PSYCHOLOGICAL PROGRAM AND TECHNIQUE. 



187 



circuit is opened every 2 seconds by the swing of the pendulum in a 

 large Seth Thomas clock. When the clock pendulum opens the con- 

 tact in the primary circuit, a spark from the tip of the metal pointer 

 dislodges the smoke in the immediate vicinity on the kymograph 

 paper, and so incorporates time intervals directly with the record. 

 The speed of the kymograph drum D was 50 mm. per second, and as 

 its periphery represents the distance of 500 nmi., it was convenient 

 to make the finger-movement series 10 seconds long. Movements 

 were counted in five 2-second blocks. Three series of movements 

 were recorded, with a rest interval of at least 1 minute. Ten sec- 



FiG. 53. — Schematic representation of apparatus and hand in position for recording finger 



movements. 



S, support for wrist and arm; P, post to be gripped; F, finger connection to recording point, iJ, 

 by insulation material, W; T, induction apparatus of commercial design with high tension 

 winding connected to kymograph drum, D, and metal recording point, R; C, penduluna of 

 large clock to break primary circuit of transformer and so, by the jump sparks, record time 

 directly on the finger movement record. 



onds at maximum finger movement speed is not so long as to be 

 fatiguing. The subject was allowed to use whatever amplitude of 

 movement he thought consistent with his best performance. The 

 tracing was to be a record of finger movements and not of hand or 

 arm movements. For this cause the subject was instructed to grip 

 the post P rather tightly. The first and second fingers of the hand 

 were moved together simultaneously, a form of movement which 

 Langfeld^ has shown favors the greatest speed. Sections of finger- 

 movement records may be seen in figure 29, page 158. It was 

 experimentally expedient to place the finger-movement records on 

 the same kymograph sheet with the others taken in room B. They 

 could be traced over the word reactions without causing any particular 



1 Langfeld, Psychol. Review, 1915, 22, p. 453. 



