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{"created":"2022-01-31T15:36:14.367060+00:00","id":"lit23167","links":{},"metadata":{"alternative":"Studies from the Yale Psychological Laboratory","contributors":[{"name":"Scripture, E. W.","role":"author"},{"name":"John M. Moore","role":"author"}],"detailsRefDisplay":"Studies from the Yale Psychological Laboratory 1: 88-91","fulltext":[{"file":"p0088.txt","language":"en","ocr_en":"A NEW REACTION-KEY AND THE TIME OF VOLUNTARY MOVEMENT\nBY\nE. W. Scriptitbe and John M. Moore.\nIn an article on the skin-sense1 Dessoib describes an arrangement for use in place of the ordinary telegraph-key in investigating reaction-times. In addition to the gain in convenience he claims that the varying results obtained for sensory and muscular reactions are due to the effect of the construction and manner of use of the ordinary key on the time of executing voluntary movements.\nAt the request of Prof. Titchener of Cornell University a rough copy of Dessoir\u2019s arrangement was made in our laboratory workshop. It became evident that this arrangement possessed only one good quality, that of portability ; with it the arm and hand did not need to be upon a table as with the - telegraph-key but could be placed in any comfortable position. With this exception all the disadvantages of the telegraph-key were retained and some further ones added.\nThe advantage of portability is so great that the problem of the invention of a key that could be used in any position was undertaken. At the same time certain faults of the telegraph-key were to be avoided. There was to be no spring ; the key was to act on the make or the break or on both ; each contact was to be applicable to either a flexion or an extension movement.\nThe problem was solved with success. The final form in which the key was made, is shown in fig. 30.\nTwo hard-rubber slides run on steel guides. The upper slide has a hole to fit the end of the finger. The other has an inclined hole for the thumb, for use when the key is held by the thumb and finger alone. When the key is rested on anything or is held by the other hand, the thumb may be placed against the projecting arm ; this arrangement gives a somewhat easier action, as the finger moves more naturally in a plane inclined to that passing through thumb and finger.\n1 Dessoib, \u00fceier den Hautsinn, Du Bois-Beymond\u2019s Arch. f. Physiol. 1893 309.","page":88},{"file":"p0089.txt","language":"en","ocr_en":"New reaction-key and voluntary movement.\t89\nThe binding-post shown at the top carries a platinum contact ; that on the upper slide is connected with a contact at each side of the slide ; that on the lower slide is connected with a contact pointing upward. The lower slide is fastened at any point by a clamp whose screw is seen to the left in the figure. This determines the range of movement of the upper slide.\nThe upper slide can make contact at either extreme of its movement. One wire is always carried to the binding-post on the movable slide. To have a break-circuit record with a flexion movement, the other wire is carried to the top binding-post ; the thumb and\nFig. 30.\nfinger are held apart at any desired distance ; at the least movement of the finger the current is broken. For a break-circuit record with extensor movement the other wire is carried to the post in the fixed slide ; the finger is bent till the slides touch. For make-circuit records the lower contact is used with the extended finger, the upper with the bent finger. As the excursion can be made very small by adjustment of the lower slide, the lost time for make-records can be reduced to a minimum.\nNo spring for holding the contacts is needed. The movable slide is brought into position by the finger and will retain its contact without pressure until disturbed.\nWhile using this key in an exercise on the rapidity of tapping movements of the finger we found that we had the means at hand of making new investigations on the time and extent of voluntary","page":89},{"file":"p0090.txt","language":"en","ocr_en":"90\nNew reaction-key and voluntary movement.\nmovement. All previous work in recording taps had been done with an ordinary telegraph-key by which only the moment of the extremity of the downward movement was recorded. By simply connecting the binding-posts of the cross-piece and the fixed slide to one end of the circuit and the post of the movable slide to the other, a record was made of the downward extreme, the upward extreme and the period of rest at each extreme. Moreover, the adjustment of the fixed slide gave any desired extent for the movement.\nThe method of recording was that described by Bliss on pages 7-10. The key was placed in the primary circuit of the spark-coil and the secondary circuit was sent through the drum and fork. A 500 fork was used, each half-wave indicating lff. A spark-record was made of the kind shown in fig. 6. Records were counted in thousandths, no account being taken of fractions of a half-wave.\nThe subject of experiment, J. M. Moore, was placed in the isolated room described on pages 2 and 71. The arm rested easily on a table of convenient height. A rod clamped to the table acted, as a support for the hand. The rod was grasped by the fourth and fifth fingers, whereby the motion of other muscles than those of the fore finger and thumb was in the main prevented. Three distances were chosen through which the slide was to move, namely, 5mm, 10mm and 20mul. Two series of experiments were made on each distance. The results were combined into the accompanying table.\nTABLE.\nDistance\tE\tMV\tF\tMV\tc\tMV\tn\nPjmm\t33\t4\t48\t8 '\t81\t9\t70\n10\u201c\u201d\u201d\t40\t5\t48\t9\t88\t9\t60\n20\"\"\"\t53\t4\t37\t5\t90\t5\t40\nIn this table E indicates the average time of the extensor movement, F that of the flexor movement, C that of the complete movement, MV the average deviation and n the number of records in each case.\nWith the distance of 5inm the extensor movement required less time than the flexor movement and was much more regular. With 10mm","page":90},{"file":"p0091.txt","language":"en","ocr_en":"N\u2019\u00e9lu reaction-key and voluntary movement.\t91\nthere was a similar, but smaller difference ; the limits of average deviation show that in many cases the slower extensor movements took longer than the faster flexor-movement. With 20mm the flexor movement was much more rapid than the extensor movement. It is evident that the point at which they require the same time lies somewhat above 10I,l,n.\nThese results can perhaps be explained in the following way. When the key was in position the middle finger was placed on the upper cross-piece while the fixed slide was held by the thumb. So whatever the distance, the fore-finger was always brought back to the same bent position. Now, when the distance is very small the finger is never fully extended ; thus the extensor muscle has abundant leverage to do a little work in a very short time, while the flexor is not so favored. As the distance increases the flexor slowly gains its power\u2014slowly, because it had never been bent enough to obstruct its movement materially. But while the flexor is slowly increasing in strength, the extensor is losing quite rapidly, for only a few centimeters will fully extend the finger so that its whole power will be lost. When the distance is 10mm the two powers are nearlv equal, but with the excess in favor of the extensor. At 20'\"m the balance of power has changed, and the extensor is so near the end of its strength as to show clearly in the results.\nA curious result of the gain in one muscle and the loss in the other is the fact that the total time of vibration, or tapping, varies only about 10 per cent, for distances standing in the relation of 1 to 4.\nThe time of rest was quite different at the two positions. At the end of the extensor movement the make-spark and the break-spark indicated a period of 2n to 3CT, occasionally 4ff. At the end of the flexor movement the time of rest was so short that seldom more than one spark was present, indicating a time too short for detection.\nIn looking over the single records it was found that the time of movement was much more regular than the introspective observation had indicated. At times the observer seemed unable to move the muscle ; some unusually long times are found in the record but not so often as the observer supposed.","page":91}],"identifier":"lit23167","issued":"1892-1893","language":"en","pages":"88-91","startpages":"88","title":"A new reaction-key and the time of voluntary movement","type":"Journal Article","volume":"1"},"revision":0,"updated":"2022-01-31T15:36:14.367066+00:00"}