The effect of monitor raster latency on VEPs, ERPs and Brain–Computer Interface performance

Publication date: 1 February 2018
Source:Journal of Neuroscience Methods, Volume 295
Author(s): Sebastian Nagel, Werner Dreher, Wolfgang Rosenstiel, Martin Spüler
BackgroundVisual neuroscience experiments and Brain–Computer Interface (BCI) control often require strict timings in a millisecond scale. As most experiments are performed using a personal computer (PC), the latencies that are introduced by the setup should be taken into account and be corrected. As a standard computer monitor uses a rastering to update each line of the image sequentially, this causes a monitor raster latency which depends on the position, on the monitor and the refresh rate.New methodWe technically measured the raster latencies of different monitors and present the effects on visual evoked potentials (VEPs) and error-related potentials (ERPs). Additionally we present a method for correcting the monitor raster latency and analyzed the performance difference of a code-modulated VEP BCI speller by correcting the latency.Comparison with existing methodsThere are currently no other methods validating the effects of monitor raster latency on VEPs and ERPs.ResultsThe timings of VEPs and ERPs are directly affected by the raster latency. Furthermore, correcting the raster latency resulted in a significant reduction of the target prediction error from 7.98% to 4.61% and also in a more reliable classification of targets by significantly increasing the distance between the most probable and the second most probable target by 18.23%.ConclusionsThe monitor raster latency affects the timings of VEPs and ERPs, and correcting resulted in a significant error reduction of 42.23%. It is recommend to correct the raster latency for an increased BCI performance and methodical correctness.



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