PULSE DURING MENTAL AND PHYSICAL WORK. 189 



TECHNIQUES FOR RECORDING THE PULSE DURING PSYCHOLOGICAL 



EXPERIMENTS. 



Three devices were used for obtaining the pulse-records during our 

 experiments: (1) The temporal pulse was recorded by a skeleton 

 telephone-receiver in series with the string galvanometer. (2) During 

 the association experiments the radial pulse was recorded by means of 

 a new electric sphygmograph which was devised to record on a distant 

 kymograph. The electric relay was operated first by the Wiersma 

 hand plethysmograph and later by a Tigerstedt bulb. (3) Except for 

 the association experiments, all our later records were electrocardio- 

 grams from body leads through condensers. 



TELEPHONE PULSE-RECORDER. 



The telephone pulse-recorder was first described by Dodge. 1 In 

 principle it consists of a skeleton telephone-receiver attached to the 

 head, so that the diaphragm or armature rests on the temporal artery. 

 Vibrations of the armature in the field of the small permanent magnet 

 of the receiver set up minute electric currents in the surrounding high- 

 resistance coils. These currents are recorded by the aid of the string- 

 galvanometer. Difficulties of adjustment and disturbances due to 

 sudden movements of the head led to the substitution of the electro- 

 cardiogram for the pulse-recorder in all pulse-records which were taken 

 subsequent to March 26, 1914. 



CONSTRUCTION AND OPERATION OF AN ELECTRICAL SPHYGMOGRAPH FOR 

 RECORDING PULSE-RATE AT A DISTANCE. 



In connection with the experiments on association, it was regarded 

 as desirable to have as complete records of physical condition as was 

 practicable. Among other data it seemed desirable, for reasons that 

 we have already mentioned, to take continuous pulse-records through- 

 out the entire association experiments. 



As the laboratory was equipped at the end of our year's work, it 

 would have been relatively simple to provide for such continuous pulse- 

 records by the use of the electro-cardiogram from body leads, our third 

 method. When the association experiments were first commenced, 

 however, we were not in a position to take photographic records of the 

 pulse which were longer than 20 cm. Moreover, if the individual 

 pulse-cycles were to be given sufficient length on the record to permit 

 accurate reading, photographic records would be an expensive tech- 

 nique. It is doubtful if the advantage of the method would have 

 warranted the additional expense. 



Ordinary direct methods of sphygmography are available only when 

 the subjects are situated in the immediate vicinity of the recording 

 apparatus. In all psychological experiments such proximity to the 



, Psychological Review, 1913, 20, p. 1. 



