Every time our brain reacts to something emotionally our body has a tiny sweat response (the skin response). By measuring this effect we are able to interpret reactions that our test subjects might not even be aware of themselves. Based on this we can suggest improvements for whatever was tested, to remove or limit the negative emotional trigger, and create a more enjoyable user experience.

< Bild på skin conductance-graf. >

How does it work?

The brain always tries to conserve power. To do this the autonomic nervous system in the body adjusts the activity level to be suitable for the environment. Not more – not less. In situations of stress, the “fight or flight” system, the sympathetic nervous system, is activated. You can compare this to the body’s throttle pedal. The body gets ready to be active and among other things, this increases activity in the sweat glands. Since sweat is salt-water and salt conducts electricity – the better the skin conducts electricity, the higher activity in the autonomic nervous system.

The other part of the autonomic nervous system is the body’s break pedal. It is called the parasympathetic system and it lowers the body’s physical readiness, and instead concentrates energy to digestion, repair functions and rest.

shimmer gsr sensor
The skin response sensor is a small wireless device that continously measures stress reactions. The sensors are usually placed on two fingers and are easily forgotten by the test person.

Why do we use it?

By measuring a person’s electric conductivity in the skin we can follow the body’s “throttle and break”-response to stimuli. For example we can find situations with an accuracy of +/- one second when the brain steps on the gas pedal. This enables us to find out when a person’s brain reacts to something. Together with screen recordings, eye tracking and interviews we can find out if there was an issue in the interaction with the system we are testing.

What’s in it for you?

Normally you would not want to cause your user to react negatively during interaction with a system, so this is valuable information in a wide range of applications. It enables us to suggest improvements to issues that otherwise might go unnoticed but still cause a negative user experience.