14\t19.1\t18.0\t3.0\t2.9\t18.0\t3.0\t18.7\t3.0\t16.8\t17.6\t19.3\t104\t50\t54\n15\t18.4\t17.2\t3.0\t2.7\t16.7\t2.3\t18.9\t2.7\t16.0\t17.0\t19.0\t102\t51\t51\n16\t17.0\t16.5\t2.8\t2.3\t14.7\t1.6\t17.2\t2.6\t15.5\t16.0\t15.0\t87\t48\t39\n17\t17.0\t15.5\t3.0\t3.3\t14.7\t1.9\t16.3\t2.6\t14.8\t15.5\t16.2\t91\t47\t44\nTa, reaction-time in hundredths of a\t\t\t\t\t\tsecond\tG,\treaction-time for girls in hundredths of\t\t\t\t\t\ta\n\u2014arithmetical averages.\nIp, reaction-time in hundredths of a second\u2014 median values.\nmv, average individual mean variation.\nMV, Statistical mean variation.\nB, reaction-time for boys in hundredths of a second.\nMV, statistical mean variation for boys.\nsecond.\t-\nMV\", statistical mean variation for girls.\nA,\treaction-time of bright children.\nB,\treaction-time of.average children.\n0, reaction-time of dull children.\nN, number of children.\nNB, number of boys.\nNG, number of girls.\nFig 22. Chart XVII.\nBoys and girls.\nBoys:\nGirls.\nBoys and girls, arithmetical average.","page":78},{"file":"p0079.txt","language":"en","ocr_en":"Mental and physical development of school-children.\n79\nFig. 23. Chart XVIII.\n------------Statistical\tmean\tvariation.\n...........Statistical\tmean\tvariation for boys.\n------------Statistical\tmean\tvariation.\n---------\u2014 Average individual mean variation.\nFig. 24. Chart XIX.\n--------Bright.\n........Average.\n--------Dull.\njustly so, for, by the mean variation we wish to indicate the irregularity of his separate results from the general average. The median was Calculated for both boys and girls combined, and also for each separately. The mean for boys and girls combined according to arithmetical averages always falls half way between those for boys","page":79},{"file":"p0080.txt","language":"en","ocr_en":"80\nJ. A. Gilbert,\nand girls separately ; not so with the median. The median for boys and girls combined frequently falls below or above both that of the girls and that of boys when taken separately. Illustrations of this can be seen in charts IX, age 13 ; XII, age 7 ; XVII, age 8; XXII, age 14; XIII ages 6, 7, 8 and 11. This difference of the median from the average clearly shows the heterogeneity of the two classes.\nIt must also be noted that mean variations for boys and girls combined are much larger than for each separately, which also shows the heterogeneity of the data.\nThe time of simple reaction decreases with age. Boys and girls at 6, when averaged together, react in 29.5 hundredths of a second. This decreases to the age 12 where the time is 18.7 hundredths of a second. From 12 to 13 no increase is made, remaining at 18.7 for 13 also. From 13 on, there is gradual increase until 16 when the time is 15.5 hundredths of a second. At 17 no gain is made.\nThe results, when considered for girls and boys separately, show marked difference in sex. Girls are slower at 7 than at 6. At 6 the time required was 29.5 while at 7 they required 31.5. At 8 there was a gain to 26.0. From this on there was a gradual gain in ability and a decrease in time till 12, where the time was 19.8. At 13, however, 20.5 hundredths of a second were again required leaving the girls only one thousandth of a second better at 13 than they were at 11. After this there was an increase again till 17 where the reactiontime for girls was 16.3.\nThe curve for boys shows no change from the general law of increase from 6 to 7. From 12 to 14 there is a marked difference in the rapidity of increase. At 12 the time required was 17.8 ; at 13 it was the same ; at 14 there is a loss in ability, the time being 18.0. Thus the boys were worse at 14 than at 12 and but very little better than they were at 11. After 14 they again increased with almost the same rapidity as they did before 11 until 16 and 17 where 14.7 hundredths of a second were required. Both boys and girls seemed to increase less rapidly from eight to nine than at the other ages. Boys were quicker than girls throughout.\nThe mean variations, represented in chart XVIII, decrease with advance in years. For boys, during the period from 11 to 14 when the actual time of reaction remained almost stationary, the mean variation did the same, showing a slight difference at 12 in the same way as the curve for boys in chart XVII. There is also a marked break in the curve of variation from 8 to 9 corresponding to the slight decrease in the rate of ability at the same ages in chart XVII.","page":80},{"file":"p0081.txt","language":"en","ocr_en":"Mental and 'physical development of school-children. 81\nThe relation between mean variation and mean reaction-time is rendered most marked by comparing the curves in charts XVII and XVIII for both boys and girls combined. At most points where there is a marked change in rate of increase in chart XVII there is also a corresponding change in the variation at that age. In this, age 13 offers the only exception. Wherever the rate of increase in ability from one age to another is less than the average rate of increase, the variation for that period becomes higher and therefore worse.\nIn this test also the data were separated and recalculated to find the reaction-time of those who were bright, of average mental ability and dull respectively. The results are recorded in columns A, B and G respectively, table IX. The difference here becomes very'noticeable as can be seen by referring to the graphic representation, chart XIX. The bright children react much more quickly than the dull. Not so much difference is noticeable between those who were considered bright by the teacher and those who were judged of average ability. It is shown here that we judge of a child\u2019s mental ability by the quickness or rapidity with which they were able to act. Another fact is that all children are considered of about equal mental ability, or in other words, all grades of children react in about the same length of time just before those ages in which changes of growth manifested themselves, viz : 11 and 16. The average reaction-time of all ages for bright children was 20.7 hundredths of a second; for those of average ability it was 21.3 ; for dull children 22.4.\nTest (9): Reaction with discrimination and choice.\nHere, as in the other mental tests, ability increased and the length of time required decreased with advance in age. This test implies more complicated mental activity and, as would be expected, the influences which affect mental life show themselves more plainly in the curve representing such development. For some cause or other development between 6 and 7 is arrested for girls here, as well as in the test on reaction-time. Boys seem to suffer no such back-set but, starting at 53.5 hundredths of a second, continually increase from 6 till 13. From 13 to 14 they suffer a slight loss after which they gain till 17, losing slightly, however, from 15 to 16. At 17 the time required for boys was 30.5 hundredths of a second. Boys may be said to undergo only one loss, that being also of small moment. Girls suffer two marked losses, the first from 6 to 7, increasing the time required from 51 hundredths to 52.8 hundredths of a second. After 7 6","page":81},{"file":"p0082.txt","language":"en","ocr_en":"82\nJ. A. Gilbert,\nTable X.\nReaction with discrimination and choice.\nAge.\tTa\tTp\tmv\tMV\tE\tB\tMV\tG\tMV\"\tA\tB\tG\tN\tNB\tNG\n6\t55.8\t52.5\t10.2\t6.0\t1.1\t53.5\t6.3\t51.0\t6.5\t62.3\t51.0\t54.5\t99\t50\t49\n7\t54.1\t53.0\t9.4\t8.1\t1.1\t49.0\t8.8\t52.8\t9.4\t52.0\t52.7\t55.5\t97\t49\t48\n8\t48.8\t47.8\t8.5\t6.5\t.9\t48.0\t5.7\t47.5\t5.5\t47.5\t47.5\t50.0\t96\t49\t47\n9\t47.5\t45.0\t8.1\t6.8\t1.2\t44.5\t6.3\t46.0\t7.2\t45.8\t45.0\t42.3\t98\t49\t49\n10\t42.2\t41.0\t7.3\t4.9\t1.2\t40.0\t4.9\t41.5\t4.5\t39.7\t41.0\t45.5\t97\t50\t47\n11\t40.5\t38 5\t7.0\t5.8\t1.2\t38.7\t5.8\t38.8\t5.7\t39.0\t38.0\t38.0\t101\t50\t51\n12\t38.9\t37.0\t6.1\t5.5\t1.1\t38.5\t6.0\t37.0\t4.9\t37.0\t36.5\t37.0\t106\t56\t50\n13\t39.9\t39.5\t6.2\t5.8\t1.2\t36.0\t5.1\t41.5\t5.5\t39.0\t38.1\t42.8\t110\t51\t59\n14\t36.3\t36.5\t6.5\t4.9\t.9\t36.7\t4.5\t35.5\t5.4\t33.5\t36.3\t36.8\t104\t50\t54\n15\t34.8\t33.5\t5.9\t4.9\t.8\t31.1\t5.5\t34.5\t3.8\t30.5\t34.0\t36.5\t102\t51\t51\n16\t34.0\t32.5\t5.4\t4.3\t1.0\t31.5\t3.9\t35.0\t3.9\t32.7\t32.7\t34.3\t87\t48\t39\n17\t32.1\t31.2\t5.4\t4.0\t.7\t30.5\t3.5\t31.5\t4.4\t32.5\t30,0\t31.2\t91\t47\t44\nT a, discrimination-time in hundredths of a second\u2014arithmetical averages.\nTp, discrimination-time in hundredths of a second.\nmv, average individual mean variation.\nMV, Statistical mean variation.\nE, average number of errors made by reacting to red.\nB, discrimination-time for boys in hundredths of a second.\nMY. statistical mean variation for boys.\nG, discrimination-time for girls in hundredths of a second.\nMV\", statistical mean variation for girls.\nA,\tdiscrimination-time for bright children.\nB,\tdiscrimin\u00e2t!on-time for average children.\n0, discrimination-time for dull children.\nN, number of children.\nNB, number of boys.\nNG, number of girls.\nthey increase in ability very rapidly till the age 12, where the length of time was 37 hundredths. From 12 to 13, however, they lose just as much as they had gained during the two years preceding 12, thus requiring 41.5 hundredths of a second at 13 which is the same length of time required as at age 10. After 13 comes another very rapid gain till 17, with the exception of a small loss from 15 to 16 similar to the loss experienced by the hoys at that age. At 17 the time required for girls was 31.5 hundredths of a second. Boys are better in this test than girls. The average of all the boys of all ages is 39.8 while that of the girls is 41. Not quite so much difference is seen here, however, as in the simple reaction-time where the average for boys was 20.2 while that of the girls was 22.3.\nColumns A, B and C of table X show the length of time for bright, average and dull children respectively. In these results not quite so much difference is noticeable, which is perhaps due to the fact that they contain a somewhat smaller element of reaction-time, to which brightness and quickness are such close correlates. In this test, when all ages are considered, 40.1 is obtained as a result for bright","page":82},{"file":"p0083.txt","language":"en","ocr_en":"Mental and physical development of school-children.\n83\nFig. 25. Chart XX. Boya and girls.\nBoys.\nGirls.\n-----Arithmetical averages\u2014hoys and girls.\nchildren ; for average children, 40.2, and for the dull ones an average of 42.0 hundredths of a second. It is very evident from these'figures that in this test the rule also applies that the brighter the child the more quickly he is able to react with discrimination and choice.\nThe average of the mean variations for separate children, shown by the dotted line, chart XXI, decreases gradually with age except from 12 to 14 where there is a marked increase, showing undoubtedly the effects of puberty during that period.\nSo far as the comparative mean variations for boys and girls are concerned, but little can be said, since the curves cross and re-cross","page":83},{"file":"p0084.txt","language":"en","ocr_en":"84\nJ. A. Gilbert,\nso frequently as to be of little value for comparisons between them and those in the main curve for development. The same general agreement exists between the main curve and the curves for variation in that there is increase in both with advance in years.\nAs explained under apparatus and methods the child was asked to react when blue appeared in the stimulating apparatus and not to react when red appeared. It is difficult for anybody to keep from reacting to the red, for the reaction becomes somewhat automatic and, if the attention flags, not infrequently reaction to red follows.\nFig. 26. Chart XXI.\nStatistical mean variation. Statistical mean variation for boys. Statistical mean variation for girls. Av\u00e9rage individual mean variation.\nColumn E of table XI records the average number of reactions each child made to red out of the twenty trials given him. In order to be sure that the child discriminated between blue and red, as many reds had to be disclosed as blues, being irregularly mixed so that the numbers in column E would represent the number of mistakes made in 20 instead of 10, the latter of which would only represent the reactions to blue. Twenty of the 1192 children tested made the error of reacting to the red four times during the series of trials. Out of 1192 tested 420 made no errors at all by reacting to the red.","page":84},{"file":"p0085.txt","language":"en","ocr_en":"Mental and physical development of school-children.\n85\nTest (11): Time-memory.\nAs in the preceding tests, also in this one, ten trials were given each child and after taking the median value of these, the average of the mean variations for the separate results or data was calculated. Besides taking the median, the arithmetical average was taken for the sake of comparison. The arithmetical averages are to he found recorded in column JSa and the median values in column Ep of table XI. The median values for boys and girls are placed in columns B and G respectively. The averages of the mean variations for separate children are in the column headed mv; M Vrepresents the mean variation for the total result, while MV and MV\" give the same for boys and girls respectively.\nColumns Ea and Ep are used in constructing the two curves of chart XXY for the sake of comparing the results according to the two methods. Ages are at the bottom on the line of abscissas. The figures to the left indicate in hundredths of a second the amount of-error made in making the second sound the same length as the first, which was two seconds long. The second sound was always made too short and the numbers thus indicate the amount of shortage in hundredths of a second.\nThe length of time, by using the arithmetical averages, is less than the median values from 6 to 10 years of age. Here, the curves, representing the result in graphic form, cross. From 10 to 15 the error is greater by arithmetical averages than by median values ; from 15 to 16 the error is less ; at 17 it is worse again. In calculating the results of this test the use of the method of median values is of still more importance than in the preceding tests, owing to the fact that the variations are sometimes extremely large. Frequently results were obtained in which all but one or two fell short of the correct time by 40 hundredths of a second or more while these two exceptions, owing to some disturbance or distraction either external or internal, were 20 or 25 hundredths too long. Accuracy with small mean variation demands a perfectly even flow of consciousness. During the first sound of two seconds the child simply sits and listens with no responsibility as to how long the sound shall go ; all he has to do is to judge its length. When it becomes his turn to make the sound his responsibility and continuous wondering whether the sound is yet long enough make the time seem longer than it really is and consequently he stops it too soon.\nThe effect of suggestion in such a test is peculiar. For my tests the separate records of the child were, of course, kept secret until all","page":85},{"file":"p0086.txt","language":"en","ocr_en":"86\tJ. A. Gilbert,\nTable XI.\nTime-memory.\nAge\t!. Ea\tEp\tmv\tMV\tB\tMV\tG\tMV\"\tA\tB\tG\tN\tNB NG\t\n6\t56.7\t62.0\t24.6\t23.4\t56.5\t25.1\t67.0\t23.2\t55.5\t68.5\t69.5\t94\t52\t42\n7\t59.6\t66.5\t27.9\t20.2\t63.5\t20.6\t68.5\t20.4\t66.8\t66.5\t67.3\t96\t49\t47\n8\t52.7\t54.3\t23.6\t22.8\t48.5\t22.3\t57.0\t22.3\t48.|>\t59.3\t69.0\t96\t49\t47\n9\t56.2\t60.0\t23.0\t23.5\t47.5\t22.4\t73.5\t19.3\t50.0\t65.0\t46.5\t97\t49\t48\n10\t48.9\t48.5\t20.2\t18.1\t48.5\t21.8\t46 5\t15.8\t40.3\t49.5\t69.5\t95\t49\t46\n11\t44.2\t41.0\t20.8\t18.2\t40.5\t16.6\t41.0\t20.2\t45.0\t42.0\t48.0\t101\t50\t51\n12\t41.6\t36.8\t17.6\t21.3\t35.8\t21.8\t37.5\t18.7\t28.5\t49.3\t44.5\t106\t56\t60\n13\t36.3\t33.0\t17.9\t21.4\t24.5\t22.0\t36.0\t19.5\t36.0\t25.8\t33.5\t110\t51\t59\n14\t35.9\t30.0\t18.7\t16.1\t31.5\t14.2\t31.0\t17.8\t28.3\t28.8\t42.5\t103\t49\t54\n15\t37.6\t38.0\t18.0\t19.4\t34.5\t15.3\t39.0\t21.9\t22.5\t36.0\t45.0\t102\t51\t51\n16\t41.6\t44.0\t16 6\t16.7\t38.0\t16.5\t49.0\t14.0\t43.3\t39.3\t47.0\t87\t48\t39\n17\t39.9\t35.5\t13.8\t15.8\t34.0\t13.8\t40.0\t17.8\t33.5\t38.8\t31.3\t91\t47\t44\nEa, hundredths of a second short in memory of two seconds\u2014arithmetical averages.\nEp, hundredths of a second short in memory of two seconds\u2014median values.\nmv, average individual mean variation.\nMV, statistical mean variation.\nB, hundredths of a second short for boys.\nMV, statistical mean variation for boys.\nG, hundredths of a second short for girls.\nMV, statistical mean variation for girls.\nA,\thundredths of a second short for bright children.\nB,\thundredths of a second short for average children.\nC,\thundredths of a second short for dull children.\nN, number of children.\nNB, number of boys.\nNG, number of girls.\nhad been taken. After taking the series of ten trials I again tried a number of individuals telling them each time the amount of error made. They soon learned to correct their error somewhat and not infrequently made the sound too long instead of too short.\nA few of the younger children made the second sound not quite half as long as it should have been, making an error of more than 100 hundredths of a second. Only 38 out of the 1192 tested in all, judged the sound longer than it really was. It is interesting to note also that 19 out of these fell in the two ages 12 and 13, the former having 9 and the latter 10, none of the other ages having more than three each.'\nIn time-memory the average child is worse at 7 than at 6, worse at 9 than at 8 and worse at 16 than at 14. The irregularity at the period of. puberty falls later in the curves of this test than in the others. After the second decrease in ability from 8 to 9 there is a rapid increase in ability till 14. Thereafter it is reversed and there is more rapid loss than there was previous gain, leaving the child con-","page":86},{"file":"p0087.txt","language":"en","ocr_en":"Mental and physical development of school-children.\n87\n\\\nFig. 27. Chart XXII.\n----Boys and girls.\n.... Boys.\n----Girls.\n----Arithmetical averages.\nsiderably worse at 16 than he was at 12. From 16 to 17 there is another rapid increase in accuracy. At 6 the child is 62 hundredths in error ; at 7 the error is 66.5 ; at 8 it is 54.3. After rising again at 9 to 60 there comes the rapid increase in accuracy till the best point is reached at 14 where there is only an error of 30 hundredths of a second.\nThe results, when divided into boys and girls, show two very distinct differences. Both boys and girls lose from 6 to 7. With the exception of a very slight change in the average increase from 8 to","page":87},{"file":"p0088.txt","language":"en","ocr_en":"88\nJ. A. Gilbert,\n10, boys grow better till the age 13. Girls from 8 to 9 undergo an enormous loss, making the sound at the latter age 73.5 hundredths of a second too short. Thus, at this age they are far worse than at any other period between 6 and 17. From 9 to 10 an exceedingly rapid gain is made^and thereafter there is a continuous gain till 14, instead of stopping at 13 as the boys did. Boys and girls both lose from this point till 16 where they again begin gaining. At 13 is the best time for boys, their error being only 24.5 hundredths too short ; girls reach their best point at 14 with an error of 31 hundredths of a\nFig. 28. Chaht XXIII.\n----------Statistical mean variation.\n.......... Statistical mean variation for boys.\n----------Statistical mean variation for girls.\n----------Average individual mean variation.\nsecond. In this test also, boys greatly excel the girls, as can be seen by comparing columns B and G of table XI and also the curves of chart XXII.\nIn recalculating the results for comparison between bright, average and dull children the amounts of error made by them are 41.5, 47.4 and 51.1 respectively. The separate averages for each age and grade of children are recorded in columns A, B and U of table XI.\nIn general, ability increases with advance in years. This same is true of the curves of chart XXIII, representing the mean variations for time-memory. There is one thing here which is important as","page":88},{"file":"p0089.txt","language":"en","ocr_en":"I\nI\nMental and physical development of school-children. 89\ncorroborating the conclusion referred to under reaction-time, viz: that where a special change in relative growth between two ages occurs for the better, the mean variation changes for the worse. In chart XXIV the mean variation for both boys and girls decreases from 6 to 7, whereas the general ability for time-memory, chart XXII, increases for the corresponding period. The same can be noticed also in ages 8 to 10 and 14 to 16 where the most marked changes occurred.\nGeneral comparison oe sex.\nIn order to get a general estimate of the mental differences of sex from the results obtained, the final averages of each age in muscle-sense, sensitiveness to color-differences, force of suggestion, reactiontime, reaction with discrimination and choice, and time-memory were thrown together into a general average for the respective ages. These general averages are recorded in table XII. The same are presented in the curves of chart XXIV. The ages are indicated at the bottom on the line of abscissas. The figures at the left can be given no definite value except to serve as relative points by which to judge the curves. The higher the figure the worse the record, just as was the case in the tests mentioned above. Voluntary motor ability and fatigue were not included in this general average both on accou nt of their having a somewhat different nature from the rest, and, also one was the reverse of the other in that, in fatigue the lower the figure the better the record while the reverse was true for voluntary motor-ability. Could these two have been included, however, the result would have been all the more in favor of boys for it will be remembered that when these two were reduced to per cent, and considered together the balance was greatly in favor of boys. The boys became tired sooner but they also tapped much faster.\nThe only superiority shown for the girls is a small margin of advantage in discrimination for color-differences, referred to on page 48 ; the boys have the advantage very decidedly until between 7 and 8 but thereafter girls are better.\nThe general trend of the curves of chart XXIV is very interesting. Age 11 seems to be a neutral point where boys and girls are of about the same ability. From this age, the curves, on the whole, diverge in opposite directions more and more to the ages 6 and 17.\nThe general law of increase in ability is shown also very plainly by general averages taken in this way and represented in graphic form, as found in chart XXIV.","page":89},{"file":"p0090.txt","language":"en","ocr_en":"90\tJ. A. Gilbert,\nTable XII.\nGeneral comparison of sex.\nAge.\tB + G\tB\tG\n6\t35.1\t34.1\t36.4\n1\t36.4\t34.3\t36.8\n8\t32.9\t31.6\t33.3\n9\t33.0\t30.8\t35.5\n10\t28.4\t21.1\t28.5\n11\t25.8\t25.1\t25.8\n12\t24.5\t24.1\t25.0\n13\t23.5\t21.4\t24.6\nU\t21.9\t21.5\t22.1\n15\t22.8\t21.3\t24.0\n16\t23.2\t21.4\t25.4\n11\t20.1\t19.2\t22.0\nThe figures of the table tiye numbers deduced tests.\tare rela-from the\tB+ G, boys and girls. B, boys. G, girls.\t\n\\\\ / \\\nFig. 29. Chabt XXIV.\n----------Boys .and girls.\n......... Boys.\n----------Girls\u00ab","page":90},{"file":"p0091.txt","language":"en","ocr_en":"Mental and physical development of school-children. 91\nInter-relation of the results of the different tests.\nThe tests described in the preceding pages may be divided into two kinds, mental and physical. The close correlation of mind and body would naturally lead one to expect the closest sympathy between the two.\nFirst, let us give a glance at the relations existing among the three physical curves, viz: weight, height and lung-capacity. Weight and height conform to almost exactly the same rules. In both, very slight differences exist between boys and girls until the period arrives at which boys begin to grow as men and girls as women. Boys are slightly heavier and taller than girls till between 11 and 12. Then the order is reversed. In both height and weight girls excel until between 14 and 15 where boys become heavier and taller and remain so the balance of life. The most rapid growth of girls ceases at 13 while at 14 the rapid growth for boys is just beginning. This difference between the growth of the sexes is all the more forcible when the curves for height and weight, charts XI and XIII, are compared with the one for lung-capacity, chart XY. After 12 the girls gain but very little in lung-capacity while the boys do not begin their real growth until 14. That the turning-point in life comes later for boys than for girls is verified not only by all the so-called physical curves but also by those which make the mental aspects more prominent. In all three physical curves there is the same general correspondence between the main curve for each test and its accompanying curve for mean variations. In all, the variation increases with advance in years and when separate periods of each curve are considered the rate of increase or decrease in mean variations changes wherever there is a marked change in the rate of growth. The mean variations for boys and girls in the physical curves are largest during the years from 12 to 15.\nIn considering the so-called mental curves there is increase in ability with advance in years with the exception of the test on the force of suggestion. In this ability decreases till 9 in the sense that the suggestion is allowed to have more force ; but, thereafter there is a gradual improvement as the suggestion decreases in strength.\nAt first sight the curve for mean variations of sensitiveness to color-differences, chart IY, seems to offer a marked .exception to the general rule, that in all mental tests the mean variations decrease with advance in years. This is not the case. The mean variation rises from 6 to 9 because during those ages a large per cent, of the data were tens, which indicates that all ten colors seemed, exactly","page":91},{"file":"p0092.txt","language":"en","ocr_en":"92\nJ. A. Gilbert,\nalike to those children. Consequently, the larger the per cent, of those picking out all ten as alike, the smaller the mean variation becomes for the data at hand ; but, could the 57 per cent, of nondiscriminations at 6 be turned into the actual data which they could represent, the mean variation would be a great deal larger at 6 than what it is, viz : 1.8. Fifty-seven cases of non-discrimination necessitates 57 out of 100 of my data being the same: 10. This of course throws the mean variation very low.\nIn voluntary motor ability, chart VII, and fatigue, chart IX, more of the physical is involved, so that the relation between them and the two curves for weight and height is very marked. Voluntary motor ability from 12 to 14 is very probably affected by the very rapid growth for the corresponding period shown in charts XI and XIII. Separate relations exist for boys and girls between the curves for voluntary motor ability, fatigue and the three physical curves. The change in rapidity of growth for girls comes between 12 and 13 in weight, height and chest-capacity. The same change occurs at the same period in both voluntary motor ability and fatigue. For boys the marked change in rapidity of growth comes later than for girls, the former always changing radically at 14 as can be seen in charts XI, XIII and XV. In fatigue also the loss at puberty occurs later for boys than for girls, being at 14 instead of at 13 as it was for the girls. In voluntary motor ability the loss commences for both at the same place, viz: 12, but girls suffer loss for two successive years while boys lose only for one.\nIn voluntary motor ability the mean variation changes but slightly for different ages but in fatigue there is a more noticeable decrease in variation with advance in years.\nThe tests which are more strictly mental may be divided into two sections ; the first composed of tests (1), (2) and (3) and the second of tests (9)', (10) and (11).\nIn muscle-sense, test (1), the effect of puberty on the rusults is very marked as is shown by chart I, but in discrimination for color-differences almost no divergences whatever can be noticed at that period. In the curve for force of suggestion, boys and girls alike suffer a loss in ability from 14 to 15. The curves of mean variations in these three tests all show marked divergences from the general trend during the years from 12 to 15. By throwing the muscle-sense and force of suggestion into relation, a purely mental element is brought out in the latter. Had the weight been subjected to the muscle-sense alone the discriminative ability by that sense would","page":92},{"file":"p0093.txt","language":"en","ocr_en":"Mental and physical development bf school-children. 93\nalways have said they were of equal weight, for, by test (1); and chart I, it is shown that discrimination for weight increases gradually with age, but by considering the element of sight we get a measure of our error in judgment in test (3), chart V.\nIn tests (9), (10) and (11), where more quickness and accuracy of action is involved, the effects of puberty show themselves far more plainly than in any of those hitherto considered. Thus, it might be concluded that puberty has a greater effect on the mental than upon the physical aspects of man\u2019s nature. The difference is far more noticeable in girls than in boys as can be readily seen by referring to charts XVJI, XX and XXII. This is specially noticeable in chart .XXIV for the comparison of sex. The development of girls is far more seriously affected by periodic changes than that of boys as can be seen by reference to 7, 9, 14 and 16 of this chart. In discrimination time, chart XX, the loss in ability for girls comes before that of boys, the former beginning at 12 and the latter at 13. This order is reversed in timermemory, chart XXII, and comes later for both, boys beginning to lose in accurrcy at 13 and girls not until 14. This difference between discrimination-time and time-memory is brought out all the more forcibly by.considering the respective .curves for boys and girls combined, charts XX and XXII. In the former the loss is between 12 . and 13; in the latter it occurs between 14 and 16.\nThe mean variation for the separate ages in tests (9), (10) and (11) furnish but little suggestion as to the effect of puberty. The averages of the individual mean variations for separate children show marked changes from 12 to 14 in discrimination and time-memory but nothing in simple reaction-time as is shown by the dash double dot lines of charts XVIII and XXVII. \u25a0\nIn all the curves involving a time-element there is marked loss in ability from 6 to 7 as can be seen in charts XVII, XX, XXII and IX. In reaction-time and reaction with discrimination and choice, charts XVII and XX, the loss is only experienced by girls, but in the other two, time-memory and fatigue both alike suffer some set-back from 6 to 7. The same thing is noticeable to a less degree in muscle-sense and color discrimination, charts I and III, the boys alone suffering loss in color-sensitiveness. The general fact, however, is brought out very forcibly in comparative curves of sex, chart XXIV.\nAn interesting fact is brought out by throwing graded reaction and the same with discrimination and choice into relation with each other.","page":93},{"file":"p0094.txt","language":"en","ocr_en":"94\nJ. A. Gilbert,\nBetween 11 and 12, just before puberty, in both curves the bright and dull children act with about the same rapidity, though both before and after that age the dull ones are much slower than the bright ones. It is evident from a glance at the two charts XIX and XXII that the child is judged dull at 13 because he is unable to act as quickly. Considering these charts in conjunction with the comparative curves of sex, chart XXIV, the conclusion is suggested that all children on an average are of about equal ability at age 11.\nRelation or individual tests to general mental ability.\nThe data for the tests on weight, height, lung-capacity, discrimination-time, reaction-time and time-memory were recalculated to get the relation between the Separate tests and general mental ability as estimated by the teacher. The curves for height and reaction time were inserted in part II under tests (7) and (10) respectively. The curves for height, worked out in relation to \u201c stand \u201d are found in chart XV and those for reaction time in chart XIX. The remainder of the curves belonging to this class have been given a separate section on account of their largely negative value. It will be remembered that the curves for height were of negative value in that no marked relation could be traced between them and the mental ability of the pupils upon whose measurement they were plotted. The same is true of weight ; also of chest capacity with the exception of the years 13 and 14 where the dull pupils have a much smaller lung-capacity. The curves for reaction-time gave the most positive results showing that the brighter the child the more quickly he is able to act. In discrimination, the same relation is noticeable but to a less degree.\nThe bright children and those of average ability, as judged by the teachers, are about equal in the length of time required to discriminate but the dull ones require a somewhat longer time at all ages with the exception of 9, 11 and 13. The difference here between the classes is not so great owing probably to the fact that it involves a smaller element of reaction-time which shows the most marked difference. In turning to the last one, viz : time-memory, it may be said in general that the brighter the child the more accurate his sense of time. It is impossible to say that this is the case with all ages, because the curves, as can be seen, cross and re-cross so frequently as to be of but little value further than to indicate the relation of the three grades in a very general way.","page":94},{"file":"p0095.txt","language":"en","ocr_en":"95\nMental and physical development of school-children.\nComparisons with the results of other investigators.\nOwing to the limited amount of investigation on the mental development of school-children hut little can be said as to how my mental tests agree with other investigations. For the purely physical tests, weight, height and lung-capacity, more material presents itself. For purposes of comparison with the first two\u2014weight and height\u2014 I have chosen the results of Bowditch1 2 of Boston and of Peckham\u2019 of Milwaukee. The weights of the children in both these investiga-\nTable XIII.\nComparative weights of Boston, Milwaukee and New Haven school-children.\nAge. B\tM NHa NHp\nBoys.\n6\t45.17\t44.81\t47.86\t46.8\n7\t49.07\t49.10\t52.08\t51.2\n8\t53.92\t53.81\t56.49\t52.5\n9\t59.23\t59.46\t61.69\t60.0\n10\t65.30\t65.35\t68 31\t68.4\n11\t70.18\t70.92\t75.57\t70.8\n12\t76.92\t76.08\t83.25\t82.3\n13\t84.84\t84.89\t90.95\t88.0\n14\t94.91\t95.76\t97.45\t91.7\n15\t107.10\t109.05\t109.95\t110.0\n16\t121.01\t122.06\t126.03\t127.0\n17\t127.49\t130.35\t126.70\t130.0\nB, weight of Boston school-children in pounds.\nM, weight of Milwaukee school-children\nB\tM NHa NHp\n------ Girls.------\n43.23\t43.12\t46.92\t44.3\n47.46\t46 97\t49.65\t50.4\n52.04\t50.87\t53.32\t53.0\n57.07\t56.44\t59.27\t58.8\n62.36\t62.45\t66.09\t62.7\n68.84\t68.84\t72.35\t10.0\n78.31\t77.82\t86.09\t84.5\n88.65\t87.96\t92.97\t92.0\n98.43\t97.64\t97.15\t98.0\n106.08\t105.87\t103.06\t104.0\n112.03\t110.58\t111.41\t113.0\n115.53\t113.32\t118.45\t113.1\nNHa, weight of New Haven school-ehil-\t\t\t\ndren in pounds\u2014arithmetical averages. NHp, weight of New Haven school-chil-\nin pounds.\ndren in pounds\u2014median values.\ntions as well as in mine were taken in ordinary clothes. My original calculations were made by the method of median values and the curves previously given are plotted upon this method. Since the results of both Bowditch and Peckham were obtained by arithmetical averages, for sake of comparison of the two methods, and also for comparison of localities, I recalculated my results by arithmetical\n1\tBowditch, Growth of children, VIII. Ann. Bept. State Board Health Mass., 301, Boston 1817.\nBowditch, Growth of children, X. Ann. Bept. State Board Health Mass., 35, Boston 1879.\nBowditch, Growth of children studied by Galton's method of percentile grades, XXII. Ann. Rept. State Board Health Mass., 479, Boston 1891.\n2\tPeckham, Growth of children, VI. Ann. Bept. State Board Health Wisconsin, 28, Milwaukee 1881.","page":95},{"file":"p0096.txt","language":"en","ocr_en":"96\nJ. A. Gilbert,\naverages. Notwithstanding the protest of Peckham against the median, in all mental tests, at least for getting a result for each child, it is far preferable to the arithmetical averages.\nPeckham found that Milwaukee children were heavier and taller than Boston children. New Haven children are shown by my results to be still heavier than either of the other two. The comparative weights in pounds are to be found in table XIII and also\nFig. 30. Chart XXV.\nLower curves for weight.\nTJpper curves for height.\n---------Boston boys.\n.........Milwaukee boys.\n---------New Haven boys.\n---------New Haven boys\u2014median values.","page":96},{"file":"p0097.txt","language":"en","ocr_en":"Mental and physical development of school-children. 97\nin graphic form in charts XXY and XXYI. As no relation between the arithmetical averages and median values was considered above, I have inserted here the curve of median values, as well as that of arithmetical averages. Ages are at the bottom ; the figures to the left indicate height in inches ; those to the right indicate weight in pounds.\nThe height of the children in my tests was taken with shoes ; those of Bowditch and Peckham were taken without shoes. After subtracting the height of an average heel of a shoe, which is about 1 inch, the New Haven children are still taller than those of Boston and Milwaukee. The results for height are recorded in table XIV and charts XXV and XXVI.\nTable XIY.\nComparative heights of Boston, Milwaukee and New Haven school-children.\n\u00c2ge.\tB\tM\tNHa\tNHp\n\t\t73\t(\t\t\n\t\t\t\t\n6\t43.75\t44.08\t45.2\t45.0\n7\t45.74\t46.09\t47.4\t47.1\n8\t47 76\t48.05\t49.0\t48.9\n9\t49.69\t50.00\t51.3\t51.2\n10\t51.68\t51.85\t53.0\t53.0\n11\t53.33\t53.76\t56.7\t55.9\n12\t55.11\t54,98\t57.2\t57.0\n13\t57.21\t57.47\t59.2\t58.8\n14\t59.98\t59.89\t60.4\t59.3\n15\t62.30\t62.34\t63.1\t62.8\n16\t66.00\t65.07\t66.7\t63.7\n17\t66.16\t66.60\t67.1\t66.1\nB, height of Boston school-children in inches.\nM, height of Milwaukee school-children in inches.\nB\tM NHa NHp\n------- Girls.------\n43.35\t43.78\t45.0\t44.9\n45.52\t45.93\t46.9\t46.9\n47.58\t47.59\t48.8\t48.4\n49.37\t49.81\t61.1\t50.8\n51.34\t51.89\t53.2\t52.8\n53.42\t53.80\t54.1\t54.6\n55.88\t56.47\t58.3\t57.9\n58.16\t58 68\t59.6\t60.4\n69.94\t60.50\t60.7\t61.4\n61.10\t61.69\t62.2\t62.5\n61.59\t62.16\t62.8\t62.5\n61.92\t62.91\t63.8\t63.6\nNHa, height of New Haven school-children in inches\u2014arithmetical averages. NHp, height of New Haven school-children in inches\u2014median values.\nThis difference in weight and height is very likely due to the smaller proportion of foreigners included in my results. American-born children are taller and heavier than foreign-born children.1\nSo far as the relation of growth of different ages is concerned, the same general laws appear in my results as those obtained by Bow-ditch and Peckham.\t1\nIt is interesting to notice the effect of the private-school gymnasium upon the development of lung-capacity. Table XY and chart XXVII\n1 Bowditch, Growth of children, VIII. Ann. Kept. State Board Health Mass., 307, Boston 1817.\n7","page":97},{"file":"p0098.txt","language":"en","ocr_en":"98\nJ. A. Gilbert,\nrepresent a comparison of my results taken in public schools with the results of Anderson, taken in private-schools near New York. His pupils underwent a daily training in the gymnasium. The boys in his results start at 6 better than those of the same age in my results. They also develop more rapidly. No loss at puberty is traceable, however, in his results similar to that shown in mine. His results extend only to 15 years of age. At this age private-school boys had a lung-capacity of 205 cubic inches; public-school boys by my results only had a capacity of \u00ce\u0178O.S cubic inches, and only 202.5 cubic inches a1\\l7, which is 2.5 cubic inches less than private-school boys had at 15. In girls the difference is even more noticeable, for at 6 the girls\nFig. 31. Chart XXVI.\nLower curves for weight.\nUpper curves for height.\n----------Boston girls.\n.......... Milwaukee girls.\n----------New Haven girls.\n----------New Haven girls\u2014median values.","page":98},{"file":"p0099.txt","language":"en","ocr_en":"Mental and physical development of school-children.\n99\nTable XY.\nComparative lung-capacities for public- and private-school children.\nAge.\tP\tNHa\tNEp\tP\tNHa\tNHp\n\t\t\t\t\t\t\n\t\t\t\t\t\t\n6\t64\t57.1\t56.0\t35\t49.2\t50.0\n7\t80\t65.6\t66.0\t40\t58.9\t54.0\n8\t88\t71.8\t73.0\t\u2022 48\t64.2\t66.0\n9\t106\t82.7\t83.0\t65\t73.4\t72.5\n10\t124\t92.8\t91.5\t80\t80.3\t82.0\n11\t144\t106.3\t104.0\t106\t83.6\t83.0\n12\t150\t117.2\t. 113.5\t125\t104.6\t104.0\n13\t168\t124.4\t120.0\t136\t108.1\t105.0\n14\t188\t120.4\t125.0\t150\t107.8\t105.0\n15\t205\t170.3\t161.0\t155\t116.3\t116.0\n16\t\t189.3\t187.0\t\t\t119.9\t115.0\n17\t\t\t202.5\t204.0\t\t124.0\t118.5\ng-capacity of New York\t\t\tprivate-\tNHp, lung-capacity of New Haven\t\t\nschool children.\nNHa, lung-capacity of New Haven public-school children\u2014arithmetical averages.\nschool children\u2014median values.\nPio. 33. Chart XXVII.\n----------\u2014 Private school boys.\n..........Private school girls.\n----------Public school boys.\n----\u2014-----Public school girls.","page":99},{"file":"p0100.txt","language":"en","ocr_en":"100\nJ. A. Gilbert.\nat private schools have a smaller lung-capacity but develop so rapidly as at 10 years of age to equal those of public schools. Thereafter the rapid development continues so that at 17 they have attained 155 cubic inches while my results only show 116.3 cubic inches for public-school girls; even at 17, public-school girls have only 124 cubic inches capacity, which is 31 cubic inches less than that of private-school girls at 15. The curves of chart XXVII show an enormous difference between the two classes of children. There is added, however, a note to Andebson\u2019s table : \u201c It cannot be said of them that they indicate just what the averages should be.\u201d The results of this table, however, were averages of about 600 children of each age.\nIn chart XXVII the ages are at the bottom and the figures at the left indicate the lung-capacity in cubic inches.","page":100}],"identifier":"lit28770","issued":"1894","language":"en","pages":"40-100","startpages":"40","title":"Researches on the mental and physical development of school-children","type":"Journal Article","volume":"2"},"revision":0,"updated":"2022-01-31T13:15:09.746796+00:00"}