  Mental Imagery based Brain-Computer Interfaces (MI-BCI) are a mean to control
digital technologies by performing MI tasks alone. Throughout MI-BCI use, human
supervision (e.g., experimenter or caregiver) plays a central role. While
providing emotional and social feedback, people present BCIs to users and
ensure smooth users' progress with BCI use. Though, very little is known about
the influence experimenters might have on the results obtained. Such influence
is to be expected as social and emotional feedback were shown to influence
MI-BCI performances. Furthermore, literature from different fields showed an
experimenter effect, and specifically of their gender, on experimental outcome.
We assessed the impact of the interaction between experi-menter and participant
gender on MI-BCI performances and progress throughout a session. Our results
revealed an interaction between participants gender, experimenter gender and
progress over runs. It seems to suggest that women experimenters may positively
influence partici-pants' progress compared to men experimenters.
