Shimmer3 GSR+ (Galvanic Skin Response)

Our skin reveals a lot of information on how we feel when we are exposed to emotionally loaded images, videos, events, or other kinds of stimuli – both positive (“aww, how cute!”) and negative (“yikes!”). No matter whether we are stressed, nervous, fearful, psyched up, stoked,
baffled, or surprised – whenever we are emotionally aroused, the electrical conductivity of our skin subtly changes. One of the most sensitive measures of emotional arousal is Galvanic Skin Response (GSR), also referred to as Electrodermal Activity (EDA) or Skin Conductance (SC).

What makes GSR such a valuable biometric signal in assessing emotional behavior?
With GSR, you can tap into unconscious behavior that is not under cognitive control. Skin conductivity is solely modulated by autonomic sympathetic activity that drives bodily processes, cognitive and emotional states as well as cognition on an entirely subconscious level. We simply cannot consciously control the level of skin conductivity. Exactly this circumstance renders GSR the perfect marker for emotional arousal as it offers undiluted insights into physiological and psychological processes of a person.

Application field of GSR
With GSR, the impact of any emotionally arousing content, product or service can be tested – actual physical objects, videos, images, sounds, odors, food probes and other sensory stimuli as well as thought experiments and mental images.

The logic behind GSR is very simple:
1. Place two electrodes on emotionally sensitive body locations
2. Apply a constant low voltage
3. Measure the electrical current between the two electrodes
4. Report the associated skin conductance

What about the sampling rate?
Although GSR data might be acquired with arbitrary sampling rates (up to 2000 Hz), very low sampling rates are sufficient. We suggest sampling rates from 1 to 10 Hz, however, keep in mind that higher sampling rates might be necessary if the same device collects GSR and other physiological parameters such as (optical) heart rate, for example.

Sensor placement

While sweat glands are present in almost all parts of the body, certain areas respond more strongly to emotional stimulation. Particularly, the palms of the hands, fingers and foot soles are sensitive recording sites.
Which location should you choose for your recording?

For more information see Shimmer User Manual and Pocked Guide – Galvanic Skin Response.

Also see Consensys – GSR software for information about the software.