SSVEP-based BCI control of the DASHER writing system

Steady state visual evoked potentials represent the least training-dependent brain computer interface paradigm, a condition that significantly improves the user experience with this kind of interfaces. On the other hand, the open-source DASHER writing system is an unconventional machine interface paradigm on its own, for which their developers encourage the search of new controlling mechanisms. In this paper, we report the use of a single steady-state visual stimulus approach to control the navigation vector of the DASHER writing system. Fourier-based power estimation was used to compute the power around the fundamental band of the evoked response detected in occipital electrodes, and user-dependent threshold was used as the directional control. In an online trial, a short word was successfully -albeit inefficiently- written by a naive user, which suggests the feasibility of the application of such a paradigm for performing this task.