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{"created":"2022-01-31T12:59:01.745910+00:00","id":"lit28743","links":{},"metadata":{"alternative":"Studies from the Yale Psychological Laboratory","contributors":[{"name":"Scripture, Edward W.","role":"author"},{"name":"W. C. Crooke","role":"author"},{"name":"C. M. Warren","role":"author"}],"detailsRefDisplay":"Studies from the Yale Psychological Laboratory 5: 90-92","fulltext":[{"file":"p0090.txt","language":"en","ocr_en":"RESEARCHES ON MEMORY FOR ARM-MOVEMENTS.\nBY\nE. W. Scripture, W. C. Cooke and C. M. Warren.\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.\nThe 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.\nThe 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 widths of the finger, as all readings are to be taken from the end of the pointer.\nThe 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, d. 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 after an interval of t seconds the subject 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 record blank.\nIn a set of experiments carried out by Mr. Cooke in 1896-97 on four college students as subjects, the distances 100\"\"\", 300\"'\u201c and 500\"\u201d\u201d were investigated for the intervals 2% ioa and 20s. The constant and probable errors were calculated in the following way. If <r2, \u2022\u2022\u2022, an are the observations for given values of t and d, we have for the average\na = ai + at+ \u2022\" +\nn\nfrom which we obtain the constant error C=a \u2014 d.\n\u2022Scripture, Elementary course in psychological measurements, Stud. Yale Psych. Lab., 1896 IV 97; Scripture, New Psychology, 187, London 1897.\n90","page":90},{"file":"p0091.txt","language":"en","ocr_en":"Researches on memory for arm-movements.\n9l\nFor the variations, or errors, we have v = ay \u2014 a, vt = a2 = a, \u2014, vn=an \u2014 a ; from which we obtain the probable error for a single measurement by the shorter method\nn-0-3i*,i[ + 'V + - + l*,,.l\nn \u2014 i\nwhere | v I means that the sign of v is disregarded. The results for four subjects, A, B, C and D, are given in Table I ; five experiments were made on each point.\nTable I.\n6\tA\t\tB\t\tC\t\t\tD\n\u00a3\tC\tp\tC\tP\tC\tP\tC\tP\n2s\t+ 11\t5.8\t+ n\t8.9\t+ 2\t3-o\t\u2014 2\t8.9\nIO\t+ 22\t12. i\t+ i\u00b0\t8.9\t\u2014 10\t6.5\t\u2014 4\t7-1\n20\t+ 15\t12.5\t+ 15\t8.9\t\u2014 16\t2.4\t\u2014 4\t6.4\n2s\t+ 6\t12.8\t+ 10\t8.9\t\u2014 s\t11.2\t+ 9\t8.9\n10\t+ 6\t24.6\t\u2014 13\tH-9\t-30\t13-6\t\u2014 8\t16.9\n20\t\u2014 5\t14.5\t\u2014 13\t13.0\t\u2014 27\t17.6\t\u2014 12\t24.0\n2*\t+ 6\t7-4\t+ 7\t8-3\t\u2014 7\t12.9\t\u2014 5\t7.8\n10\t\u2014 2\t8.1\t\u2014 8\t7-5\t\u2014 i\t9-4\t- 15\t14.8\n20\t\u2014 i\t7-3\t\u2014 5\t7-5\t+ 6\t11.0\t\u2014 24\t21.7\nThe table seems to justify the conclusion that the law according to which the constant error varies in relation to the elapsed interval, is a purely individual matter, as was first pointed out by Scripture (New Psychology, 1S9).\nFig. 30.\nFig. 31.\nThe probable error also seems to follow no general law, although there are more cases in which it increases with the increase in interval than in. which it decreases or remains constant or fluctuates.","page":91},{"file":"p0092.txt","language":"en","ocr_en":"92\nE. IV. Scripture, IV. C. Cooke and C. M. Warren,\nFor comparison with these experiments on untrained observers another set was undertaken by Mr. Warren in March, 1898, in which the sub-\nfectwas the laboratory janitor, A. Fisher, a trained observer1 with no interest in the results. The constant error was calculated as before, but the probable error was derived by the more accurate formula\n\n+ l'\u00ef + \u2022\u2022\u2022+*\u201e\nthus 2oomm \u2014 15, 60, 45, 30, etc. in Figures 30, 31 and 32.\n\u00ab \u2014 i\nThe results for the intervals 15s, 30\", 45s and 60s and for the two distances 2oom\" and 300\"'\u201c are given in Table II. The first division for 200\"'\"\u2019 and that for3oo\"'m give the results when the experiments were made in the following order : 15\u201d \u2014 200, 300, 300, 200 ; 30\u2019 \u2014 200, 300, 300, 200, etc.\tThe other experiments on\n200\"\"\" were made on successive occasions, the distance being constant but the intervals of time being varied irregularly, The values of the table are expressed\nTable II.\n\t200mm\t\t\t200mu\u2018\t\t\t\t5oo,,,m\t\nTime.\tc\tp\t11\tc\tP\t11\tc\tp\tn\n15s\t\u201423\t173\t17\t\u2014 9\t16.3\t15\t\u201430\t21.8\t17\n3\u00b0\t+ 2\t30.2\t17\t\t21\tiS-5\t15\t\u201437\t159\t17\n45\t\u2014 9\t29.5\t12\t\u201420\t151\tiS\t\u201424\t31s\t12\n60\t+ i\t37-2\t12\t\u2014 9\t23.6\t15\t\u201447\t157\t12\nThese experiments seem to justify the conclusion that even for the same person the law of the constant error changes with the distance and with the method of the experiment. The probable error, however, is quite evidently an increasing function of the time-interval ; the experiments are, however, not extensive enough to justify an attempt at determining its law.\n1 Stud. Yale Psych. Lab., 1S96 IV 24.","page":92}],"identifier":"lit28743","issued":"1897","language":"en","pages":"90-92","startpages":"90","title":"Researches on memory for arm-movements","type":"Journal Article","volume":"5"},"revision":0,"updated":"2022-01-31T12:59:01.745916+00:00"}