My signal looks flat. What does it mean?

If it’s flat when you first put the sensor on, then it may be that the electrodes/skin/air are very dry and you need to do something activating for a while to build up some moisture between the skin and the electrodes.

Once you’ve seen SCR’s and you’re sure that everything is working, and the sensor hasn’t moved to a new position, then a flat signal could mean the individual is in a state of rest or is stabile. Stabile is common for some individuals who simply produce fewer SCR’s or who habituate rapidly to repeated presentations of simple stimuli.

Also, it is possible that a person is taking medications, such as anti-cholinergics, or others that can suppress the sympathetic nervous system. If so, the skin conductance can be very low (below 0.05). Very dry skin in need of moisturizing can also make it hard to get a good reading. Also, some conditions can be associated with having low skin conductance; for example, many people with ADHD also have very low skin conductance.

Finally, sometimes when you look at your data in the Q software, which auto-scales the vertical dimension, it will look flat because you may have a huge (but invisible) noise spike that is causing the scale to be really large compared to most of the data (“also see How to Easily Adjust Vertical Scaling”).