EDA (GSR) subject preparation

BIOPAC offers a variety of setups for recording electrodermal activity, including

• Reusable: skin conductance transducer (MP150+TSD203 or MP36+SS3LA) and electrodermal gel (GEL101).
• Disposable: MP150+EDA100C amp with 2 x LEAD110A or MP36+SS57LA EDA lead let plus pre-gelled EDA electrodes (EL507).
• Wireless or Logged: BN-PPGED amplifier or BN-LOGGER+BN-PPGED-T transmitter plus BN-EDA-LEAD2 and pre-gelled EDA electrodes EL507.
• MRI: EDA100C-MRI amplifier with MR-conditional leads (2 x LEAD108B 15 cm or LEAD108C 30 cm), radio-translucent electrodes (2 x EL509 dry electrodes), and electrodermal gel (GEL101).

The following general guidelines will improve the quality of data from any setup:

1. Never abrade the skin.
   • Note: For MRI setups, lightly abrading the skin may sometimes help if the subject has particularly calloused fingers. Still, this is not recommended and should be used as a last resort only. See MRI Guidelines for additional information.
2. If you clean the electrode site, do it with water for all subjects.
3. Make sure you have enough gel on the electrodes. (Dry disposable electrodes will result in a deteriorated signal. Follow the storage guidelines for the electrodes to prevent them from drying out)
4. Use isotonic gel. (If using disposable electrodes and they appear dry you can still use them by applying isotonic gel as long as the dry gel on the electrodes has not crystallized)
5. Attach the electrodes 5-10 minutes before recording.

• To confirm whether they are making good contact ask the subject to take a deep breath and hold it for a few seconds. This will usually result in a skin conductance response (see Deep breath and SCR/EDA (GSR) increase).

For more detailed information, see Guidelines – EDA, EDR, GSR, SCL, and SCR.