. Thinking, feeling, doing . tone movement makes a change in the position of thepointer. The tone-tester is compared beforehand witha carefully tuned piano to determine the position of thepointer when the pipe gives A of concert pitch. Thisposition is marked at A 435 in the illustration. Thefigures mean that at this point the whistle makes a tone of435 vibrations per second. In the same manner the suc-ceeding notes are settled. The spaces are then subdi-vided by the eye into thirty-seconds of a tone. To make the experiment, the pointer is placed at Aand the pipe is blown for an inst
. Thinking, feeling, doing . tone movement makes a change in the position of thepointer. The tone-tester is compared beforehand witha carefully tuned piano to determine the position of thepointer when the pipe gives A of concert pitch. Thisposition is marked at A 435 in the illustration. Thefigures mean that at this point the whistle makes a tone of435 vibrations per second. In the same manner the suc-ceeding notes are settled. The spaces are then subdi-vided by the eye into thirty-seconds of a tone. To make the experiment, the pointer is placed at Aand the pipe is blown for an instant. The pointer is thenmoved upward one mark, and after about two secondsthe pipe is again sounded. The person experimentedupon tells if he hears a difference. The experiment is repeated, startingwith A every time,till a difference isheard. In a similarmanner the differ-ence below A isfound. In experimentsmade on a number ofNew Haven schoolchildren the accu-racy in detectingdifferences wasfound to increasewith aore. The re-. 78. Error in Hearing Decreases with Agefrom 6 vears (at the left) to 19 years(at the right). suits are shown in Fig. 78. The distance along the bot- Hearing. 143 torn indicates the age, beginning at six and ending atnineteen. The distance upward indicates the number ofthirty-seconds of a tone that could be detected. Thesmaller the number, the lower the irregular line and themore acute the childs ear. There is another and perhaps more important threshold Threshold ofto be found than the threshold of difference, namely, the c angethreshold of change. Almost all the experiments ofpsychologists have been confined to the threshold of dif-ference ; I have lately called attention to this thresholdof change and to the fact that it is an entirely differentthing from the other. The threshold of change can be illustrated by startingthe tone at A and raising or lowering it continuouslytill a difference is noticed. I have succeeded in provingthat the least perceptible
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectpsychop, bookyear1895
