Admittedly, setting up a biometric study can seem intimidating at times – a complex experimental design, new respondents, demanding technologies along with an ambitious timeframe. All while pushing for high-quality results.
We have good news. The answer to meaningful data is not wrapped in mystery. Way before data recording, high data quality starts with creating a suitable physical framework for your study. But – what does “suitable” mean exactly?
Undoubtedly, one question that we are frequently asked involves the dos and don’ts of study setups. Reason enough for us to hook you up with everything you need to know to create the optimal environment for your biometric research in a dedicated series of blog posts.
Are you in for strikingly good data? Great! In this week’s blog post we put galvanic skin response (GSR) under the microscope and reveal 11 tricks that will help you boost your GSR data to the max.
Let’s get to them now.
First things first: Preparing the physical environment for GSR
- Ideally, place the sensors on the fingers (or fingertips) of the dominant hand. However, if the task requires your respondents to use the dominant hand during performance (moving the mouse while responding to on-screen stimuli, for example), place the sensors on the non-dominant hand instead.
- If your respondents have to use both hands during recording (while interacting with objects in real-life environments, for example), attach the sensors to the inner side of the foot. As the soles of the foot are highly subjected to pressure while standing or walking, make sure to place the sensors on a medial site on the inner side of the foot.
- To guarantee accurate biometric measurements, the sensors need to be connected to the body at all times throughout the experiment. Ensure the sensors are placed firmly on the fingers (or foot).
- For better grip, you may as well apply adhesive electrode pads filled with conductive gel in order to avoid slippage from the recording sites.
- Speaking of recording sites: Spare yourself unpleasant surprises and be consistent with sensor placement. Use the same location across respondents for the entire study, and do not switch recording sites during or between recordings.
- Limb movement: Admittedly, it’s sheer impossible to eliminate body movements entirely during recording. However, try to arrange for a physical environment that allows to keep body movements (especially those of the limbs from which GSR is recorded) to a minimum as they can significantly distort the GSR signal. One key element to keep unwanted movements at bay is to make your respondents feel at ease. Ensure they are seated comfortably (click here to read more on seating comfort during studies) and instruct them in the best possible way where to put their hand while task performance to avoid unnecessary movements out of discomfort and uneasiness.
- Breathing: Your respondents should breathe normally during recording. Make sure they do not hold their breath or breathe irregularly (we recommend to record the respiration curve in addition to GSR in order to enable a later elimination of artifacts caused by irregular respiratory activity). Why? Excessive breathing or holding of one’s breath results in slow drifts in the GSR data. This could easily be misinterpreted as punctual bursts reflecting increased arousal of your respondents. Not so great.
- Talking: Talking and chatting should be avoided during electrodermal recording whenever possible as it most likely will affect measurement precision.
Make sure your receiver (laptop, dongle etc.) actually receives a clear sensor signal. There are some things to keep in mind that potentially can interfere with the sensor signal and cause the connection to drop. Have a look.
- Hand placement: Placing the hand (with sensors attached) underneath a desk (on the thigh, for example) might interfere with the sensor signal, even if the hand lies steady and doesn’t move. To avoid this kind of obstruction, ensure the sensors have direct connection to the receiver.
- Human body: The human body constitutes one possible source of irritation. To avoid any unnecessary interference with the signal, make sure no other person is sitting or standing between the sensors and the receiver.
- Bluetooth activity: Bluetooth activity is one further interference factor. As it can cause sensor signal dropping, disable all connections that are not needed during the recording session.
Contact our experts at iMotions to receive more hands-on advice on boosting your GSR data and learn more on biometric research.