Exhibit 15.21 Shimmer GSR sensor. (Source: iMotions).
A GSR sensor is a non-invasive device that requires minimum
preparation and calibration. The operation is fairly straightforward. Two electrodes are placed
where there is high density of the eccrine sweat glands, such as fingers, palms or the soles of the
feet. A low voltage is applied, and the skin conductance is computed by measuring
the current flowing between the electrodes.
The fingers, palms and foot soles are the parts of the body that respond to emotional and other psychological stimuli.
As shown in Exhibit 15.21, the middle and index finger are ideal locations to place the electrodes, typically on the non-dominant
hand so that respondent is free to use the dominant hand.
If respondents need to use their fingers, such as for typing, then the palm is an option, or else the inner side of
the sole of the foot.As can be seen from the exhibit, the electrodes are mounted on Velcro
straps. The device is easily worn by fastening the straps.
In addition to the electrodes, the device comprises of an amplifier to boost the signal
and a digitizer to convert the analog signal to digital.
