  With stereoscopic displays, a depth sensation that is too strong could impede
visual comfort and result in fatigue or pain. Electroencephalography (EEG) is a
technology which records brain activity. We used it to develop a novel
brain-computer interface that monitors users' states in order to reduce visual
strain. We present the first proof-of-concept system that discriminates
comfortable conditions from uncomfortable ones during stereoscopic vision using
EEG. It reacts within 1s to depth variations, achieving 63% accuracy on average
and 74% when 7 consecutive variations are measured. This study could lead to
adaptive systems that automatically suit stereoscopic displays to users and
viewing conditions.
