Owner’s Guide
25
second subject zero before commencing measurement. The galvanic skin response to a
stimulus or series of stimuli can then be measured, relative to the baseline conductivity.
To GSR Amp
Increased arousal due to physical or emotional stimuli increases conductivity. Typically,
there is a short time lag, followed by a sharp increase and an exponential decay to
baseline level. The whole response may take up to 40 seconds, although the decay
phase is highly dependent on the subject.
The response is not fast, so a recording speed of 4 samples per second is adequate for
most purposes. Good stimuli for evoking the response include a sudden loud noise (as
shown in Figure 8–7), or a full inhalation, two second breath hold, then full exhalation.
Figure 3–6
Connecting the
electrodes to
the subject: the
GSR Amp uses
AC excitation, so
the polarity of the
connections is
unimportant
Figure 3–7
A typical GSR
response to a
startle stimulus,
recorded from the
palmar surface of
the fingers
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