"Doing Our Best:" A Qualitative Study of Researcher Challenges Administering Neuromodulation Across Different...

Noninvasive neuromodulation techniques such as transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS) are well-established neuroscience research tools. Because both rely on scalp contact, some have speculated that they may not work effectively across all hair types and textures. The present study investigated the presence of phenotypic bias in these technologies by interviewing TMS (n = 22) and tDCS (n = 16) researchers about their experiences administering them. The majority (71.1%) reported encountering difficulties administering neurostimulation due to research subjects' physical features, most frequently hairstyles common among Black research subjects. Half agreed that it is more difficult to administer TMS or tDCS to individuals from certain racial and ethnic backgrounds. Among participants who did not report difficulty, advance communication and screening was the most common strategy for avoiding challenges. Our findings provide empirical support for concerns about phenotypic bias in noninvasive neuromodulation; future efforts should identify and address factors underlying these difficulties.