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{"created":"2022-01-31T13:29:13.432430+00:00","id":"lit28736","links":{},"metadata":{"alternative":"Studies from the Yale Psychological Laboratory","contributors":[{"name":"Scripture, Edward W.","role":"author"}],"detailsRefDisplay":"Studies from the Yale Psychological Laboratory 4: 89-139","fulltext":[{"file":"p0089.txt","language":"en","ocr_en":"ELEMENTARY COURSE IN PSYCHOLOGICAL MEASUREMENTS.\nBY\nE. W. Scripture.\nOwing to the newness of experimental psychology its methods of instruction are still matters which must be determined by trial. Sanford 1 has developed a course of simple laboratory experiments, but otherwise the problems of systematized laboratory instruction remain unsolved. A very important problem is that of systematic courses in psychological measurements. Among such courses there must be an elementary one. As the results of my experience of five years in trying to develop such a course may be of use, I will illustr\u00e2t^ the methods employed by describing some of the exercises.\nThe aim of this elementary course is similar to that of the elementary courses in chemistry and physics, namely : education and instruction of the general student. It is intended to be part of the regular college education; among elective courses it is specially chosen by students intending to study medicine or to teach. It is a noteworthy fact, however, that the subject matter attracts students who take no other laboratory courses of any kind.\nI he student makes his own text-book with the aid of : i. sets of mimeographed instructions which are given out at each exercise ; 2. illustrations in the form of prints from blocks, blue-prints, tracings, etc.; 3. references for applications and further reading to some psychological work.\nI he following are copies of some of these mimeograph-sheets with explanatory remarks. The \u201cPreliminary notes\u201d are given out with the first exercise. The first few exercises are of moderate difficulty, but they occupy the inexperienced student for about two hours each. The later exercises are adapted to the increased skill of the student. Since the applications and the bearings of the exercises can be made evident only in a general course on experimental psychology, the laboratory course is taken only in connection with the lecture course. Some idea of the verbal instruction that is given to the pupils and of what they hear and see in the lecture course can be obtained by referring to my New Psychology by means of the topics in the index.\nI he following exercises are selections from a set of thirty now in use.\n'Sanford, Laboratory Course in Experimental Psychology, I\u2019oston, 1895.\n89","page":89},{"file":"p0090.txt","language":"en","ocr_en":"90\nE. IV. Scripture,\nPreliminary notes.\nA.\tObjects of the course.\u2014Practical training in (i) observation, (2) manipulation, (3) computation, (4) deduction, (5) criticism. Elementary acquaintance with (a) methods of experimentation, (b) methods of measurement, (r) construction and use of apparatus, (</) special psychological methods. Thorough appreciation of the three fundamental properties of scientific work: (1) accuracy, (2) brevity, (3) neatness.\nB.\tArrangement of the class.\u2014The class is divided into groups of two persons each. Any student who wishes to do so 'may select the other member of his own group. One group begins with Ex. I.; another with Ex. II., etc. At the next exercise the group that has had Ex. I. takes Ex. II.; the one that has had Ex. II. takes Ex. III.; etc. At each succeeding exercise a group takes the exercise that follows in numerical order.\nC.\tInstructions to the student.\u2014Look at the index on the bulletin board ; opposite the number of the exercise for the day you will find the number of the room in which it has been set up. On the table bearing the number ot your exercise you will find two sets of printed instructions, one for each person. Compare your set with another set marked in red \u201cCorrected Copy,\u2019\u2019 and make any changes that have been indicated in red ink. You will also find all the apparatus of the exercise called for under \u201c Needed.\u201d It is set up ready for use. Begin by reading the first paragraph of the instructions and applying it to the apparatus. Take the following paragraphs singly.\nAfter carefully studying the apparatus and its connections take it down and set it up again. In performing the experiments one person serves as experimenter, the other as subject. The places are then exchanged and the experiments are repeated. The subject is. to know nothing about the results obtained on himself. The record must be made on the printed blanks.1 When finished, these records are to be handed to the instructor. They will be marked, the mark being given to the experimenter (who has prepared the record).\nThe fundamental requirements for the records are accuracy and neatness. See that you understand all the \u201cPoints to be noted.\u201d If not, consult the instructor. Also see that you can answer the \u201c Questions.\u201d It is intended in many cases that you shall get the answers directly from the instructor. The student will be held responsible on all these points. At the end of the exercise place all apparatus in the condition in which it was found. Do not leave until the instructor has inspected and approved your work. When the whole class has finished an exercise, the\n1A specimen blank will be sent to any one who will ask for it.","page":90},{"file":"p0091.txt","language":"en","ocr_en":"Elementary course in psychological measurements.\n91\nfinal results for each student will be placed in a table and a copy of the table will be handed to the student, together with his record. This \u201c summary \u201d and the original records are tobe kept by the student. The examination at the end of the term will include some practical work.\nGeneral instructions for computation.\nIf the method of measuring is sufficiently fine, the results in a set of measurements will differ from each other. The average of these is the most probable value of the quantity. Let the results of a set of n measurements on the same quantity under constant conditions be mv m2,\n. . ., mn. The average is\na = m\u2018 + mt +\u2022\u2022\u2022+\u201d*\u00bb n\nIt is desirable to have some expression of the uncertainty of the result a, and this is given by the \u201cprobable error.\u2019\u2019 The probable error is that error which is as likely as not to be exceeded, or, if r be the probable error of a, it is just as likely that the true value of the quantity lies between a \u2014 r and a + r as that it lies outside those limits. Thus, if the average be written a \u00b1 r the probable error r furnishes an index of the uncertainty of a ; the smaller the value of r, the greater is the precision of the average a. In works on the theory of errors it is shown that the probable error r is given by the expression\nr= 0.6745\nJ3'\n+jv\u00b1\nn(n \u2014\n\ni)\nin which vv v2, ... , vn are the residuals found by subtracting the individual measures from the average, thus vx = a \u2014 ,\nAs an example let there be ten measurements made with equal precision upon a single quantity giving the results m1 = 10, m2 = 14, etc. The computation is as follows :\n1)1\tV\tV*\t\n10\t1.2\t1.44\t\n14\t2.8\t7.84\t\n16\t4.8\t23.04\t\n8\t3-2\t10.24\tP'0.91 ^ 0.95\n14\t2.8\t7.84\t\n6\t5*2\t27.04\t\n12\t0.8\t0.64\t2/}X 0.95=0.63\n10\t1.2\t1.44\t\n12\t0.8\t0.64\t\n10\t1.2\t1*44\ta= II.2 \u00b1 0.6\n10)112\t\t9)81.60\t\na = 11.2\t\t10)9.07\t\n\t\t0.91\t","page":91},{"file":"p0092.txt","language":"en","ocr_en":"92\nE.\nIV. Scripture,\nHere the average is 11.2 and its probable error is 0.6 ; that is, it is as likely that the true value lies between 10.6 and 11.8 as that it is less than 10.6 or greater than 11.8. If the observations had been such as to have given a = 11.2 \u00b10.9 the average 11.2 would be much less precise than in the above case.1\nTable of squares.\nI\tX i\t21\t441\t41\t1681\t61\t3721\t8l\t6561\n2\t4\t22\t484\t42\t1764\t62\t3844\t82\t6724\n3\t9\t23\t529\t43\t1849\t63\t3969\t83\t6889\n4\tl6\t24\t576\t44\t1936\t64\t4096\t84\t7056\n5\t.25\t25\t625\t45\t2025\t65\t4225\tS5\t7225\n6\t36 '\t26\t676\t46\t2116\t66\t4356\t86\t7396\n7\t49\t27\t729\t47\t2209\t67\t4489\t87\t7569\nS\t64\t28\t784\t48\t2304\t68\t4624\t88\t7744\n9\t81\t29\t841\t49\t24OI\t69\t4761\t89\t7921\nIO\tIOO\t3\u00b0\t900\t5\u00b0\t25OO\t70\t4900\t90\t8100\nII\tI 21\t31\t961\t51\t2601\t71\t5041\t91\t8281\n12\t144\t32\tIO24\t52\t2704\t72\t5184\t92\t8464\n\t169\t33\t1089\t53\t2809\t73\t5329\t93\t8649\n14\t196\t34\t1156\t54\t2916\t74\t5476\t94\t8836\n15\t225\t35\t1225\t55\t3025\t75\t5625\t95\t9025\nl6\t256\t36\t1296\t56\t3130\t7\u00d6\t5776\t96\t9216\n17\t289\t37\t>369\t57\t3249\t77\t5929\t97\t9409\t,\nl8\t324\t3\u00ab\t1444\t58\t33^4\t78\t6084\t98\t9604\n19\t361\t39\t1521\t59\t3461\t79\t6241\t99\t9801\n20\t400\t40\t1600\t60\t3600\t80\t6400\tIOO\tIOOOO\nExercise I.\u2014Threshold of touch.\n(Needed : touch-weights, cross-section paper, flexible ruler.)\nApparatus.\nThe set of touch-weights consists of small cork discs weighing from 2m* upward ; they are attached by fine threads to small handles.2 The weights are marked on the handles.\nExperiments.\nThe subject, with eyes closed, places his left hand, palm upward, on his knee. He is to tell when he feels himself touched. The experimenter gives the warning \u201cReady\u201d and, about 2 to 5 sec. later, lowers the lightest disc gently till it touches a certain spot on the skin, e. g.,\n11 am under great obligation to Professor Mansfield Merriman (author of \u201cA Textbook on the Method of Least Squares \u201d ), of Lehigh University, for assistance in presenting the methods of computation.\n* See Fig. 57 of Scripture, Thinking, Feeling, Doing.","page":92},{"file":"p0093.txt","language":"en","ocr_en":"Elementary course in psychological measurements.\n93\nthe tip of the index finger; the disc is allowed to rest on the skin for about Is. The experiment is then repeated with the next heavier disc, and then with the other discs in succession. A check is made in the appropriate column of the record blank for each disc as it is felt. The whole experiment is repeated io times.\nAfter the whole set of experiments has been made the number of the first disc felt in each experiment is recorded in the column headed mx, and the number of the disc beyond which all were felt in the column headed mr The average is calculated for each set. The former of the two averages may be called the lower threshold, the other the upper one.\nSpecimen record.\nTitle of investigation, Threshold of Apparatus, Touch-weights, touch.\tDate, October 5, 1896.\nExperimenter, T. C. McGraw.\tUnit of measurement, milligram.\nExperimented on, W. K. Chisholm.\nWeight\t\t2\t468\t10\t12\t14\tl6\t18\t20\t22\t24\t26\t28\t3\u00b0\nExper. No.\tI\t\t\t\t+\t+\t1\t4-\t+\t+\t-L.\t+\t+\t\n<< (<\t2\t\t\t\t\t+\t+\t+\t+\t4-\t+\t+\t+\t+\nIt\tn\t3\t\t\t\t\t\t+\t\t+\t+\t\t+\t+\t+\nll\t((\t4\t\t\u2022 \u2022 +\t\t\u2022b\t+\t\t+\t+\t+\t_L\t+\t+\t+\nII\tll\ts\t\t\t\t\t4-\t+\t+\t4-\t+\t+\t+\t-i- 1\t+\nil\til\t6\t\t+ 4-\t+\t+\t+\t+\t+\t+\t+\t+\t+\t+\t+\nil\til\t7\t\t\t\t4-\t+\t+\t\t+\t\t\t+\t+\t+\nil\ttt\t8\t\t\t4-\t\t+\t+\t+\t+\t+\t+\t+\t+\t+\nli\tli\t9\t\t\t\t+\t+\t+\t\t+\t+\t+\t+\t+\t+\nil\til\tIO\t\t\t+\t4-\t\t+\t+\t\t+\t+\t+\t+\t+\nTimes felt\t\tO\t0 12\t4\t6\t8\t9\t9\t9\t9\t10\t10\t10\t10\nm,\t\t''1\t?\u2022 2 M\t\t\t\t\t\"h\t\tv.t\t\t\t2\t\nIO\t\t1.2\t1.44\t\t\t\t\tIO\t\t50\t\t25-\tOO\t\n14\t\t2.8\t7.84\t\t\t\t\t14\t\t1.0\t\t1.\t\t\nl6\t\t4-8\t23.04\t\t\t\t\t16\t\t1.0\t\t1.\t\t\n8\t\t3-2\tIO.24\t\t\t\t\t18\t\t30\t\t9-\t\t\n14\t\t2.8\t7.84\t\t\t\t\t14\t\t1.0\t\tI.\t\t\n6\t\t5-2\t27.04\t\t\t\t\t6\t\t9.0\t\t81.\t\t\n12\t\t0.8\t0.64\t\t\t\t\t24\t\t9.0\t\t81.\t\t\nIO\t\t1.2\t1.44\t\t\t\t\t14\t\t1.0\t\tI.\t\t\n12\t\t0.8\t0.64\t\t\t\t\t12\t\t30\t\t9-\t\t\nIO\t\t1.2\t1.44\t\t\t\t\t22\t\t7-0\t\t49.\t\t\nII.2\t\t\t9)81.60\t\t\t\t\t15.0\t\t\t9)252.\t\tOO\t\n\t\t\t10)9.07\t\t\t\t\t\t\t\t10\t)28.\tOO\t\n\t\t\tO.9I\t\t\t\t\t\t\t\t\t2.\t80\t\n\t\ti/ 0.91\t= 0.95\t\t\t\t\t\t1/2.\tSo =\t1.67\t\t\t\n\t2/sX 0.95 = 0-63\t\t\t\t\t\t\tXX\t\t1.67 =\t= 1.11\t\t\t\n\ta\t= u.\t2 \u00b1 0.6\t\t\t\t\t<h =\t\t15.0\ttu\t\t\t","page":93},{"file":"p0094.txt","language":"en","ocr_en":"94\t\u00a3. IV. Scripture,\nTheoretical considerations.\n0.75 -\n0.50\n0.25 -\n8\t10\t12 14 16 18 20 22 .24- 26 28 30\nThere is evidently a relation between the weight of the disc and the number of times it is felt. Let the number of times be expressed as a fraction, e. g., a percentage, of the total number of experiments, and suppose the number of experiments to have been very large with the same results. Let this fraction, or percentage, be expressed in the form of a curve, where x denotes the weight of the disc and y denotes the relative frequency with which it was felt. The curve will be one of the forms shown in the accompanying figure. Lor an extremely sensitive person the curve will be very steep, like that to the left ; for persons of less sensitiveness it will be flatter.\nThe experimenter is to plot the curve for his own record. The plotting is done on cross-section paper ; this is paper ruled with horizontal and vertical parallel lines. On one of the horizontal lines lay off the scale of weights 2, 4, etc., with any convenient distance as the unit. On one of the vertical lines lay off a scale of percentages with any convenient distance as the unit. For each weight count upward above its place on the horizontal axis a number of spaces corresponding to its percentage ; the ruling of the paper into spaces in groups of 5 and 10 make it possible to do this rapidly. Connect each dot to the following one by a straight line. The fluctuations of this line are due to irregularities in the experimenting and to the smallness of the number of experiments. The true relation of percentage to weight will be more closely indicated by a smooth line, which can either be drawn by the free hand or by adjusting a flexible ruler so as to","page":94},{"file":"p0095.txt","language":"en","ocr_en":"Elementary course in psychological measurements.\n95\npass smoothly among the dots. Owing to the fact that the number of experiments was only io instead of an infinite number, the actual curve will differ from the theoretical one ; with ioo or 1000 experiments it would approach the theoretical one more closely.\nTo compare the degrees of sensitiveness of different persons, two quantities can be used : either the disc that corresponds to acertainpercentage, say 75%, or the percentage for a certain disc. To use either effectively a large number of experiments would be required ; the calculation of the average of the two thresholds as found above gives a sufficiently accurate figure. It is evident that the higher the threshold the lower the sensitiveness ; in fact, probably the only proper definition of \u201csensitiveness\u201d is \u201cthe reciprocal of the threshold.\u201d \u201cReciprocal\u201d of a quantity means i divided by that quantity. Thus, if two persons have thresholds of a' and a\" respectively, their degrees of sensitiveness will be i/a' and i/a\".\nPoints to be noted.\ni. Note that the uncertainty of the threshold is indicated by the size of the probable error. 2. In the curves given in the figure, y is said to be a function of x. This is expressed by y =/(x). The particular curves assumed in the figure are taken from the science of probabilities.\nQuestions.\ni. How would you define \u201c threshold \u201d so as to fit all kinds of sensations? 2. What are presumably some of the mental conditions of the subject that contribute to his probable error?\nExercise II.\u2014Skin space.\n(Needed: two \u00e6sthesiometers, millimeter scale.)\nApparatus.\nIn its simplest form the \u00e6sthesiometer is a pair of dividers with blunt points. The points arc made of hard rubber, in order to eliminate sensations of temperature.\nExperiments.\nA. Open the \u00e6sthesiometer several centimeters. Touch the two points simultaneously to the cheek in a vertical direction ; they will be felt as two. Repeat the experiment, reducing the distance between the points each time. To maintain the unprejudiced condition of the subject, insert occasional experiments with only one point touched to the skin. The subject is to state each time whether he feels one point or two. Con-","page":95},{"file":"p0096.txt","language":"en","ocr_en":"96\nE. /V. Scripture,\ntinue the experiments till a mistake is made in feeling two points as one. Now apply the \u00e6sthesiometer to the scale and record the distance between the points. Repeat the measurement ten times. Find the average and average variation.\nB.\tRepeat the experiments of A on the back of the neck in a vertical direction.\nC.\tAdjust one \u00e6sthesiometer to 30\"\"\" as a standard. Apply it for a moment to the cheek of the subject. Adjust the other \u00e6sthesiometer to an arbitrary distance. Apply it likewise to the cheek. The subject is to say whether the second distance was greater or less than double the first. According to the answer adjust the second \u00e6sthesiometer differently and repeat the experiment. Proceed as in A, the first \u00e6sthesiometer being kept at the constant distance of \u00dfo1\"\u201c and the second being gradually changed till a judgment of \u201c equal to double the first\u201d is obtained. Take ten records.\nSpecimen record.\nABC\n1)1\tV\tV2\tm\tV\tV*\tm\tV\t'A\n23\t0.8\t0.64\t31\t4-3\t18.49\t41\t2.6\t6.76\n21\t2.8\t7.84\t32\t3-3\t10.89\t39\t4.6\t21.16\n25\t1.2\tM4\t3\u00b0\t5-3\t28.09\t40\t3-6\t12.96\n23\t0.8\t0.64\t40\t4-7\t22.09\t45\t2.4\t5.76\n26\t2.2\t4.84\t45\t9-7\t94.09\t48\t4-4\t1936\n21\t2.8\t7.84\t38\t2.7\t7.29\t45\t1.4\t1.96\n27\t3.2\t10.24\t31\t4-3\t18.49\t40\t3-6\t12.96\n26\t2.2\t4.84\t31\t4-3\t18.49\t49\t5-4\t29.16\n23\t0.8\t0.64\t41\t5-7\t32-49\t51\t7-4\t54-76\n2.3\t0.8\t0.64\t34\ti-3\t1.69\t38\t5.6\t31-46\n23.8\t9)39.60\t35-3\t9)252.10\t\t43-6\t\t9)196.20\n\t10)4.40\t\t10)28.01\t\t\t\t10)21.80\n\t0.44\t\t\t2.80\t\t\t2.18\n1/0.44 = 0.66\t\t1/2\t.80 -1\t\u202267\t1/\t2.18 =\t= 1.48\nYs X\u00b0-66 = 0.44\t\tYs x 16.73 =\t\t1.11\t73 X 1*48\t\t= 0.99\na =\t23.8*0.4\ta =\t35-3 +\t1.1\ta =\t= 43-6\t\u00b1 1.0\n\t\tPoints\tto he\tnoted.\t\t\t\ni. Note that the results depend somewhat on the skillfulness of the experimenter. 2. Note that psychologically double does not necessarily correspond to absolutely double.\nQuestions.\nI. What improvements would you suggest in the apparatus and the method of experimenting? 2. How would you express the relation between space on the cheek and space on the neck in your experiments ?","page":96},{"file":"p0097.txt","language":"en","ocr_en":"Elementary course in psychological measurements.\t. 97\nExercise III.\u2014Arm-space.\n(Needed : arm-space board, cross-section paper.)\nApparatus.\nIn the arm-space board1 a wooden scale carries along its upper edge a small glass rod. At the zero point in the middle there is a fixed metal plate. On each side there is a movable slide carrying an adjustable pointer. Before the experiments the pointers are pushed forward as far as possible.\nExperiments.\nA.\tThe apparatus is placed on a table with the scale away from the subject. The subject, seated with eyes closed or covered, places his forefingers against the zero-plate, one on each side.\nB.\tThe experimenter moves up the two slides to the fingers till they press gently. The pointers strike the zero-plate and are pushed back automatically. This eliminates the errors due to the width of the finger, as all readings are to be taken from the end of the pointer.\nC.\tThe subject places himself directly in front of the zero-mark and closes his eyes. The experimenter places the left-hand (referring to the subject) slide at a certain distance dv The right-hand slide is moved out of the way. The subject moves his left fore-finger evenly outward till it strikes the slide, and then returns it to zero. The experimenter quietly moves the slide out of the way, and the subject then moves his finger again till it seems to be in the same place as before. The experimenter now moves the slide up till it touches the finger and reads the record at the end of the pointer. The tenths of a centimeter are estimated by the eye. The result in millimeters is placed in the column mx of the record blank.\nSome other distance d,t is now chosen and the experiment is repeated, giving a result mv Likewise d3, dt and d,t are used. The five distances are chosen as follows: 100, 200, 300, 400, 500 millimeters. The experiments are performed in this order : from d2 to d.t, from dh to dv from ds to dv from </, to dy Eight complete sets are made, giving eight records for each distance. Find the averages and probable errors. Denote the averages by a,, at, . . . , a.. The difference between the given distance and the average result for that distance is the constant error of the estimate. There are thus five constant errors, r, = at \u2014 d\u201e c2 = a2 \u2014 d2, . . . , c5 = a. \u2014 dy The constant error expresses the average inaccuracy in reproducing the given distance. The probable error expresses the irregularity. Both these quantities depend on the values of d.\n1 New Psychology, l'ig. 44.\n7","page":97},{"file":"p0098.txt","language":"en","ocr_en":"9S\nE. IV. Scripture,\nFie. 14.\nTo make plain the laws of dependence, the results are to be expressed in two curves y = / (.v) and Y = F (.v) where x =dv d2, . . . , d. and y and V are the constant errors and the probable errors. To draw these curves a certain distance is selected on the cross-section paper to represent dv and the points //,, //,, . . . , ds are laid off on the horizontal axis. Any convenient distance is chosen for_y = 1 and the ordinates for l',, yt, ... are erected. On joining the tops of these ordinates by a line the curve of results is indicated. The relation of Yv V2, . . . , Ys to dv dt, . . . , dt is indicated in a similar manner.\nSpecimen record.1\n*j=\tIOO\t</..=\t200\t4\t= 3\u00b0\u00b0\t\tdi = 400\t\t<4= 500\n\t\t\tv.p\tm3\t-2 4 3\t\t7, 2 \u20184\t\u00bb/.\tVr*\n105\t79.21\t193\t6.25\t267\t334-89\t355\t723.61\t454\t1253.16\n116\t26.01\t197\t2.25\t281\t18.49\t381\to.Si\t494\t21.16\nno\t0.S1\t189\t42- 25\t297\t136.89\t399\t292.41\t473\t268.96\n107\t15.21\t201\t30.25\t285\t0.09\t398\t259.21\t505\t243-36\n108\t8.41\t195\t0.25\t2S0\t28.09\t371\t118.81\t487\t5.76\nII5\t16.81\t195\t0.25\t269\t265.69\t393\t123.21\t500\t112.36\n114\t9.61\t196\t0.25\t3\u00b05\t388.09\t408\t681.21\t507\t309.76\n112\t1.21\t*97\t2.25\t298\t161.29\t350\t1017.61\t495\t3136\n8)887 7)157.288)1564 7)84.008)2282 7)1333-528)3055 7)3216.88 8)3915 7)2245.88 110.98)22.47^ 195.5 8)12.00 285.3 8)190.39 381.0 8)459.55 489.4 8)320.84 2.81\t1.50\t23.79\t57.44\t40.H\n1 The student need not record the residuals v but should at once write the squares v2.","page":98},{"file":"p0099.txt","language":"en","ocr_en":"Elementary course in psychological measurements.\n99\n/ 2.81 = 1.68 1.68 = 1.12 ,(, = 110.9* 11 <-, = +10.9\n/1.50= 1.22 ^X'. 22 = 0.81 a., = 195.5 \u00b10.8 <j = \u2014 4.5 = o. 8\n^23.79 = 4-SS\n81\t%X 4-88 = 325\n'\u20228\ta3 = 285.3 \u00b13-3\n;, = i.i\nq = \u2014 18.1 9 = 5-\u00ab c=f(d)\nFor d- IOO,\tc = -(- 11\nl/S7-44= 7.58\n2AX 7-58 = 505 ,(4 = 381.9 \u00b15.1\nK40.il =6.33 5^X6.33 = 4-22 <7. = 489.4\t4. 2\nr5 = \u201410.6\nr = /-(d)\nd= 200,\tr\t=\u2014\t7\n,7=300,\tr =\u201415\n,7=400,\tc\t= \u201418\n,7=500,\te\t=\u2014\tII\nFor,7= 100,\tr\u2014l.i\n,7=200,\tr = o.8\n,7=300,\t>- = 3-3\n(7=400,\tc= 5-1\n^=500,\tc = 4.2\nPoints to be noted.\ni. The method of getting tenths by the eye is in this case convenient and accurate. 2. Automatic elimination of a constant error (width of the finger) from the readings. 3. Equalizing the influences of fatigue, practice and'other progressive errors by changing systematically the order of the experiments.\nQuestions.\ni. If the probable errors were directly proportional to the values of ,/, what form would the curve take? 2. What would a recorded constant error or a probable error of o mean ?\nExercise IV.\u2014Memory.\n(Needed : two sets of geometric figures, two bands of syllables, two bands of colors, revolving cylinder, screen and metronome.)\nApparatus.\nThe metronome is a convenient pendulum arrangement for marking off intervals of time when great accuracy is not required. The clockwork is wound by the screw at the side ; the cover is removed from the front ; the pendulum is released and the weight is set at sixty. When started, the metronome will mark off seconds.\nThe two cards for the experiments with figures are in separate envelopes, one for each subject. The experimenter takes the envelope containing the card which he is to use on the other person as subject. The subject must not see beforehand the card that is to be used on him.","page":99},{"file":"p0100.txt","language":"en","ocr_en":"IOO\nE. 1V. Scripture,\nThe revolving cylinder is moved by clockwork, which is kept wound by the appropriate key. It is started by releasing the brake. It revolves once in 10 seconds.1\nOne band of syllables and one band of colors will be found in each envelope with the card mentioned above.\nA screen is placed before the cylinder so that only one syllable or color is seen at a time.\nExperiments.\nSt. A pad of blank paper is placed before the subject. The experimenter holds the card with figures and at a beat of the metronome he shows it to the subject, counting o, i, . . . , 10 and turning down the card at 10. The subject immediately tries to reproduce on the blank paper all the figures he saw. The paper is numbered and handed to the experimenter. The card is again shown for 10 seconds and the subject again tries to reproduce the figures. This is repeated until all are reproduced correctly, unless success is not reached before the 15th trial, at which point fatigue generally begins. A record is made of how many were reproduced correctly in shape and arrangement on each trial.\nB.\tThe band of syllables is slipped on the cylinder. When it is set going it exposes one syllable per second through the screen. During the first revolution the subject calls off each syllable as he sees it ; thereafter he tries to call off each syllable just before it appears, correcting himself if wrong. The experimenter notes the number of revolutions performed by the drum. This is continued until all are called off directly or until the 20th revolution. The number of revolutions is recorded.\nC.\tThe band of syllables is replaced by the band of colors and the experiment is repeated. The subject notes and recalls the colors as much as possible by visual memory and does not attempt to name them.\nPoints to be noted.\ni. Difficulty of remembering without making external associations. 2. The prominence of motor and auditory elements in B and C.\nQuestions.\ni. What would be some of the problems of memory that might be answered by the experiments with syllables? 2. What sources of inaccuracy do you notice in the methods of experimenting ?\n1 In case the kymograph is used, it is properly adjusted by the instructor beforehand. The study of the kymograph, which is too difficult for the student at this point, is brought forward in Exercise NTII.","page":100},{"file":"p0101.txt","language":"en","ocr_en":"Elementary course in psychological measurements.\ti o i\nExercise V.\u2014Illusion of length.\n(Needed : illusion board, millimeter measure.)\nApparatus.\nThe illusion board is made as follows. A strip of celluloid is tacked at the corners to a board i foot x 9 inches (30e\"' x 23e'\") large. The opening ABCD is cut in it. Six celluloid strips are prepared, such that they can be slipped under the left-hand edge of larger sheet and appear in the opening with one edge crossing at the middle PQ. Six some-\nFin. 15.\nwhat longer slips are prepared, such that they can be slipped under the right-hand edge and extended past the middle under the shorter slips. The shorter slips bear diagrams of the kind shown to the left in Figure 16 ; the longer ones bear diagrams of the kind shown to the right. Six pairs of slips are used with diagrams of the forms indicated in the following list ; the slant lines are called \u201c angle lines.\u201d\nMark on the card\tab\tc\td\te\tf\nLength of angle-line, in millimeters\t30\t30\t30\t15\t30\t60\nAngle between angle-line and horizontal\t150\t30\u00b0\t6o\u00b0\t30\u00b0\t30\u00b0\t30\u00b0\nThe length of the constant horizontal line is not to be measured until all experiments are completed.\nExperiments.\nAr. The slips marked a are inserted in the manner described. The subject holds the board directly in front perpendicularly to the line of vision at the ordinary reading distance. He moves the longer slip until the two parts of the horizontal line appear equal. He then hands the","page":101},{"file":"p0102.txt","language":"en","ocr_en":"102\nE. JV. Scripture,\nboard to the experimenter, who measures N, records the result, pulls the longer slip out slightly and hands the board back.\nAr The experiment is repeated with PP on the left-hand side.\nBr. The slips marked b are used as in Ar.\nBt. As in Br with JV to the left.\nCr. Slips c ; N to right.\nCv\t\u201c\te;\t\u201c\t\u201c\tleft.\nDr.\t\u201c\td;\t\u201c\t\u201c\tright. \u2022\nDc\t\u201c\td;\t\u201c\t\u201c\tleft.\nEr.\t\u201c\te-,\t\u201c\t\u201c\tright.\nEt.\t\u201c\te ;\t\u201c\t\u201c\tleft.\nEr. \u201c\tright.\n\u2022 Fv \u201c f\\ \u201c \u201c left.\nEach record is made in a separate column on the blanks. The experiments are performed four times in the following order: i. Ar to Et (as in the list above) ; 2. E^o Ar\u2018, 3. Et to Ar; 4. Ar to Er\nComputation.\n1.\tFind the average for each column, writing the results in whole numbers.\n2.\tFind the averages for A, B, etc., thus:\nA = A' \u2014B = B' B\\ etc.1 2\t2\n3.\tMeasure M.\n4.\tFind /, = A \u2014 M, I\u201e = B \u2014 M, etc. Do not disregard the sign.\nThe results /\u201e\tI,, give the amount of the illusion as a function of the\nangle, or f=/(E). The results I\u201e, IK, Tr give the amount of the illusion as a function of the length of the end lines, /= E(S).\nPoints to be noted.\ni. Notice carefully the system on which the experiments are arranged, in order to equalize the effects of progressive errors. 2. Notice that an orderly arrangement of the slips on the table and an appropriate routine in performing the experiments are conducive to the saving of time.\n'Results for 13 students in 1896 were as follows :\nSubject.\tA\t15\tC\tD\tF\tG\t11\tI\t.T\t0\tP\tQ\nA\t90\t95\t83\t84\t71\t81\t84\t81\tSt\t92\t90\t88\nB\t97\t99\t83\t84\t75\t83\t86\t86\t85\t93\t93\t88\nC\t97\t100\t90\t85\t79\t87\t90\t92\t88\t96\t92\t90\nD\t96\t100\t84\tS8\t78\t86\t90\t87\t85\t96\t95\t92\nE\t96\t98\t79\t80\t75\t85\t87\t82\tS3\t92\t92\t86\nF\t97\t96\tSo\t82\t69\t84\t86\t82\t84\t90\t92\t89\n<5o & &","page":102},{"file":"p0103.txt","language":"en","ocr_en":"Elementary course in psychological measurements.\t103\nQuestions.\ni. What are \u201cprogressive errors?\u201d Mention some. 2. Why not omit the experiments underhand Et and substitute in I\u2014/(S) the values from Br and Bl ? 3. How would you compute the results in order to determine the difference in the illusion between iVto the right and N to the left ?\nExercise VI.\u2014Threshold of intensity for sound.\n(Needed : differential audiometer, telephone, battery of 1 A, i. e., of I ampere.)\nApparatus.*\nThe audiometer comprises two primary coils at the ends of a base and a movable secondary coil in the middle. The wires from the battery are brought to the binding posts at one end of the apparatus. The current passes around the one primary coil clockwise and then around the other counter-clockwise. When this current is broken by the key at the other end of the apparatus, a momentary current is aroused by each primary coil in the secondary coil.\nThe telephone is connected with the secondary coil. Place the secondary coil close to one of the primaries ; hold the telephone to the ear and, gently moving the key, note that the induced current produces a sound. Repeat with the secondary close to the other primary.\nSince the primaries are wound in opposite directions the induced currents must be in opposite directions. Consequently the sound diminishes from its maximum loudness at either end to zero at the middle.\nExperiments.\nA.\tThe secondary coil is placed sufficiently near the primary to give a distinctly audible sound. The subject holds the telephone to the right ear and closes the left with the finger. He sits with his back to the apparatus.\nThe experimenter repeatedly interrupts the current by slightly moving the key. The subjects responds whenever he hears the click in the telephone. The secondary coil is slowly moved toward the middle until the subject first loses the sound. The sound can be regained frequently after it has been lost, but this is disregarded. The graduation is in millimeters.\nB.\tThe secondary coil is started at the middle and moved till the subject first hears the sound.\nThe left ear is tested in like manner.\n'A brief description of the simplest form of the lamp battery (see p. 77 ) 's \u00a3\u2019vcn a* this point ; the extra-circuit battery appears in Ex. XV.","page":103},{"file":"p0104.txt","language":"en","ocr_en":"104\nE. IV. Scripture,\nComputation.\nFind the averages for A and B for a set of four experiments alternated so as to equalize progressive errors.\nFind the general average ; denote it by t.\nThese values represent the faintest perceptible sound, or the threshold, under the particular conditionsof the experiment.1\nIf the average value for normal individuals is T, then the subject\u2019s relative deafness can be stated as d = [ or his sharpness of hearing as\nh \u2014 -^\u2014 \u2014 . With this particular apparatus and i amp\u00e8re of current, T= 200 \",m.\nPoints to be noted.\ni. The scale is a purely arbitrary one. 2. The sound is very little influenced by any changes in the current.\nQuestions.\ni. How would you define \u201csensitiveness to sound?\u201d (See Ex. I). 2. What sources of error are possibly present ?\nExercise VII.\u2014Dvnamomf.try ok voluntary action.\n(Needed: finger dynamometer, piston recorder, rubber tube, air valve, simple recording drum, smoking and varnishing arrangements, screw-vise.)\nApparatus.\na. The dynamometer.'1 This consists essentially of two spring-steel rods, rigidly fastened in a base block. These rods can be deflected inward by pressure on two small knobs. The extent of the deflection is indicated on a scale at the ends. This scale has been graduated by actual trial ; the unit is the kilogram.\n'The following results were obtained from 16 students in 1896 ; the unit is the centimeter.\nSubject.\nRight I Left I\n2 See New l\u2019sychology, Figs. 4 and 24.\nt.\tA\t\u00ab\tD\tE\tF\tH\tI\tJ\tK\tL\tM\tO\tP\tQ\tR\tS .\u2022\tVverag\nA\t22\t17\t21\t17\t25\t27\t17\t18\t26\t16\t44\t26\t12\t12\t11\t13\t20\nB\t*9\t27\t27\t23\t25\t29\t19\t23\t25\t18\t36\t27\t14\tII\t19\tIS\t22\nA\t20\t17\t22\t18\t23\t22\t28\t19\t25\t17\t25\t17\tII\tII\t19\t14\t19\nB\t20\t19\t26\t20\t25\t22\t26\t28\t24\tiS\t25\t19\t12\t11\t20\t16\t21","page":104},{"file":"p0105.txt","language":"en","ocr_en":"Elementary course in psychological measurements.\t105\nA glass cylinder is attached to one of the rods of the dynamometer and a rubber piston is connected with the other rod by an aluminum bar. As the rods are pressed together the air of the cylinder is forced out through a rubber tube attached to the bottom. This cylinder is called the receiving cylinder.\nb.\tPiston recorder. At the other end of the tube is the recording cylinder, constructed similarly to the receiver. The piston of the recording cylinder is connected to an aluminum lever which is lengthened by a very light straw rod ending in a fine quill point. As the air, driven out from the receiver, is forced into the recorder, the quill point must repeat on a highly enlarged scale the movement of the rods of the dynamometer. There are various adjustments on the recorder for changing the amplification, for placing the point higher or lower, for making the plane of movement tangential to'the surface of the drum, for adjusting the cylinder, etc.\nEach piston is rendered air-tight by a drop of oil. The valve in the rubber tube serves to let air out or in when it is desired to change the position of the recording point.\nc.\tRecording drum. This is a carefully turned brass cylinder, revolving on an axis. The drum is first placed with its axis horizontal. The end of a sheet of glazed paper is moistened with paste. It is then stretched tightly and smoothly around the drum and the pasted end is lapped over the other one. This makes a tight band of paper around the drum ; no paste should be allowed to get on the drum itself. A gas flame is held beneath the drum so that it deposits soot on the paper ; the drum is slowly turned in order to keep the paper from burning.\nd.\tAdjusting the apparatus. The drum is placed so that its axis is vertical. The quill point of the recorder is brought near the smoked surface by moving the support and by adjusting the screws that hold it. Then the point is brought into light contact with the surface by turning the adjusting screw at the side. The lever should be as nearly as possible at a tangent to the surface of the drum. As the drum is turned, a line is drawn in the smoke by the quill point.\nThe dynamometer is held between the tips of the thumb and index finger; the base block rests lightly in the palm of the hand. A comfortable position is found and the eyes are closed.\nExperiments.\nA. Scale of effort. At the word \u201cOne\u201d from the experimenter the subject presses the dynamometer lightly. At the word \u201c Two \u201d he presses it twice as hard as before ; at \u201cThree\u201d three times as hard and at \u201c Four\u201d four times as hard.","page":105},{"file":"p0106.txt","language":"en","ocr_en":"io6\nE. IF. Scripture,\nWhen this has been done a number of times in order to familiarize the subject with the experiment, the experimenter gives the drum a slight turn before each pressure so that the records are separated distinctly. Five sets of four marks each are thus obtained.\nThe dynamometer is placed in a screw vise so that the cheeks of the vise take the places of the fingers of the subject. The drum is turned so that the quill point is at the first record. The vise is screwed up till the point has moved as far as the original record ; the number of kilograms corresponding to this movement is read off from the scale. The tenths of a kilogram are estimated by the eye. The result is recorded in the first column of the record blank. The drum is now turned till the point is opposite the second record : the vise is screwed up and its value determined as before. The result is placed in the second column. In the same manner all the records are determined, the results being placed in the columns i, 2, 3, 4 according to the original intention of the subject in exerting the pressures.\nIn each set of records the pressures were intended to stand in the relation of i, 2, 3 and 4; the actual relations are found by dividing each record of a set by the record for the first pressure in that set. Thus the records 1.1, 1.8, 2.4, 3.2 stand in the relations of 1.0, 1.6, 2.2, 2.9. This is done separately for each set. The results for each pressure are averaged. The following is a specimen record.\nMental .scale of pressure\tI\tII\tIII\tIV\nActual pressure exerted\tI.I\t1.8\t2.4\t3-2\n\t1.8\t2.1\t2.8\t3-7\n\tI-3\t1.9\t2-5\t3-3\n\t1.0\t1.8\t2.4\t3-i\n\ti-3\ti-7\t2-5\t3-5\nRelative pressure exerted\t1.0\t1.6\t2.2\t2.9\n\t1.0\t1.2\t1.6\t2.1\n\t1.0\t1-5\t1-7\t2*5\n\tI 0\t1.8\t2.4\t3-1\n\t1.0\ti-3\t1.9\t2-7\nAverage\t1.0\t*\u25a05\t2.0\t2-7\nThe experiments are repeated, beginning\t\twith a\tvery strong pressure\t\nand proceeding in the the order\t\u201cFour,\u201d \u201c\tThree,\u2019\t\u2019 \u201cTwo,\u2019\t\u2019 \u201cOne.\u201d\nB. Curve of fatigue. The preparations are made as before. At the word \u201cGo\u201d the subject presses on the dynamometer as strongly as possible and maintains the pressure at its maximum until told to stop. The experimenter keeps the drum turning slowly for 10 sec. by the watch ; thereupon he calls \u201cStop.\u201d The' line traced upon the drum shows the","page":106},{"file":"p0107.txt","language":"en","ocr_en":"Elementary course in psychological measurements.\t107\nfluctuation in the maximum amount of effort. The fatigue curve is found by drawing a horizontal line from the highest point at the beginning of the record and then turning the record bottom up ; the curve then runs, of course, from right to left. The amount of fatigue is to be found by taking readings at the beginning and at the end of the curve in the manner described under A.\nC.\tDiversion of energy. The preparations are made as before, but instead of closing the eyes the subject keeps them fixed on a printed page. At the word \u201cGo\u201d he is to press as hard as possible; this maximum pressure is to be kept up without any relaxation till the end of the experiment. Shortly after starting the experimenter calls \u201c Read \u201d and at the same time makes a check on the drum near the quill point by means of a small stick or a pencil. The subject begins reading aloud at the signal and, without relaxing the pressure, continues to read until the words \u201cStop reading.\u201d1\nD.\tPreserving the record. The drum is placed horizontally, the paper is slit across, one end is caught by a clamp, the sheet is run through a solution of shellac and is hung up to dry.\nThis shellac solution is contained in a large bottle at the varnishing stand. Lift the bottle from the lower shelf and place it on the upper one. The varnish runs through the rubber tube and floods the varnishing tray. The shellac solution is composed of 1 part by volume of saturated solution of shellac in alcohol and 4 parts of 95% alcohol. In running the sheet through the solution get the fore edge of the sheet under the solution first and keep the smoked side upward. After the sheet has been varnished, the bottle must be replaced on the lower shelf ; the varnish runs back into it and is kept from evaporation.\nPoints to be noted.\ni. Possibility of establishing mental scales. 2. The falling off in the effort in what is meant by \u201cfatigue\u201d in this case. To call it \u201cthe effect of fatigue\u201d would bring in assumptions not justified by the experiment ; a scientific definition must start with the facts as immediately given.\nQuestions.\ni. How was the standard physical scale established ?\t2. What general\nconclusions would you draw concerning mental energy? 3. How many adjustments can you point out on the piston-recorder?\n1 Such a record is shown in I'ig. 48 of The New Psychology.","page":107},{"file":"p0108.txt","language":"en","ocr_en":"io8\tE. IV. Scripture,\nExercise VIII.\u2014Rhythmic movements.\n(Needed : Jacquet graphic chronometer, kymograph, Marey tambours, upright wooden scale, paper, smoking and varnishing arrangements, 2 standards. )\nApparatus.\na.\tGraphic chronometer. This is essentially a fine stop watch with a recording point and electric contact. The smaller dial indicates seconds, the larger one minutes. The chronometer is wound by the screw at the back ; it will run for 4'* without error due to laxity of spring, or 6h with a small error. The catch b at the bottom, when moved to the right, starts the chronometer ; when to the left, stops it. Pressure on the catch a at the side returns the hands to o. The recording point d makes a movement once a second, or five times a second, according as the catch c at the back is pushed in or pulled out. The extent of the movement of the recording point is regulated by the screw c beneath it. When the chronometer is placed vertically the weight of the recording lever is sufficient to bring it back when moved, but when it is in a horizontal position the screw / at the right-hand side should be made to bear lightly on the spring at the opposite end of the lever. The chronometer is held on the support by the screw /. When used with the drum, it is brought near the surface at a tangent by moving the support ; the finer adjustment is then made by turning the screw m in front.\nb.\tKymograph. This is a recording drum moved by clockwork. It differs from the hand-drum by having its speed so carefully regulated that, when its rate of revolution is once determined, it can be depended upon to maintain that rate with a high degree of accuracy, provided the spring is kept wound up to about the same tension and the whole apparatus is in perfect order. The lettering used in the following instructions will be found painted on the apparatus at the appropriate points.\nFirst place the drum in the separate horizontal support as in Fix. VII. Place some paste on one end of the sheet of glazed drum-paper. Stretch the paper around the drum tightly and bring the pasted end over the other end. Coat the paper with smoke by holding a gas flame close beneath it.\nLift the drum from the support, grasping it around the ring O at the end. Raise the spring G of the kymograph by the arm F till it catches. Let the end of the drum-axle drop into the socket F. Bring the groove of the ring O up till it catches on the wheel at the end of the arm N. Bring the top of the axle just below the socket held by G, and let F snap. The drum is now in position ; it should be turned till the projecting point at the bottom of the axle catches in a notch of the spring F. If the kymograph is not firm upon the table, adjust the leg M.","page":108},{"file":"p0109.txt","language":"en","ocr_en":"Elementary course in psychological measurements.\n109\n\n\\ >;\nhi\u00a3r\n0 > -U \u00ab\n\u25a0a\n\u202291 oi.i","page":109},{"file":"p0110.txt","language":"en","ocr_en":"I IO\nE. IV. Scripture,\nWind up the clock-spring by the handle A. Move the brake E in order to release the governor D. When the screw B is tight the drum will turn with the clockwork ; when it is loose, the drum is disconnected. The connection of the clockwork with the drum axle is established by the large friction disc which presses against the small friction roll X. When handling the drum, always disconnect it by turning B; this keeps the friction disc from being ground by chance movements of the roll X.\nThe speed of the friction disc is changed by different combinations of the gears of the clockwork. The case of the clockwork can be opened by turning two projecting screws at the side. There are two gears that move sidewise on their axles, a lower one (white stripe), and an upper one (red stripe). The following table gives the speeds approximately obtainable by the different combinations.\nSPEED\tPOSITION OF NAMK. LOWER W11 EEL.\tPOSITION OF UPPER WHEEL.\tFRICTION ROLL AT LOWEST POINT.\tFRICTION ROLL AT INCHEST POINT.\nI\tLeft.\tRight (weak spring).\tih 30\u2122\t12m\nII\tLeft.\tLeft (medium spring).\t6m\t45s\nIll ! Left.\tMiddle (strong spring).\t2\u00bbi\t15\"\nIV\tRight.\tRight (weak spring).\t12\u201c\tiyim\nY\tRight.\tLeft (medium spring).\t40\"\t5'\nVI\tRight.\tMiddle (strong spring).\t16s\t2*\nThere are three sets of springs for the governor; that set should be chosen which allows the wings of the governor to take a middle position when in motion. When the upper wheel is in the middle position the screw C should be turned so as to bring the little wheel at the end of the arm into position between the largest and smallest cog-wheels.\nThe intermediate speeds between the figures in the table are obtained by moving the roll X by means of the screw B. An index connected with X moves over a scale so that a speed once found can be reproduced by direct adjustment of the index to the same point ; to avoid back-lash the adjustment should be made in the direction from zero upward. Adjust the kymograph for this exercise to about 20s for 1 revolution.\nc. Tambours. The essential principle of the tambour is found in its construction as a metallic air-chamber with a rubber top and a side tube. There are two tambours, the receiver and the recorder.\nAny desired movement may be communicated to the straight lever (1) of the receiver (2). This lever communicates the movement to the air inside by its varying pressure on the rubber top. The movement of the air is communicated along the rubber tube (3) to the'recorder (5). The","page":110},{"file":"p0111.txt","language":"en","ocr_en":"Elementary course in psychological measurements.\n111\nrubber top of the recorder moves in response to the movements of the air, and the light curved lever (9) resting on it consequently repeats the movements of the straight lever of the receiver. The point of connection (8) to the recording lever can be moved so as to obtain different degrees of amplification ; the body of the tambour is kept centered beneath the point of connection by a screw (6) at the back. For the present exercise any convenient amplification is used. The position of the point on the drum is adjusted by the arm (7) which moves the fulcrum. The valve (4) is used as in Ex. VII.\nExperiments.\nA. Getting the time-line. The drum is set in motion. The graphic chronometer, adjusted to beat seconds, is placed on the upright support. The support is moved till the recording point nearly touches the smoked surface at a tangent. The point is brought into light contact by the adjusting screw. The chronometer thus traces a line with checks at intervals of i\". The chronometer is then carefully removed and placed in its box.\nR. Recording an instinctively chosen rhythm. The recording tambour is placed so that its point draws a line on the drum. The receiver is arranged with its lever in front of a vertical scale.\nThe subject takes the straight lever between thumb and finger at the point marked in black. He is to move it up and down as regularly as possible over a distance of about 3e1\". By \u201c regularly \u201d is meant evenly and at regular intervals. While this is being done, the experimenter allows the drum to make one revolution. By turning the handle //, the drum is then lowered sufficiently for another record.\nC. Recording an arbitrary rhythm. The subject tries to beat twice as fast as before.\nComputation.\nThe drum is lifted out of the apparatus by grasping it around the ring and raising the lever G. It is placed in the horizontal support. The experimenter writes on it with a pointed instrument the name of the subject, the date and the time. With the point of a knife the paper is slit across, the thumb being kept over the beginning of the slit in order to keep the paper from falling. The end of the paper is caught by a varnishing clamp. The paper is run through the varnishing solution of shellac and hung up to dry.1\n1 Observations connected with this experiment led me to report ( Science, 1896, n. s. IV 535), the following law, subject to amplification and correction by further experiment. The probable error (all apparatus errors being negligible) is a good measure of","page":111},{"file":"p0112.txt","language":"en","ocr_en":"I 12\nE. IV. Scripture,\nWhen the paper is dry the lower edge containing the time-record is cut off to serve as a scale of seconds. Ten of the distances from top to top of the waves in each rhythm are measured by this scale, giving the results in seconds and estimated tenths. The average and the character-variations are found in each case.\nSpecimen record.\nNatural rhythm.\tArbitrary rhythm.\nm\tV\tvi\tin\tV\tt/2\n1.8\t0.16\t0.0256\t1.1\t0.05\t0.0025\n1.8\t.16\t.0256\t0.9\t.15\t.0225\ni-7\t.06\t.0036\t1.0\t.05\t.0025\nI-5\t\u2022 14\t.0196\t1.2\t\u25a0 15\t.0225\n1.7\t.06\t.0036\t0.8\t\u2022 25\t.0625\ni-5\t.14\t.0196\t1.0\t.05\t.0025\n1.6\t.04\t.0016\tI.I\t.05\t.0025\n1.8\t.16\t.0256\t1.6\t\u202255\t.3025\n1.4\t\u202224\t.0576\t0.9\t\u202215\t.0225\n1.6\t.04\t.0016\t\u00b0-9\t\u202215\t.0225\n1.64\t9)0.1840\t\t1.05\t\t9)0.465\u00b0\n\t10\t)0.0204\t\t\t10)0.0519\n\t\t0.0020\t\t\tO.OO52\nj/0.0020 = 0.04\t\t\t\t1/0.0052\t= 0.07\nkx\u00b0\u00b04 = 0.03\t\t\t\t2AX 007\t= 0.05\na\t=I\u202264 \u00b1 0 03\t\t\ta \u2014 1.05\tzt 0.05\nPoints to be noted.\ni. The method of obtaining toths of a unit by the eye is in this case just as accurate as if a carefully prepared scale were used. 2. Although\nthe subject\u2019s irregularity (see above p. 21, note 1), or of the difficulty of his mental processes. Using it thus as a measure of the disadvantage of a rhythm we can express the relation of the disadvantage to the length as r=f(t) where r is the probable error and t the length of the time in the rhythmic movement. The law proposed is\nr\nI fzd'ri=constant>\nwhere r and t have the same meanings as before, T is the length of the time chosen naturally and 11\u2014T\\ indicates that the sign of the quantity is disregarded. In other words, the amount of irregularity is proportional to the deviation from the natural rhythm. The relation here observed is illustrated by the well-known fact that in such rhythmic movements as walking, running, etc., a certain frequency in the repetition of the movement is most favorable to the accomplishment of work. Thus, to go the greatest distance in steady traveling day by day, the horse or the bicyclist must move his limbs with a certain frequency: not too rapid, as this would fatigue and cut short the journey\u00bb and not too slow, as this also would be fatiguing and wasteful. This favorable frequency is a particular one for each individual and for each condition in which he is found ; any deviation diminishes the final result.","page":112},{"file":"p0113.txt","language":"en","ocr_en":"Elementary course in psychological measurements.\n1 *3\nthe records could easily he read in iooths, the degree of accuracy appropriate to the experiment lies in ioths.\nQuestions.\ni. What is the relation between the probable error and regularity? 2. How would you express this relation mathematically?\nExercise IX.\u2014Maximum rapidity oe repeated volitions.\n(Needed : recording drum, paper, smoking and varnishing arrangements, too v. d. electric fork, fork support, double contact key, spark coil, condenser, battery of I A, battery of 4A. )\nApparatus.\na.\tRecording drum. This drum' consists essentially of an evenly turned cylinder rotating on two centers. Parallel to the axis of the drum are two rails guiding an upright support, called the marker support. The support is moved by a screw operated by a handle at the end. Glazed drum-paper is stretched around the drum and smoked in the manner described in Ex. VII.\nb.\tElectric fork. An electric current of 1 amp\u00e8re is brought to the binding post at the back of the fork. It travels along the prong to the platinum wire. When this wire is in contact with the plantinum-covered disc the current passes to the base of the magnet, whence it goes through the wire of the magnet, out at the insulated post and back to the battery. While the current is passing, the coil becomes magnetic and pulls the prongs of the fork inward. If the platinum wire is in very light contact with the disc, this movement of the prongs will separate them, and the current will be interrupted. Consequently the coil ceases to be magnetic and the prongs fly outward. The outward movement, however, brings the platinum wire into contact with the disc again ; the current passes through the coil, and the movement begins as before. With a proper adjustment of the disc in relation to the platinum wire the fork will continue to vibrate as long as the current is supplied. The proper adjustment is attained by starting the disc away from the wire and screwing it up till it just touches\u2014which can be seen from the darkening of the little lamp of the battery\u2014and then giving about of a turn more. If the fork does not begin to vibrate of its own accord, it is\n1 Sec Fig. 33 in Stud. Vale Psych. Lab., 1893 I 100, and Fig. 6 in The New Psy-chology.\n8","page":113},{"file":"p0114.txt","language":"en","ocr_en":"E. It'. Scripture,\n114\nstarted by a light blow of the finger. A light recording point of fine spring steel is attached to one prong.1\nc. Fork supportr The object of the fork support is to provide a delicate and convenient adjustment of the contact point on the smoked paper. It is fastened to the marker support of the drum by the clamp AI, by which it can be raised, lowered or turned as desired. The rod R is placed in the hole through the base of the fork ; the screw S clamps the base firmly. The screw I gives adjustment on the rod P. The fork is first placed nearly in position with its steel recording point at a tangent to the drum and its plane of vibration parallel to the drum axis. It is now lowered by the screw N, acting on the arm O, till the point is in good contact with the paper.\nti. Double contact keyA This key consists of a lever moving on a bar hung between centers. A spring holds the front end of the key up ; the tension of this spring is adjusted by the screw Z. It should be great enough to hold the lever up as far as it will go, but small enough to offer the least possible resistance to movement. At F a platinum point is inserted. Just below Y there is another point X, which is supported by a ring of hard rubber so that there is no metallic connection with the frame. A wire leads from X to the binding-post 1. At the back of the lever there is a screw IV, carrying a platinum point V. Just below F there is another point Usupported by hard rubber and in connection with the post 2. The extent to which the lever moves is regulated by turning IV. There should be enough movement to be distinctly felt, but not enough to cause loss of time. The framework of the key (and consequently the contacts Y and V) is connected to post 3.\nBring the wires from the 4-amp\u00e8re battery to the posts 1 and 3 ; notice (by the darkening of the small lamp) that the current passes through the key whenever Y and X are kept in contact by pressure on the rubber knob A.\nBring the battery wires to 2 and 3. Notice that the current passes whenever V and U are in contact.\n1\tTo prepare these steel points I procure from the clock factory a fiat strip of fine \u201c pendulum wire. \u2019 \u2019 Pieces are cut off of 3 cm. length. A hole to fit over the screw is made in each piece ; the opposite end is cut to a sharp point and bent. Such a piece is substituted for the usual brass point that comes with the fork. The great elasticity of the steel reduces the friction to a minimum ; its hardness keeps the point sharp for a long time, whereby a very fine line may be produced.\n2\tSee above, p. 82.\na The lettering is found on the apparatus. A picture of such a key without the adjusting screws '/. and Y is given in The New Psychology, Pig. 27 ; post I is nearest, post 2 is farthest and post 3 between them.","page":114},{"file":"p0115.txt","language":"en","ocr_en":"Eicmcntary course in psychological measurements.\t115\nConnect 1 and 2 by a short wire. The current is then interrupted for an instant at each movement of the key downward or upward.\nc. Spark coil. The spark coil consists of two coils of wire.1 The inner one, \u201cprimary coil,\u201d is made of a few turns of coarse wire ending in the terminals P. The outer one, \u201csecondary coil,\u201d consists of many turns of very fine wire, ending in the terminals 5. Insert a metal rod F through one of the posts .S' and bring its point within about of the other post. Bring one wire of the 4A battery to one of the posts P. Touch the other post with the other wire for an instant ; notice that a spark jumps across at S.\nBring one wire of the 4A battery to one of the posts P and the other one to the post 2 of the telegraph key. Connect post 3 with the other post P by an extra wire. Notice that a spark is produced every time the key knob is pressed or released.\nRemove the rod A'and connect one of the posts S to the metallic back of the fork by a light wire and the other one to the binding post H of the drum by a similar wire. The wooden base of the fork interrupts metallic connection between the two wires and the spark is forced to fly off the recording point and through the paper to the drum. This makes a white dot on the paper. 2\nf. Condenser. The condenser consists of two sets of sheets of tin-foil arranged alternately. The sets are connected to the two posts K, L. The sheets are kept separate from each other by sheets of paper. Two wires are brought from K and L to the posts 2 and 3 of the key without disturbing the battery connections. Notice that the spark at the drum is made stronger by using the condenser.\nExperiments.\nA.\tAdjustments. The fork is adjusted at the farther end of the drum. The experimenter sets the drum in motion by striking the edge with his hand. By turning the handle that moves the fork support he pulls the fork along toward him. The speed of the drum should be such that a single wave extends over about icm. During the experiment the fork support should move fast enough to make the fork trace a spiral without overlapping, but slow enough not to waste paper. The subject adjusts the key evenly on the table. He then taps several times to prove that the spark connections are in order.\nB.\tRecording the most rapid tapping. The subject takes a comfortable\n1\tThe separable coil should Ire used, see above, p. 81.\n2\tThe plan of connection of the spark coil and fork is similar to that shown in Fig. 6 of the New Psychology.","page":115},{"file":"p0116.txt","language":"en","ocr_en":"Ji. ] V. Scripture,\n116\nposition, grasps the knob of the key between thumb and middle finger, and, steadying the key with the other hand, makes the lever vibrate as rapidly as possible. This is done by way of practice for a few moments without making a record.\nThe subject is ready. The experimenter calls \u201cNow,\u201d whereupon the subject begins to tap as rapidly as possible. The drum is set going and a record is taken for a few seconds. The name of the subject is written in the smoke by a pencil or a pointed stick.\nC.\tPreparing the record. The paper is slit crosswise with a knife, lifted at one end and run through a solution of shellac as described in Ex. VII.\nD.\tComputing the results. When the record is dry a portion about in the middle is selected for computation. As a dot was made at each tap and release of the key, the distance between two dots on the fork-line, or time-line, gives the time for a single movement. The time is divided into iooths by the wave of the fork-line ; the roooths are obtained by estimating the extra ioths of a wave by the eye. Ten successive records are counted. The average and the probable error arc found.\nSpecimen record.\nm\tV\tV1\n40\t0.7\t0.49\n39\ti-7\t2.89\n40\t0.7\t0.49\n42\ti-3\t1.69\n41\to-3\t0.09\n43\t2-3\t5.29\n40\t0.7\t0.49\n39\t1-7\t2.89\n41\t\u00b0-3\t0.09\n42\t*\u20223\t1.69\n40.7\t\t9)\t16.10 10)\t1.56 0.16\n1/0.16 = 0.4 ^X\u00b0'4 = \u00b0\u20193 o = 4\u00b0-7\u00b1\u00b0-3\nTheoretical considerations.\nThe repeated taps were produced by successive volitions resulting in the alternating movements, down and back. Assuming that the two movements represent two volitions alternated as rapidly as possible, the","page":116},{"file":"p0117.txt","language":"en","ocr_en":"Elementary course in psychological measurements.\n117\nresult gives the average time required as a minimum for the rise and execution of a volition.1\nPoints to be noted.\ni. Regularity and rapidity may be quite different in different persons. 2. A very rapid person may not be a very regular one.\nQuestions.\ni. How are we justified in considering the time between two muscular movements as a mental time? 2. What means would you suggest for shortening the tap-time and decreasing the probable error?\nExercise X.\u2014Simple reaction to sound.\n(Needed: recording drum, automatic break, smoking and varnishing arrangements, 100 v. d. electric fork, Pfeil marker, Df.prkz marker, telephone, reaction key, adjustable marker support, simple break switch, two batteries of 1 amp\u00e8re, one battery of 2 amp\u00e8res. )2\nApparatus.\na. Recording drum. The drum used in this exercise is known as the \u201cstandard drum \u201d on account of the steadiness of its movement, which is due to the weight of the wheel.3 Glazed drum paper of the proper size is adjusted around the drum and is smoked on that quarter which is beneath the projecting arm C. The drum is moved by a ratchet handle at the top ; it may be stopped by the brake at the side.\n\u25a0The following table gives the results on 20 students in 1896 :\nAverages for all.\nSubject :\tA\tB\tC\tE\tF\tG\tH\tI\tI\tJ\tL\tM\tX\tO\tP\tQ R\tS\tu z\t\nAverage :\t41\t71\t59\t46\t80\t123\t7*\t92\t77\tXI3\t97\t33\t84\t72\t52\t62 147\txx7\txx8 60\t81\nAverage 1 variation : j\ti 12\t24\t18\t8\t9\t50\t2\t28\t*3\t36\tXX\tx4\t40\txo\tx9\t5 20\tx7\t6 3\tx7\nRelative average\t\t33\t30\t*7\tXI\t4\u00bb\t2\t30\t17\t32\tXI\t42\t48\t7\t36\t7 12\tx5\t5 5\t21 per cent.\nvariation : J\t1\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\nProbable 1 error : J\t\u2022 3-4\t6.8\t5-x\t2.2\t2.5 14.0\t\t0.6 7.8\t\t3-6\txo.x\t3-x\t3-9\tix.2\t2.8\t5-3\tX.4 5-6\t7.8\t1.70.8\t4-5\nThe results give the times for the alternated movements naturally used by unpracticed persons in attempting to move the telegraph key. Ily trial the subject can finally select the most rapid movement, which will frequently be much quicker than the original one. The average variation (or mean variation) is the average of the residuals; in the example above it would be the average for the column v.\nsThe drum of the previous exercise, which is fitted with an automatic break, may be used for this exercise. The fork and adjustable marker support may likewise be the same as before. In such a case the previous exercise should be put far enough ahead of this one in the course to avoid any need for the same pieces in two simultaneous exercises. It is preferable to have several drums, all of which should have automatic contacts. 3See Stud. Yale Psych. Lab., 1895, III, Fig. 16.","page":117},{"file":"p0118.txt","language":"en","ocr_en":"F. IV. Scripture,\ni iS\nb.\tAutomatic break.' The projecting arm Cas it passes the rubber block D strikes a projecting pin G and moves it. On the other side of D there is the small arm I made into one piece with the pin G ; it, therefore, moves when G is struck. This movement brings a platinum (joint away from the platinum point of the screw If. Thus, if the two wires of an electric circuit are brought to the posts E and F, the current is interrupted every time C strikes G.\nc.\tMarker support. The carriage F riding on the steel post is movable by the handle J. It carries a projecting rod I, to which forks and markers may be attached. When two markers are used, as in the present exercise, an adjustable support1 2 M is placed on Z. The rod of M is placed vertically. This rod can be rotated by the screw N ox lever O.\nd.\tDcprcz marker. This marker is adjusted on the rod of the support by the screw P. It is so placed that when it is lengthened, by turning the screw Q, the fine point at the end can be brought into delicate contact with the smoked surface. Bring the two wires from a iA battery to the posts P, S. Notice that whenever the circuit is completed the armature V is drawn to the magnet U, and that when it is broken the armature flies back. If this does not happen, the adjustment is to be made more delicate by altering the tension of the armature spring at the back or by changing the amplitude of vibration of the armature by moving the cone by means of the screw T.\ne.\tElectric fork. The fork used in this exercise is arranged to vibrate just as that in Ex. IX. The wires from a battery in iA are brought to the two binding-posts as before. The fork is not attached to the drum, but is placed on the table.\nf.\tPfeil marker. The Pfeii. marker is placed on the adjustable support by means of its clamp in such a way that its point is downward and close to the other marker. The battery wire is removed from one post of the fork and is placed in one of the posts of the marker. A wire is then run from the other post to the fork. Whenever the current passes, the coils of the marker become magnetic and attract the armature D ; when the current is interrupted, the armature is released. As the current is made and broken ioo times per second by the fork, the armature vibrates ioo times per second. The vibration is transmitted to the recording point by a connecting bar. The extent of the vibration is regulated by a screw F, which adjusts the distance of the magnets from the armature. The finer adjustment of the point against the drum is accom-\n1\tThe lettering is on the apparatus; the principle of the automatic break is similar to that shown in l\u00fcg. 17.\n2\tSee above, l\u00fcg. 10 ; for this exercise the clamp .1/ is made of hard rubber.","page":118},{"file":"p0119.txt","language":"en","ocr_en":"Elementary course in psychological measurements.\t119\nplished by a screw G at the back. The marker is first adjusted so that its ]>oint is just above the point of the Df.prez marker, and then the exact amount of pressure against the drum is attained by G. As the drum is turned, a time line is drawn whose waves each indicate 1/100 of a second.\nExperiments.\nA.\tFinding the latent time of the Dcprez marker. The current is brought to one post of the automatic break, then from the other post to the Df.prez marker and from the marker back to the battery. The drum is slowly rotated till the arm C opens the break and makes a check with the marker. If this is carefully done, the check marks the exact spot at which the break occurs. The carriage is then run down and back in order to draw the zero line, or the line at which the break occurs.\nWith the Pfeil marker in vibration the drum is now set in rapid rotation. The carriage is then moved downward with sufficient rapidity to keep the records separate. The result is a series of records, each consisting of a time-line and the line drawn by the Df.prez marker. The paper is removed and varnished. The distance from the zero-line to the check in the marker-line gives, in terms of space, the latent time of the marker at the break ; this distance is turned into time by comparison with the time-line. The time is read in \u00eeoooths of a second. Five records are computed to find the average and the probable error.\nB.\tAdjusting the reaction experiment. A new piece of paper is placed on the drum and smoked all around. The Pfeil marker is adjusted as before. The zero-line is made as before.\nThe iA circuit through the automatic break is taken from the marker and run through a telephone instead ; a click is thus produced in the telephone whenever the arm C strikes the point G. A switch for turning off the current is inserted in the circuit.\nAnother iA current is run through the Df.prez marker and then through the reaction key. This key comprises two steel rods on which run two rubber slides.1 The adjustable slide A is fastened at any desired place by the nut B ; the excursion of the movable slide M can thus be regulated. For the present experiment the excursion should be about 3 The index finger is placed in the hole of M, the thumb is placed in the hole of A and the key is steadied by the third finger. The battery wires are brought to the post of Mand the post T at the top. When the finger is extended, the circuit is closed ; as soon as it is moved, the circuit is broken and the Deprez marker moves.\n1 See Stud. Yale Psych. I.ah., 1893 I, Fig. 30. The lettering is on the apparatus.","page":119},{"file":"p0120.txt","language":"en","ocr_en":"120\nF. IV. Scripture,\nThe subject is comfortably seated with the reaction key in his hand ; he must be so placed that he sees nothing of the experimenter\u2019s movements.\nC.\tPerforming the experiment. The subject is called to attention by telephone clicks produced by tapping the automatic break. The switch is then opened.\nThe drum is set in rotation ; the switch is closed during one revolution, while the carriage is lowered. The telephone click is heard by the subject and the reaction is recorded by the marker. After a few turns of the drum the switch is again closed, while the carriage is lowered as before. As many records as possible are obtained on the drum. The paper is removed and varnished.\nD.\tComputing the results. The average and the probable error are found for the reaction experiments. Since the latent time of the marker is included in the recorded time, its amount must be subtracted in order to find the reaction-time.\nSpecimen record.1\nMarker.\t\t\tReaction.\nm\tv\tm\tV\t\n2\tO\t174\t24-7\t610.09\n2\tO\t124\t25-3\t640.09\n2\tO\t156\t6.7\t44.89\n2\tO\t130\t19-3\t372.49\n2\tO\t166\t16.7\t278.89\n2\tO\ti4i\t8-3\t68.89\n\t154\t4-7\t22.09\n\t7)1045\t\t6)2037.53\n\t149-3\t\tio)339-59\n\t\t\t33 96\n\t\tV33-96 =\t= 5.8\n\t\tYsX 5-8 =\t= 3-9\nLatent time of marker, a =\t2<r, r = \u00bb ; Reaction-time, a\t\t= 149<r \u2014 2<r=I47<r, ;\n1 Results for 12 students i\tin 1896 are given\tin the following table :\t\nMarker.\t\tSubject.\t\nLatent\tAverage\tReaction' Average\t\ntime.\tvariation.\ttime.\tvariation.\nA i\t0\tIl6\t6\n\u00df i\t0\t146\tl6\nD o\t0\t168\t24\nA 3\t0\t125\t15\nA 3\t0\tM3\t12\nO 3\t0\t170\t27\nAt o\t0\t167\t14\nN o\t0\t152\t14\nO i\t0\t164\t31\nP i\t0\t122\t18\nQ 2\t0\ti\u00b07\t20\nA* 2\t0\tIOO\t6l\nAverage :\t2\t0\t137\t21\nThe different latent times for the marker are due to different adjustments of the\t\t\t","page":120},{"file":"p0121.txt","language":"en","ocr_en":"I 2 I\nElementary eourse m psychological measurements.\nPoints to he noted.\ni. The determination of the reaction-time of the subject was closely analogous to that of the latent time of the marker; it would be quite justifiable to speak of the \u201c reaction-time of the marker \u201d or the \u201c latent time of the subject.\u201d 2. Since the probable error of the marker was o, the probable error for the reaction records must be a personal quantity of the subject.\nQuestions.\ni. How would you proceed to determine the latent time for a spark coil? 2. What mental element that was measured in Ex. IX is present in the subject\u2019s reaction ?\nExercise XI.\u2014Regulated rhythmic action..\n(Needed: recording drum, motor, 100 v. d. fork, fork support, automatic make, sounder, break key, spark coil, condenser, smoking and varnishing arrangements, batteries of I A, 2 and 3A, and 4A. )\nApparatus.\nThe automatic contact (Fig. 17) is attached to one of the posts of the drum by the screw E through the rubber block V. A projecting pin in the drum strikes the spring arm B and depresses it slightly for an instant.\nThe current is brought to the post A and passes through the arm B to the platinum disc at G. Every time the pin on the drum strikes B contact is made by G against /and the circuit is closed. E is a screw with a rubber point against which B may rest. The automatic make may be turned into an automatic break by interchanging / and E.\nTo adjust the position of the automatic contact apparatus the screw E","page":121},{"file":"p0122.txt","language":"en","ocr_en":"122\tE. II\u2019. Scripture,\nis loosened : it is also so arranged that it can he swung entirely out of the way when not needed.\nThe remaining apparatus is the same as that used in Ex. VI.\nThe 2A current is sent through the automatic make and the sounder1 in series.\nThe fork is arranged to write on the drum and to be kept vibrating as in Ex. VI.\nThe 4A current is sent through the break current of the key in the way explained in Ex. VI.\nThe motor is arranged to run the drum by a belt connecting the two pulleys. The exact rate of speed described is obtained by varying the amount of current sent through the motor.\nExperiments.\nA.\tThe current through the motor is adjusted so that the drum revolves once a second. This is tested by comparing the clicks during a number of seconds with the indicated seconds of a watch. Then the subject, seated near the sounder and away from the drum, taps on the key knob in time with the clicks. A record is taken during about 15'.\nB.\tThe drum is adjusted to revolve twice a second, and another record is made.\nC.\tThe drum is adjusted to revolve three times a second, and a record is made.\nWith a full-width paper on the drum all the experiments can be obtained on one sheet.\nD.\tThe zero-line is found as in Ex. VII.\nE.\tVarnish and dry the paper.\nF.\tRead ten successive results to the 1/1000 sec. in each record ; distances to the left of the zero-line are \u2014, to the right +.\nG.\tCompute the constant errors (the latent time of the sounder is subtracted) and the probable errors (see Ex. III).\n1 the sounder has an electric contact arranged to close a circuit at the moment it strikes (a telegraph relay may be used). Its latent time for a current of 2 amp\u00e8res can be determined and marked on it. A convenient way of determining the latent time is to connect the contact of the sounder with the wires from C of the battery in Fig. 7, while the wires from G are connected to the primary poles of the spark coil. The condenser is also attached to the primary poles. As the contact points of the sounder strike, the current which passes through At, G and the coil, is short circuited; this is practically equivalent to its being interrupted ; a spark record is therefore made as usual.","page":122},{"file":"p0123.txt","language":"en","ocr_en":"Elementary course in psychological measurements.\t123\nSpecimen record.1\n\tSpeed\t/.\tSpeed 2.\t\t\t\tSpeed j\t\nIll\tv\tV1\tIll\tV\t\tm\tV\tr2\n+ 51\t6.0\t36.00\t-f- IO\t7.6\t57 76\t\u2014 5\t3-3\t10.89\n+ 39\t6.0\t36.\t\u2014 7\t9-4\t88.36\t\u2014 2\to-3\tO.O9\n+ 40\t5-o\t25-\t+ 6\t3-6\t12.96\t\u2014 3\ti-3\t1.69\n+ 47\t2.0\t4-\t+ 15\t12.6\t158.76\t+ 1\t2.7\t7.29\n+ 41\t4.0\tl6.\t\u2014 12\t14.4\t207.36\t\u2014 3\ti-3\t1.69\n+ 53\t8.0\t64.\t4\" 3\t0.6\t0.36\t\u20144\t2-3\t5-29\n+ 5\u00b0\t50\t25-\t\u2014 i\t3-4\t11.56\t\u2014 5\t3-3\t10.89\n+ 41\t4.0\tl6.\t\u2014 7\t9-4\t88.36\t+ 1\t2.7\t7.29\n+ 44\t1.0\tI.\t+ 8\t5.6\t3136\t4- 2\t3-7\ti3-69\n+ 44\t1.0\tI.\t+ 9\t6.6\t43-56\t\u2014 i\t0.7\t0.40\n+45-0\t\t9)224.00\t+ Si\t\t9)700.40\t+4\t\t9)59-3\u00b0\n\t\t10)25.00\t\u2014 27\t\t10)77.82\t\u201423\t\t10)6.59\n\t\t2.50\t+ 2.4\t\t7.78\t\u2014 1-7\t\t0.66\n\t1/2.50\t= 1.6\t\t1/7/78 =\t= 2.8\tl/ 0.66 =\t\t0.8\n\t?iY, i\t,6=1.1\t\t% X 2.8= 1.9\t\t2+\tII 00 d X\t=0.5\n\t\" = +\t38.0 \u00b1 11\ta = \u2014 46 zb i-9\t\t\ta -\t=-87\t\u00b1\u00b0-5\nPoints to be noted.\ni. There is a continual estimate of the time interval and an anticipatory reaction ; this estimate is corrected every time by occurrence of the sound. 2. The signs of + or \u2014 for the constant errors and the largeness or smallness of the probable errors are quite different for different subjects.2\t3. One of the speeds is specially favorable to regularity.\n1 The following table gives the results for 13 students in 1896 :\nSpeed i.\tSpeed 2.\tSpeed j.\nConstant Average Probable Constant Average Prob. Constant Average Prob.\n\terror.\t\tvariation.\terror.\terror.\tvariation.\terror.\terror.\tvariation.\terror.\nA\t4-\t51\t25\t7.0\t\u2014 28\t9\t2-5\t+ 20\t19\t5-3\nIt\t+\t44\t75\t21.0\t-84\t32\t9.0\t\u2014 9\t20\t5.6\nC\t\u2014\t53\t22\t6.2\t\u2014 23\u2014\t19\t5-3\t+ 75\t17\t4.8\nD\t+\t14\t57\t16.0\t\u2014 42\t*5\t4.2\t+ 2\tiS\t5-o\nK\t\u2014\t31\t19\t5-3\t\u2014 3\u00b0\t17\t4-8\t\u201410\t7\t2.0\nJ-\t\u2014\t57\t32\t9.0\t\u2014 20\t10\t2.8\t\u2014 25\t10\t2.8\n/\t\u2014\t57\t25\t7.0\t+ 36\t33\t9.2\t\u2014 33\t\u00ab9\t5-3\n/\t\u2014\u25a0\ti\u00b05\t37\t10.4\t\u2014 57\t13\t3-6\t\u2014 86\t20\t5-6\n0\t+\t12\t60\t16.8\t+ 1\u00b0\t19\t5-3\t+ 37\t3\u00b0\t8.4\nQ\t+\t29\t19\t5-3\t+ 1\u00b0\t7\t2.0\t+ 25\t7\t2.0\nA\u2019\t+\t15\t20\t5-6\t\u2014 8\tii\t3-1\t+ 14\t6\t1-7\nS\t\u2014\t28\t114\t3*-9\t\u2014 86\t16\t4-5\t\u2014 5\t7\t2.0\nT\t+\t72\t41\til.5\t-89\t83\t23.2\t\u2014 40\t5\tI 4\n1 See New Psychology, 182.","page":123},{"file":"p0124.txt","language":"en","ocr_en":"124\nE. IF. Scripture,\nQuestions.\ni. How should these experiments have been performed in order -to eliminate practice and fatigue? (See Ex. Ill, etc.)\t2. A comparison\nof the results with each other and with those of other individuals would be likely to give some information of a person\u2019s mental constitution in regard to promptness and reliability of response ; what conclusions do you draw from your record ?\nExercise XII.\u2014Simple and complex reaction-time.\n(Needed : recording drum, 100 v. d. fork, fork support, multiple key, 2 condensers, reaction key, telephone, resistance box, switch, telegraph key, sounder, 3 batteries of lA. one battery of 4A. )\nApparatus.\na.\tRecording drum, spark coil, condenser, fork, fork support, reaction key. See Exercises IX, X and XI.\nb.\tMultiple key.' This is a key having two levers, the upper one supported on a rod with center-bearings and the lower one on the rod as an axle. They are carefully adjusted so that both rotate around the same axial line. The upper lever is held down at the back by an adjustable spring ; the position and the extent of its movement are regulated by two adjusting screws that strike short upright rods. In front of the axis there are two contact screws on the upper lever. Opposite to them there are two platinum points on the lower lever. Either one of the upper screws can be made to strike the opposite point on the lower lever. If a circuit is brought to a contact screw and its opposite point, it will be closed whenever the upper lever is pressed downward. The current from a iA battery is brought to the two binding-posts connected with such a pair of contacts, and the closing of the circuit is observed.\nAt the back of the lower lever there are two contact screws opposite the contact points in the base. The rearmost of these screws is turned somewhat more than the other one ; it will then rest on its contact point owing to the pressure of a spring in front. The 4A current is sent through the contact. Whenever the knob of the key is pressed so that the front contact is made, the rear contact is broken. Thus the 4A circuit is broken at the moment the iA circuit is made.\nThe spark coil is placed in the 4A circuit and the condenser is arranged around the break, as in Ex. IX. Observe that each pressure on the knob makes a spark on the drum.\n1 See above p. 81.","page":124},{"file":"p0125.txt","language":"en","ocr_en":"Elementary course in psychological measurements.\n125\nInsert the telephone in the iA circuit. Observe that a spark is made whenever the telephone clicks.\nInsert the reaction key with a condenser in the 4A circuit. Observe that a spark is made whenever the reaction occurs.\nObserve that after the 4A circuit is broken by the multiple key no spark is made by the reaction key. This circuit must, therefore, be closed again after the break by the multiple key. At the front of the lower lever there is an adjustable contact point which dips into a cup of mercury covered by water. Connect the framework of the key to one of the posts for the back contact and the mercury cup to the other one. Adjust the contact point so that it is just above the surface of the mercury. Observe that as the key is depressed the 4A circuit is broken and then immediately closed again, so that it is ready for a break by the reaction key.\nThere are thus two sparks made ; one at the moment of the telephone click and another at the moment of reaction. By laying wires from the secondary poles of the coil to the fork and the drum, as in Ex. IX, a record of the time between these two sparks is obtained.\nc.\tTelephone, resistance and switch. The telephone has already been inserted in the iA circuit ; a shunt switch is now inserted in the same circuit. The wires are brought to the two binding posts ; when the switch is closed the current can pass through the telephone, but when it is open the current cannot pass. A resistance box (or a length of resistance wire) is connected around the switch, i. e., its two poles are connected to the two posts of the switch. When the switch is now opened, the current can pass by way of the resistance, which is adjusted so that the sound from the telephone is weakened. When the switch is closed the current can pass in practically full strength through the telephone and produce a loud sound.\nd.\tSounder and key. An independent circuit is made to pass through a telephone sounder and a telegraph key ; a pressure on the key produces a click of the sounder.\ne.\tArrangement. The multiple key is placed beside the drum so that the right hand can manipulate it readily while the left hand turns the handle of the marker-support on the drum. The telegraph key is placed beside the multiple key. The switch is placed just beyond.\nLong wires are now inserted in the recording circuit (multiple key and reaction key), in the stimulus circuit (multiple key and telephone) and in the warning circuit (telegraph key and sounder) so that the reaction key, telephone and sounder may be taken to a distant part of the room (or another room).","page":125},{"file":"p0126.txt","language":"en","ocr_en":"I2\u00d6\nE. JP. Scripture,\nExperiments.\nA.\tReaction with continuous expectation. The experimenter sets the drum in rotation and then taps a few times on the telegraph key. The switch is left closed. The subject holds the telephone to the ear and takes the reaction key in the hand as in Ex. X. He is to be constantly attentive and to react whenever the telephone clicks. The experimenter begins to move the marker carriage slowly and continues to do so while he presses the multiple key. Two sparks will be seen, one from the multiple key and one from the reaction key ; the multiple key is then released and the movement of the carriage stopped. The experiment is repeated for about 10 times at intervals of about 15s.\nB.\tReaction with specialized expectation. The experimenter proceeds as before, except by giving a warning signal on each occasion about 2^\u2019before the stimulus is produced. This he doos by tapping the telegraph key before pressing the multiple key. The subject is not to expect the telephone sound except when warned by the sounder. Ten experiments, as before.\nC.\tReaction with discrimination and choice. The subject is to react to the weaker sound and not to the louder one. The experimenter produces them in irregular order by manipulating the switch before each experiment. The procedure is as in C. Ten experiments.\nComputation.\nThe record sheet is removed from the drum and varnished as in Ex. VII. The latent time of the sounder (known from Ex. XI) is allowed for as each recorded is counted. The averages and probable errors are calculated. Denote the averages by a, b and c, and the probable errors by ra, rh and rc. Find p = b \u2014 a, q \u2014 c \u2014 b, s \u2014 rh \u2014 ro, and t = re \u2014 rb. The quantity p gives the lengthening ( + ) or shortening (\u2014) in the reaction-time due to the specializing of expectation ; gives the increase (-f ) or decrease ( \u2014) in irregularity for the same cause ; q gives the lengthening due to the introduction of additional mental processes ; and / gives the increase in irregularity for the same cause.\nPoints to be noted.\ni. To eliminate progressive and other errors the phenomena A, B and C should be investigated in pairs ; thus on one occasion A and B should be investigated, and B and C on another. 2. More mental labor is required of the subject in A.","page":126},{"file":"p0127.txt","language":"en","ocr_en":"Elementary course in psychological measurements.\n127\nQuestions.\ni. In determining the difference between A and B, how would you proceed in order to avoid progressive errors? 2. In determining the difference between B and C, on what system would you arrange the experiments in order to equalize differences that might arise from employing two intensities of sound?\nExercise XIII.\u2014Time estimates.\n(Needed : kymograph, contact attachment, 2 Mkumann contacts, 250 v. d. fork, fork box, 10 v. d. fork, Marey recording tambour, induction coil, telephone, key, spark coil, condenser, plain recording point, iA battery, 4A battery, smoking and varnishing arrangements, cross-section paper. )\nApparatus.\na. Kymograph. As in Ex. VIII.\nh. Contact attachment.' The support is screwed to the base of the kymogragh. The projecting gear wheel is adjusted to fit to the gear wheel that has been placed on the axle of the kymograph. As the kymograph moves, the arm on the contact attachment passes ov er the graduated circle.\nc. Meumann contact.- A metallic star with six arms is held to a rubber block by a screw in the center. At each rotation of the projecting arm it strikes an arm of the star and rotates it by of a revolution. Three of the arms bear small screws which touch two metallic points sunk in the rubber block. The rubber block is fixed to the circle of the contact attachment by the projecting screw.\nLet the circuit from the iA battery be sent through the back binding-post and the left-hand side post of a contact. The circuit is completed every time an arm bearing a screw passes over the sunken contact, and is broken every time the screw arm is moved off. Consequently the central arm alternately closes and opens the circuit as it passes this block. If a current producing a tone were sent through this contact, the tone would alternately be turned on and off. A red mark on the block opposite the graduated circle serves to indicate when the circuit is closed.\nThe second contact is connected in series with the first one. The two side posts of this contact are connected together; the circuit is broken when the arm of the star moves, but is immediately closed again by a\n'Fig. 236 in Wundt, Physiol. Psychol., II 424, Leipzig, 1893.\n11'ig. 5 in Mf.umann, Beitr\u00e4ge zur Psychologie des Zeitbewusstseins, Philos. Slud., 1896 XII 147.","page":127},{"file":"p0128.txt","language":"en","ocr_en":"128\nF. U . Scripture,\ncontact point reaching the second sunken contact. A white mark on the block indicates when the circuit is broken.\nConsequently : i. the current passes through the second block only when it passes through the first one, i. e., at alternate revolutions of the central arm ; 2. the current, when passing, is broken for a brief instant at the second block.\nd.\t250 v. d. fork. Same as 100 v. d. fork of Ex. IX, except in the rate of vibration, which is 250 times a second.\ne.\tFork box. This is a box padded with felt. Wires from the inside are brought to binding posts on the outside. The fork is put in the box and connected to the wires.\nf.\t10 v. d. fork. This fork, vibrating 10 times a second, is hung from a strong support. One prong carries a sliding collar connected by a small link to the metal disc on the top of a tambour. As the fork vibrates, the movement is mechanically transmitted to the air of the tambour. The amplitude of the movement of the top of the tambour is regulated by moving the collar along the prong. The tension of the rubber top is adjusted by means of the jamb nuts that clamp the tambour to the support.\ng.\tMarty recording tambour. As in Ex. VIII.\nI'm. iS.\nk. Induction coil. This consists of a short primary circuit of coarse wire (red) and a longer coil of thinner wire (green). The two coils are not connected ; the secondary one is loose and can be placed anywhere.\ni.\tKey. The key of Ex. IX is used ; only the rear (or break) contact is employed. The condenser is connected to the key around the break.\nj.\tSpark coil. As in Ex. IX.\nk.\tPlain recording point. A brass arm terminated by a flexible steel point of pendulum wire is attached to a small rubber block by a thumb screw (Fig. 18). The opening through which the screw passes is elongated to allow adjustment of the point lengthwise. During the experiment the point is adjusted to lightly touch the surface of the drum.","page":128},{"file":"p0129.txt","language":"en","ocr_en":"Elementary course in psychological measurements.\n129\nl.\tSmoking and varnishing. As in Ex. VII.\nm.\tTuning the drum. The Marey tambour is adjusted so as to write on the drum. The tube is connected with the tambour of the 10 v. d. fork. A blow is struck on one prong of the fork and the tambour-point vibrates 10 times a second. As the drum revolves, the time line is drawn on it. Adjust the drum to revolve once in 9 seconds. 1\nit. Adjustment of the tone. Bring one of the wires from the 1A battery to the fork by way of the fork box und from the fork through the primary circuit of the induction coil back to the battery. Connect the ends of the secondary coil to the telephone and lay the coil beside the primary one. A tone is heard in the telephone when the fork is set vibrating.\nBreak into the telephone circuit and by extra wires insert the star contacts (which have already been connected together as described under c). When the kymograph is running, a tone will be turned on and then interrupted for an instant ; this occurs at alternate revolutions.\no.\tAdjusting the spark record. The current from the 4A battery is run through the break key and through the primary circuit of the spark coil. The condenser must be connected around the break. The simple recording point is connected to one of the secondary poles, the drum to the other. Whenever the key is tapped, a spark flies from the point to the drum.\np.\tDrawing the zero-lines. Place the first contact with its red mark at o\u00b0. Loosen the back screw B (see Fig. 17) of the kymograph. Turn the drum slowly till the tone is first heard. Draw a zero-line by lowering the drum axially by the handle H. This line indicates the moment at which the tone begins. With the second contact at 40\u00b0 turn the drum further until the tone has been interrupted and just begun again ; draw another zero-line, which indicates the moment at which the second tone begins. Place the second contact at 8o\u00b0 and then at 120\u00b0 and draw zero-lines as before.\nExperiments.\nA. Measuring the time estimate for a tone of one second. Place the contacts so that the red and white indicating points are 40\u00b0 apart. This will give a tone lasting one second, then a moment\u2019s interruption ( of a sec.) and thereafter another tone.\nThe subject is seated with eyes closed. The kymograph is set in motion. The tone begins, is interrupted for an instant and is begun again. When the subject thinks that it has lasted as long after the\n1 If desired, the drum may be timed by a watch, by the method used in Ex. VIII. or by an electric fork.\n9","page":129},{"file":"p0130.txt","language":"en","ocr_en":"130\nE. 1V. Scripture,\ninterruption as it did before, he presses the key. After a few preliminary experiments for the sake of practice, the experimenter lowers the drum slightly (by the small handle at the top) after each experiment. Six records are taken.\nB.\tMeasuring the time estimate for two seconds. The contacts are placed at 8o\u00b0 apart and the experiments are repeated. Six records.\nC.\tMeasuring the time estimate for three seconds. The contacts are placed i2o\u00b0 apart. Six records.\nD.\tMeasuring the time estimate for four seconds. The contacts are placed i6o\u00b0 apart. Six records.\nComputation.\nCut off a piece of the time-line. Use it as a scale, reading the roths of a second and estimating the iooths. The records for i second are placed in the first column, those for 2 seconds in the fourth column, etc. The average is found for each column. The probable errors are also computed.\nLet the standard interval be indicated by T and the interval as estimated by t. Find the constant error c= t\u2014 T for each value of T. Thus for T= 1 sec. and / = 85, c = 85 \u2014 100 = \u2014 15.\nIn this way two series of values, the constant error c and the probable error r, are obtained for the series of values used for T'. Put c = f(T) and r = F (7), as explained in Ex. III. Plot the curves for these functions as explained in Ex. I. and II.\nPoints to be noted.\ni. Note the tendency to underestimate long intervals of time. Extremely short intervals are overestimated. 2. The reaction-time is not\n1 Results for 9 students in 1896 are given in the following table. In this case the time was measured from the beginning of the first tone to the beginning of the second.\n\ti Sec. Const. Aver. Prob.\t\t\tConst.\t2 Sec. Aver. Prob.\t\t3 Sec. Const. Aver. Prob.\t\t\t4 Sec. Const. Aver.\t\tProb.\n\terror.\tvar.\terror.\terror.\tvar.\terror.\terror.\tvar.\terror.\terror.\tvar.\terror.\nc\t+ 17\t13\t3-6\t+69\t8\t2.2\t+ 81\t20\t5.6\t+ 84\t26\t7-3\nG\t+21\t\u00bb3\t3-6\t\u201428\t20\t5-6\t\u201473\t12\t3-4\t\u2014109\t15\t4.2\n/\t\u201423\t10\t2.8\t\u201422\t36\t10. i\t\u201457\t50\t14.0\t\u2014 86\t40\t11.2\nK + i\t\t9\t2-5\t\u201452\t9\t2-5\t\u201470\t20\t5-6\t\u2014 49\t18\t5.0\n0\t\u201466\t4\t1.1\t\u201488\tJO\t2.8\t\u201428\t22\t6.2\t\u2014 5\u00b0\t28\t7.8\nP\t\u201423\t8\t2.2\t+41\t27\t7.6\t\u201463\t21\t5-9\t\u2014135\t42\t11.8\nR\t\u2014 7\tII\t3-1\t+27\t15\t4-2\t+ 3\t12\t3-4\t\u2014 7\t18\t5-0\nS\t+ 25\tH\t3-9\t+ 11\t28\t7.8\t-87\t8\t2.2\t\u2014 149\t18\t5\u00b0\n1\t\u201413\t12\t3-4\t\u201492\t21\t5-9\t+35\t62\t17-4\t\u2014104\t37\t10.4","page":130},{"file":"p0131.txt","language":"en","ocr_en":"Elementary course in psychological measurements.\t131\nto be subtracted from the second interval, because the subject involuntarily times his movement to occur at the point desired ; see Ex. XI.\nQuestions.\ni. These experiments are frequently referred to as being on the \u201c time-sense\u201d or \u201c time-consciousness.\u201d How would you define such a term scientifically? Compare Ex. IV (Point 2).\t2. What mental\ncharacteristics would be indicated by a large negative constant error and a large probable error ?\nExercise XIV\u2014Complex reaction-time.\n(Needed: pendulum chronoscope.1)\nApparatus.\nAn accurately adjusted double-bob pendulum is held by a catch at the right-hand side. The light pointer is caught on the projecting arm of the pendulum.\nThe chronoscope is first leveled by placing a spirit level on the base in a line parallel to the front ; the screws of the two fore-legs are turned till the bubble of the level is in the middle. The level is then turned at right angles, and the screw of the rear leg is turned.\nThe large milled head in front is turned clockwise as far as it will go, thereby closing the shutter and setting the reaction button at the back.\nWhen the experimenter presses the release at the right, the pendulum swings forward, releasing the shutter by striking a pin opposite the place where the pointer indicates zero. When the subject presses the reaction button, a horizontal bar behind the pointer clamps it to the scale. The graduation on the scale gives the time between the fall of the shutter and the pressing of the button. This scale is established by direct comparison with fork records on the drum in a manner similar to methods employed in Ex. VII. The figures on the scale indicate rooths of a second ; in this exercise the readings are to be in iooths, not ioooths.\nIn executing an experiment the pendulum is placed at the right, the pointer is carefully caught on it, and the milled head is turned. Red and white slips are inserted alternately in the vertical exposure wheel. The subject is comfortably seated with his finger on the reaction button ; he is to press the button as soon as the shutter drops. The pendulum is released and the experiment is made ; this is repeated until familiarity with apparatus and method is attained. The experimenter says \u201cNow\u201d about two seconds before each experiment.\n1 See Stud. Yale Psych. Lab., 1895, III 98, and New Psychology, Ch. IX.","page":131},{"file":"p0132.txt","language":"en","ocr_en":"I32\nE. IV. Scripture,\nThe individual experiments should be separated by about io seconds ; the groups by at least 30 seconds. When a group is begun, three or four experiments should be first taken without making any record of them. The subject must not know his results.\nExperiments.\nA.\tSimple reaction. The exposure wheel is turned so that a red slip is behind the shutter. The subject knows the color to be shown ; he is to press the button just as soon he sees it. Five records are taken ; the results are placed in the column \u00bb/,.\nB.\tReaction with discrimination. The subject is to react every time as before, but is to see the color distinctly before reacting. The experimenter at each experiment gives the exposure wheel a twirl, letting it stop on whichever notch it happens to strike. If it stops between two colors it is turned to the next notch. The presentation of the colors is. thus a matter of chance. Five records are made ; column mr\nC.\tReaction with discrimination and choice. The subject is to react only to red ; for white he is to remain still. The wheel is twirled as before. Five records are made. An account is also kept of the number of mistakes ; column m%.\nD.\tSame as C, but with reaction to white and rest to red column mr\nE.\tSame as B ; column tnt.\nF.\tSame as A, but with white instead of red ; column \u00bb/,.\nThe simple reaction time is composed of two mental processes, sensation and volition. The extra process introduced in experiments C. and E. is known as discrimination ; the average for tn, substracted from that for tn.t will give the discrimination time. The process introduced in B. and D. is known as choice ; the average for from that for m3 will give the time of choice.\nSpecimen record.\nm\\\t\t7'j2\tm2\tV%\t7' 2 \u20182\t\u00bb>3\t\tV\n21\t0.1\t0.01\t29\t0.1\t0.01\t35\t4-9\t24.01\n22\tO.9\t0.81\t3\u00b0\tI. X\tI.21\t34\t5-9\t34-81\n20\t1.1\tI.21\t29\t0.1\t0.01\t39\t0.9\t0.81\n22\tO.9\t0.8l\t28\t0.9\t0.8l\t41\t1.1\ti.21\n23\t1-9\t3.61\t27\t2.9\t8.4I\t32\t7-9\t62.41\n21\t0.1\t0.01\t29\t0.1\t0.01\t42\t2.1\t4.41\n21\t0.1\t0.01\t32\t31\t9.61\t37\t2.9\t8.41\n20\t1.1\t1.21\t35\t6.1\t37-21\t35\t4-9\t14.01\n20\t1.1\tI.21\t29\t0.1\t0.01\t3\u00b0\t9-9\t98.01\n21\t0.1\t0.01\t28\t0.9\t0.81\t44\t5-1\t26.01\n21.1\t\t9)8.9\u00b0\t28.9\t\t9)58-10\t39-9\t\t9)284.10\n\t\tI0)0.99\t\t\t10)6.46\t\t\t*0)31.57\n\t\t0.09\t\t\t0.65\t\t\t3.16","page":132},{"file":"p0133.txt","language":"en","ocr_en":"Elementary course in psychological measurements.\n133\n1/0.09=0.3\t1^0.65 = 0.8\t1/3.16 = 1.8\n2AXo-3 = o.2\t^X\u00b0-8 = o.5\t^Xx.8 = i.2\nSimple reaction-time : <7, = 21.1, r, = 0.2.\nReaction with discrimination: <73 = 28.9, r2 \u2014 \u00b0-5-\nReaction with discrimination and choice: <73 = 39.9, 73 = 1.2.\nDiscrimination-time, d=ai \u2014 <7, = 7.8.\nChoice-time, c = a3 \u2014 <z2 = II.o.\nPoints to be noted.\ni. The empirically established scale takes up the errors of the apparatus. 2. The results d and c are termed \u201cdiscrimination-time\u201d and \u201cchoice-time;\u201d these terms are tobe defined by giving the manner in which the results were obtained. They are not to be defined as the times required for the execution of two processes known as discrimination and choice which are defined in some other way. 2. We would expect that a3 \u2014 al \u2014 d+ c, but this will rarely happen in performing the exercise owing to unavoidable sources of error in the untrained subject.\nQuestions.\ni. What would probably have been the change in the results if the experimenter had arbitrarily placed the colors instead of allowing the selection by chance and if the subject had known this fact? 2. Why is the probable error larger for as than for a, ?\nExercise XV.\u2014Association-time.\n(Needed: pendulum chronoscope, cards with words, chin key, 2A extra-circuit battery. )\nApparatus.\na.\tPendulum chronoscope. See Ex. XIII. An electromagnet beneath the base is arranged to operate the reaction-key whenever the current is sent through it. The poles are at the posts marked C and D.\nb.\tCards with words. Two sets of small cards for the exposure wheel are placed beside the apparatus. One set is to be used by each experimenter ; it must not be seen by the subject ; therefore the boxes containing the sets are not to be opened until everything has been arranged for taking records.\nc.\tChin key. This is the modified telegraph key of Ex. IX., arranged for a break contact only, as in Ex. XII. It is mounted on blocks so as to be just below the chin of the subject. The current from the 2A battery is brought to the posts C, D. This causes the straight bar behind the chronoscope scale to clamp the pointer.","page":133},{"file":"p0134.txt","language":"en","ocr_en":"134\nE. IV. Scripture,\nThe back contact of the key is now similarly connected with the battery. As contact is made as long as the key is untouched, this acts as a \"shunt \u2019\u2019 and the current passes through the key (almost entirely) rather than through the longer and more difficult circuit of the magnet. Consequently the magnet does not act until the key is touched.1\nThe subject is comfortably seated so as to see the exposure opening. The key is adjusted to bear lightly against his chin.\nExperiments.\nA.\tSensory motor association. The experimenter opens the box containing the cards, and, out of sight of the subject, inserts one of them in the exposure wheel. When the shutter falls and exposes the word the subject is to repeat the word aloud, always emphasizing the chin movement so as to move the key knob. Three or four experiments are taken in order to give practice. Thereafter the wheel is filled with 10 new cards. Five records arc made.\nB.\tAssociation of ideas. Leaving the same cards in the wheel the sub-ect upon seeing a word is to call out the first other word that occurs to him. Several experiments are made for practice. Ten new cards are then inserted and five records are taken. After each record the pair of associated words is written.\nC.\tFill the wheel with ten cards more and make five records on association of ideas as in B.\nD.\tFill the wheel with ten cards more and make five records on sensory motor association as in A.\nComputation.\nFind the average and the probable error for each kind of association.\nIf we assume that in the association of ideas an extra mental process is directly added to the sensory motor association, the time for this process is found by subtracting the time for sensory motor association from the gross association-time as recorded.\n]Pints to be noted.\n1.\tNote that the larger characteristic variations, as compared with F.x. XIII, may indicate any or all of the following sources : i. complexity of the processes; 2. presence'of disturbing influences ; 3. vagueness in the definitions ; 4. inadequacy of the methods of experimenting.\n2.\tNote that the subject is not told to associate as quickly as possible.\n1 With a lamp battery the connections are made as in big. 7 ; the wires from socket G are brought to the magnet and those from socket C to the key.","page":134},{"file":"p0135.txt","language":"en","ocr_en":"Elementary course in psychological measurements.\n135\nQuestions.\nx. What is the relation between simple reaction and sensory motor association ?\t2. Why is the latent time of the magnet left undetermined?\nExercise XVI.\u2014Reproduction of a tone hy the voice.\n( Needed : 100 v. d. fork, spark coil, condenser, Puluj tube, simple switch, disc with graduated series of dots, manomctric flame with mouthpiece, motor with lamp board, 4A battery. )\nApparatus.\na. Electric fork. The current from the 4A battery is run through the fork in a manner similar to that for the battery through the fork in Ex. IX. To diminish the spark the poles of the condenser (Ex. IX) are connected to the fork at each side of the break, i. e., at the points closest to the platinum wire and the platinum disc. One of these points is the binding post at the back of the fork (it could not be closer without interfering with the vibration of the fork) ; the other is at a screw on the brass base supporting the platinun disc (not at the binding post at the end of the magnet wire).\n/>. Spark coil and Puluj tube. One of the wires is removed from the fork and brought to one of the primary poles P of the coil (Ex. IX) ; the other pole P is connected to the fork. The current thus runs through the primary circuit of the coil ; as it is interrupted by the fork 100 times per second, 100 sparks occur at the poles of the secondary coil.\nThe poles of the secondary coil are connected to the posts of a shunt switch (Ex. XII). Thread-like wires are led from this key to the poles of the Puluj tube.\nThe Puluj tube is a vacuum tube having between the electrodes a mica plate coated with a phosphorescent substance. When the short circuiting key is open, this surface gives a flash of light at every break in the primary circuit ; consequently, when the fork is vibrating, it flashes 100 times a second. If the flash is not strong, reverse the wires at the poles.\nc. Disc with dot scale. A disc of cardboard is marked with 21 rows of dots, each row differing from the next by one dot.1 The disc is placed on the axle of a motor, to which the current is supplied by a lamp-board, When the disc is put in rotation the dots fuse into a set of gray rings. The room is darkened and the Puluj tube is placed close to the disc so as to illuminate it. At a certain speed of the disc one of the rings will reappear as a series of dots at rest ; according to the laws of stroboscopic\n1 Fig. 19 is a reduced copy of the original disc which is 75 cm. in diameter. Although rather small, Fig. 19 can be cut out and used on the motor.","page":135},{"file":"p0136.txt","language":"en","ocr_en":"136\nE. JF. Scripture,\nvision there must then be 100 dots in that ring passing by the tube in one second. The neighboring rings will also break up into dots, but the dots will appear in motion ; those in which less than 100 pass per second will appear to move backward, while those in which there are more will move forward. It will sometimes happen that no ring will pass exactly 100 dots ; a touch on the axle will then slightly diminish the speed. The speed of the motor is adjusted by varying the amount of current.\nI'lc. 19.\nd. Manometric flame. Illuminating gas is brought to the front part of a capsule (Fig. 20) from which it issues as a small jet ; the size of this jet is regulated by a small stopcock. The back of this capsule is formed by a thin membrane. Back of this membrane is a small chamber opening into ajrumpet-shaped mouthpiece. Upon singing into this mouthpiece the membrane is made to vibrate by the vibration of the air producing the tone. The gas in the capsule is likewise set in vibration, whereby the flame alternates between maximum and minimum of size with every vibra-","page":136},{"file":"p0137.txt","language":"en","ocr_en":"Elementary course in psychological measurements.\nI37\ntion. These vibrations of the flame can be seen by moving the eyes suddenly sidewise. The vibrations produce periods of light and darkness just as in the case of the Puluj tube. Thus if a tone of roo vibrations be sung, there will be roo flashes per second. By holding the flame close to the rotating disc that series of dots can be picked out in which the number of dots passing corresponds to the number of vibrations in the flame.\nExperiments.\nThe experimenter is to pick out the roo row of dots, i. e., the one which appears to remain motionless when illuminated by the Puluj tube. The subject, holding the capsule in his hand, is to sing the same tone as the fork. While doing this he is to move the flame along in front of the disc until he finds the row of dots showing the number of vibrations in the tone sung. The experimenter records the number of rows by which this one differs from the correct one ; toward the center is \u2014, toward the outside +. A difference of x row means an error of i vibration in singing the tone.\nThe octave of the fork-tone is sung and the error is noted as before. A difference of one row means an error of two vibrations.\nTen records are made on each point. Averages and characteristic variations are calculated.\nExercise XVII.\u2014Color lag.\n(Needed : electric color wheel with speed indicator, black and red Maxwell discs, backing disc, circular scale and paper ring for discs, small telescope on Gauss tripod, battery of 2A, simple switch, 32 c. p. lamp, tape measure.)\nApparatus.1\na. Color discs. A red and black disc are slipped together by means of the radial slits. The backing disc is an unslit one which is placed\n\u25a0See Stud. Yale Psych. Lab., 1895 III 102, Fig. 17, for a view of the discs, motor, speed indicator and connections.","page":137},{"file":"p0138.txt","language":"en","ocr_en":"138\tE. JV. Scripture,\nbehind the others in order to keep the edges front flapping when they are rotated.\nb.\tColor 'wheel. The essential is a rapidly rotating axle with a screw-nut for fastening the discs against a flange. This is best obtained by using an electric motor. For the present exercise the motor is series-wound in order that its speed may be controlled by the amount of current. The current is brought to the two posts of the motor, passing in its way the two poles of a shunt switch. When the switch is closed the current passes directly across without going through the motor ; when it is open the current is forced to pass through the motor.\nc.\tSpeed indicator. The rotation of the motor axle causes the indicator arms to revolve and to fly outward. The extent to which they move outward depends on the relation of the speed of revolution to the weight of the arms and the tension of the restraining springs. A pointer is connected with the indicator to show just how much the arms move. The pointer moves over a scale graduated to show the number of revolutions per second. The scale was established empirically by spark-records on the drum, after the manner of Exercise IX, the place of the key in that exercise being taken by a revolving pin at the end of the axle striking against a metal spring.\nd.\tTelescope. This may be a simple tube blackened inside ; it limits the amount of the disc seen to a circle of definite area. Or a simple reading telescope of the usual kind may be used. It is placed on the tripod.\ne.\tAdjusting the apparatus. The nut is removed from the color wheel. The backing disc is placed on the axle. The red and black discs are slipped together, so that when rotated they will not catch the wind ; if the motor rotates counter-clockwise the edges must overlap to the right. The discs thus slipped together are placed on the axle, a small paper ring is placed in front and the nut is partly screwed up. The circular graduated scale is laid over the discs and they are moved till each occupies half the circle. The nut is then screwed tight.\nThe battery is turned on and the motor started.\nThe 32-c. p. lamp is lighted and placed at y2 meter in front and slightly below the discs.\nThe Gauss tripod is placed at a distance of x meter from the motor. The telescope is then adjusted so that the eye sees the whole field of view as a colored circle.\nExperiments.\nThe motor being at rest and the subject looking through the telescope, the experimenter says \u201c Ready \u201d and sends the current through the motor.","page":138},{"file":"p0139.txt","language":"en","ocr_en":"Elementary course in psychological measurements.\t139\nThe subject sees the color alternate with black, at first slowly, then rapidly. Soon they appear to mix, but still retain a flickering appearance. As the speed continues to increase, the flickering becomes less marked and finally diappears. At the moment when the illumination of the field appears to be constant and steady the subject says \u201cNow.\u201d The experimenter notes and records the position of the pointer at this moment.\nThe speed of the motor is allowed to increase considerably beyond the point just recorded ; the current is then turned off. The speed gradually decreases and at some point the illuminated field begins to flicker. At this point the subject says \u201cNow,\u201d and the experimenter notes and records the position of the pointer.\nRecords of the first kind may be called \u201cup-records,\u201d those of the other \u201cdown-records.\u201d The up-records are placed in one column, the down-records in another.\nAfter a few preliminary experiments to obtain practice, ten records are made of each kind.\nComputation.\nLet m be the average of the up-records and n that of the down-records. The time of one revolution in seconds is thus 1 fm, or i/n, and the time of half a revolution in ym or yn.\nLet the suppositions be made : 1, that the black was equivalent to absence of light ; 2, that there was no lag at the appearance of the red. It follows that since the red seemed to be present all the time, whereas it was present only half the time, the sensation must have persisted through the time of y2 a revolution, i. e., 2m or 2n sec., without any perceptible diminution of intensity.\nThe suppositions are not strictly according to fact. The black of the disc is not an absolute black, and there is a small lag at the beginning of the red sensation. For a bright red and a cloth black these errors may be neglected, as in the present case.\nBelow the records the following statements are to be made (all figures being in decimals to the 1/100 and the unit being seconds) : lag, up, =\t; lag, down, =\t; lag, average, =\t.\nPoints to be noted.\ni. The lag may be dependent on the intensity of the light and the area of the field. 2. The lag is a psychical and not a physical affair.\nQuestions.\ni. Would you add or subtract the latent time (or lag of the color at the beginning), if it were known and you wished the true time of lag? Why? 2. What is the unit of measurement in this exercise?","page":139}],"identifier":"lit28736","issued":"1896","language":"en","pages":"89-139","startpages":"89","title":"Elementary course in psychological measurements","type":"Journal Article","volume":"4"},"revision":0,"updated":"2022-01-31T13:29:13.432436+00:00"}