by the Consulting Teams
at Brain Vision LLC and Brain Vision Solutions
To record a high-quality EEG signal, either the electrode or a conductive solution must make good contact with the scalp. This can be difficult to achieve in participants with certain hair types and styles, such as Black participants with thick natural hair leading to their disproportionate exclusion from studies. We offer tips to address these challenges and achieve more inclusive data collection pools.
Equitable representation of Black people within subject pools in non-invasive neurophysiological research is being more widely discussed (Choy et al., 2021). We recognize that there are many contributing factors that may lead to the exclusion of Black people from these studies. For this article, we will focus on electroencephalography (EEG) and share tips with current technology and methods for addressing or minimizing such exclusion.
Researchers who use EEG to study brain activity often work with fabric caps to ensure consistent placement of electrodes at specific positions on the scalp. Gel-based EEG requires application of a conductive solution to the scalp to help the electrical activity from the brain reach the recording surface of the electrode. If participants have natural, thick or curly hair, or certain hair styles (e.g., braids or locs), the EEG cap may not fit them well or the gel may have difficulty contacting the scalp. These factors may lead to poor EEG signal quality, and the participants may have to be excluded from the study, contributing to a poor representation of the actual demographics of the community.
Many labs have reached out to us asking for recommendations on how to make EEG more accessible, specifically to Black study participants.
We hear you …
Based on our experience and feedback from researchers who use our equipment, we have collected some suggestions to help optimize the setup when recording EEG from people with thick or curly hair with our actiCAP gel active electrodes. We share this list of tips in hopes of continuing the larger discussion among EEG researchers about ways to reduce the exclusion of Black participants in research studies.
- Ask the participant to leave their hair natural, dry, and product-free on the day of the recording. Make sure to give them as much advanced notice as possible and consider sending out a reminder a week and a few days before the scheduled recording. It is important to appreciate that hair care and styling can be a much more involved process for some participants than others.
- Explicitly ask the participant not to use conditioner, even the day before.
- Remember that makeup and natural oils are insulators — use alcohol or makeup removal wipes to clean the skin at electrode positions not covered by hair (e.g., the Fp row, especially where the ground electrode is located).
- Consider using a more liquid gel (e.g., “Lectron III”) to better reach the scalp. Be mindful of gel bridges in a higher density setup.
- Consider the type of syringe tip that will best enable you to part hair. We offer several types of gel dispensing tips, in different gauges and materials. The 16-gauge, 1-inch blunt metal tips may sometimes be optimal.
- Allow the gel time to settle and soak through hair and into the skin. This will not necessarily happen right away — give yourself 5-10 minutes for the gel to contact the scalp.
- If the participant has thick locs, braids, weaves, etc. that block the exact electrode positions you need to record from and cannot be removed, there is, unfortunately, not much you can do in the moment of a recording, and the participant may need to be dismissed. However, the idea of creatively braiding around positions that will be used for recording EEG is one approach that some labs have investigated with positive results. We also offer different-sized empty fabric caps that have EEG positions marked, which participants could use in the lab or at home to see if their hair styling positions keep the locations of interest available for recording.
There have also been several labs working on defining best practices in this space, one of which is based out of UCF in Florida. There is also a recent roundtable discussion hosted by Black in Neuro, featuring EEG researchers and Black hair stylists here:
We are always looking for ways to help researchers with improved solutions, and we strive to make EEG more accessible and inclusive for all study participants. We know that we can do better. If you have any other suggestions, please share them with us! We look forward to your feedback.