Xavier Perrin Ricardo Chavarriaga Céline Ray Roland Siegwart José del R. Millán A comparative psychophysical and EEG study of different feedback modalities for HRI. 41-48 2008 HRI http://doi.acm.org/10.1145/1349822.1349829 conf/hri/2008 db/conf/hri/hri2008.html#PerrinCRSM08