Measurement of " Emotive " Physiological Changes. 215 



For this purpose there were projected upon the screen : — 



1. On the upper scale the galvanometer spot, arranged to move to the 

 + side with increased electrical conductivity due to emotional excitement 

 (and returning to the — side with diminishing conductivity accompanying 

 the subsidence of excitement). 



2. On the lower scale the shadow of a delicate myograph to sliow the 

 fluctuations of muscular contraction. 



For the purpose of the demonstration, strong (disagreeable) stimuli are 

 used, viz. : — 



1. An unexpected loud sound (motor horn). 



2. An expected bum (lighted match under hand, the striking of the match 

 being, if possible, utilised as the warning signal). 



3. A disagreeable pungent smell, under control of subject. 



4. A painful thought, in some degree under control of subject. 



Method. — Simultaneous photographic records of the movements and of the 

 electrical resistance (skin) are taken from the extremities (hands and feet) of 

 a subject as quiescent as possible. The subject reclines in an armchair 

 reading an unexciting book, and often becomes somnolent ; a stimulus 

 calculated to arouse "emotion" is now made and signalled on the records. 

 The muscle recorder is of sufficient delicacy to show the pulse, and to 

 respond to the slightest unconscious movement. The electrical circuit 

 consists of an accumulator cell (2"o volts), or of 2 Leclanch^ cells (2'8 volts), 

 two galvanometers, a resistance (1,000 or 10,000 ohms) that can be put 

 in or out of circuit for the purpose of calibration, and the subject of obser- 

 vation, with impolarisable electrodes applied to tlie dorsal and palmar 

 surfaces of the hand or of the foot. 



The galvanometric spot of light indicative of current strength wavers under 

 the influence of fluctuations of imbibition, and of contact pressure with slight 

 (unconscious) muscular movement, but also, and quite independently, with 

 altered states of consciousness, especially with such alterations as are 

 sufficiently intense to be attended with subjective, or it may be objective, 

 signs of emotion. 



The effect is best demonstrated on the hand or foot ; on other parts 

 (forearm, arm, leg, thigh) under similar conditions it is imperceptible. As 

 regards the hand and foot, the palmar surface is effective, the dorsal 

 surface ineffective. 



Results. — From these facts a correlation with the presence of sweat glands 

 suggests itself. 



