Preliminary Results Using a P300 Brain-Computer Interface Speller: A Possible Interaction Effect Between Presentation Paradigm and Set of Stimuli

Abstract

Several proposals to improve the performance controlling a P300based BCI speller have been studied using the standard row-column presentation (RCP) paradigm. However, this paradigm could not be suitable for those patients with lack of gaze control. To solve that, the rapid serial visual presentation (RSVP) paradigm, which presents the stimuli located in the same position, has been proposed in previous studies. Thus, the aim of the present work is to assess if a stimuli set of pictures that improves the performance in RCP, could also improve the performance in a RSVP paradigm. Six able-bodied participants have controlled four conditions in a calibration task: letters in RCP, pictures in RCP, letters in RSVP and pictures in RSVP. The results showed that pictures in RCP obtained the best accuracy and information transfer rate. The improvement effect given by pictures was greater in the RCP paradigm than in RSVP. Therefore, the improvements reached under RCP may not be directly transferred to the RSVP.

Performance Analysis With Different Types of Visual Stimuli in a BCI-Based Speller Under an RSVP Paradigm

“…Comparing the obtained results with those of previous studies that also assessed RSVP spellers using only letters as stimuli, it can be observed that the reported accuracy and ITR values of this study are similar to those reported in the literature Chennu et al, 2013;Lin et al, 2018;Won et al, 2018;Fernández-Rodríguez et al, 2019c). To the best of our knowledge, the FF condition has not been used before for communication purposes under RSVP, and the NP condition has only been evaluated in a preliminary study (Fernández-Rodríguez et al, 2019c). Thus, the performance achieved by the FF or NP paradigms cannot be fairly compared to any other study, highlighting the novelty of this work.…”

“…Nevertheless, studies regarding the nature of the stimuli under RSVP have barely been carried out for communication purposes (i.e., RSVP spellers). In a preliminary study, neutral images and letters were compared in RSVP (Fernández-Rodríguez et al, 2019c). The results of this work showed that neutral images did not offer significant benefits as compared to letters under the RSVP paradigm.…”

“…The number of elements was selected in order to avoid a target selection time that was too long, as the aim of this study was to validate the different sets of stimuli under RSVP for communication purposes. In previous studies with this kind of paradigm, an even smaller number of elements has been used to validate hypotheses (Chen et al, 2016;Fernández-Rodríguez et al, 2019c).…”

“…In the same way, to our knowledge, any studies regarding RSVP have compared FF to letters and it would be interesting to determine the efficacy of FF under a RSVP paradigm. However, the results of Fernández-Rodríguez et al (2019c) should also be carefully considered as a small sample size was applied and no metrics regarding the user experience were considered (such as fatigue, preference and control). To better understand the effect of this sort of stimuli when applying an RSVP paradigm, an extended and complete study regarding neutral images and FF against letters should be carried out.…”

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“…Nevertheless, studies regarding the nature of the stimuli under RSVP have barely been carried out for communication purposes (i.e., RSVP spellers). In a preliminary study, neutral images and letters were compared in RSVP (Fernández-Rodríguez et al, 2019c). The results of this work showed that neutral images did not offer significant benefits as compared to letters under the RSVP paradigm.…”