Fig. 4.

Results of the validation of the EEG-based orientation search. a–f Subject-wise search results. Optimized orientations from single searches are depicted with red and blue markers. Mean curves of the optimized P20–N40 amplitudes constructed from the data measured in Experiment 1 are visualized with solid black lines, and the vertical dashed lines illustrate the maxima of the mean curves (ground-truth optimal orientations). Shaded grey areas indicate the standard deviation of the single-trial P20–N40 amplitudes. Subjects of Group A are presented in a–c and subjects of Group B in d–f. g Convergence of the automated orientation searches. Red (Group A) and blue (Group B) lines depict the convergences of the single search runs, and the black curve represents the average error until the minimal number of samples (30) is reached. The end results are presented with red and blue markers. The horizontal dotted line marks an error of 25°. h Average error in the search results as a function of the signal-to-noise ratio. i Average number of samples needed as a function of the signal-to-noise ratio. The marker shapes and colours in g–i corresponds the subject-wise marker styles in a–f. (For interpretation of the references to colour in this figure legend, the reader is referred to the Web version of this article.)