2013 年 18 巻 1 号 p. 55-62
We measured SSVEP (steady-state visual evoked potential) using contrast-modulated flickers of photographic scenes to apply for AR (augmented reality) system. Ten participants observed the contrast-modulated flickers, which were made of alternating an original image of a photographic scene and its contrast-degraded image (0, 20, 40, 60, and 80% of original contrast) at a rate of 5, 7.5 or 10 Hz. We found that SSVEP was observed even with 80% contrast-image flickers using 1s time-window SFFT analysis. The strength of SSVEP depended on contrast and stimulus frequency. It was stronger with higher contrast and lower frequency. Then, we investigated effects of eccentricity and applied LDA (linear discrimination analysis) to test feasibility of SSVEP-based BMI (brain-machine interface) using the contrast-modulated flickers. We found that gaze could be estimated using 20% contrast-image flickers with LDA of a SSVEP at the stimulus frequency, moreover that it could be estimated using 80% contrast-image flickers with LDA of 20-dimensional data of EEG(1-20Hz). These results suggest that the contrast-modulated flickers of photographic scenes can elicit SSVEP and it could be applied to BMI using AR in a future.