Lecture 5 - SCR Measurements and Artefacts

Question 1

Name four types of possible artefacts when measuring SC:

Answer 1

• Short-circuit
• Loose electrodes
• Motion artefacts
• 50 Hz interference

Question 2

Explain the artefact; short circuit

Answer 2

Happens when there is direct contact between electrodes; resistance becomes zero; conductance becomes infinite

Also happens when there is water in between the electrodes
Conductance is high alright, but of course not skin conductance anymore

Question 3

Explain the artefact; loose electrode

Answer 3

When there is no contact between the electrode and the skin, the resistance will be infinite, and therefore the SC will be zero

This can happen when an electrode has come loose. But also when you take of the electrodes after a measurement, or when you take off the wristband when showering for example.
Mobi shows a very negative number as a warning

Question 4

Explain the artefact; motion

Answer 4

You see very steep changes in the SC response

Usually filtered out of omitted from the data

Question 5

Explain the artefact; 50 Hz interference

Answer 5

Another electrical signal close to the measurement location can interfere. You clearly see a thick layer over the original skin conductance response

Can be filtered out by for example averaging over 20 milliseconds