There were three feedback conditions (BCI, sham, and silence) randomly assigned for every new flight attempt. In the BCI condition, subjects heard the sound of a low-rate synthetic heartbeat that was continuously modulated in loudness as a function of the level of inferred task-dependent arousal, as decoded from the EEG. The higher that level of arousal, the louder the feedback and vice versa. Participants' task performance in the BCI condition, measured as time and distance over which the subject can navigate before failure, was increased by around 20 percent. "Simultaneous measurements of pupil dilation and heart rate variability showed that the neurofeedback indeed reduced arousal, causing the subjects to remain calm and fly beyond the point at which they would normally fail," says Josef Faller, the study's lead author and a postdoctoral research scientist in BME. "Our work is the first demonstration of a BCI system that uses online neurofeedback to shift arousal state and improve task performance in accordance with the Yerkes-Dodson law." - www.sciencedaily.com