Previous works have reported that complex emotional and visual stimuli can increase the amplitude of the P300 brain potential. Thus, the aim of the present work is to assess these kinds of images in a P300 brain-computer interface speller as flashing stimuli. Twenty-three volunteers controlled four spellers with different sets of flashing stimuli: flashing letters (FL), neutral pictures (NP), emotional pleasant pictures (EPP) and emotional unpleasant pictures (EUP). The sets of pictures showed a higher performance than the letters in accuracy and information transfer rate. These results were supported by the analysis of the P300 signal, where the picture sets offered the greatest amplitudes. The NP and EPP sets were the best evaluated in the subjective questionnaire. In short, despite the fact that the effect of emotional stimuli could not be observed in the performance metrics, picture sets have offered a high performance and should be considered in future proposals.
