Improving user experience of SSVEP-BCI through reduction of stimuli amplitude depth

International audience; Steady-States Visually Evoked Potentials (SSVEP) is currently one of the most widely used paradigms in Brain-Computer Interfaces (BCI). Although the SSVEP-BCI are characterized by their high and robust classification performance, the repetitive presentation of flickering stimuli is uncomfortable from a user experience perspective point of view. Indeed, the low-level visual features of SSVEP stimuli make them straining to the eyes over time and could be disruptive to the execution of tasks requiring sustained attention. They could even induce epileptic seizures. This study explores the reduction of the stimulation amplitude depth (a magnitude diminution of 90%) for the design of SSVEP stimuli as a solution to improve user comfort. The classification accuracy obtained by different pipelines was systematically compared between low amplitude and standard full amplitude SSVEP stimuli. The results reveal high classification accuracy for both high (99.8%) and low magnitude (80.2%) stimuli using the Task-Related Component Analysis (TRCA) classification method. The present findings demonstrate the validity of reducing SSVEP stimuli amplitude to increase users' comfort paving the way for transparent BCI operation.