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

Abstract

Brain-Computer Interface (BCI) systems enable an alternative communication channel for severely-motor disabled patients to interact with their environment using no muscular movements. In recent years, the importance of research into non-gaze dependent brain-computer interface paradigms has been increasing, in contrast to the most frequently studied BCI-based speller paradigm (i.e., row-column presentation, RCP). Several visual modifications that have already been validated under the RCP paradigm for communication purposes have not been validated under the most extended non-gaze dependent rapid serial visual presentation (RSVP) paradigm. Thus, in the present study, three different sets of stimuli were assessed under RSVP, with the following communication features: white letters (WL), famous faces (FF), neutral pictures (NP). Eleven healthy subjects participated in this experiment, in which the subjects had to go through a calibration phase, an online phase and, finally, a subjective questionnaire completion phase. The results showed that the FF and NP stimuli promoted better performance in the calibration and online phases, being slightly better in the FF paradigm. Regarding the subjective questionnaires, again both FF and NP were preferred by the participants in contrast to the WL stimuli, but this time the NP stimuli scored slightly higher. These findings suggest that the use of FF and NP for RSVP-based spellers could be beneficial to increase information transfer rate in comparison to the most frequently used letter-based stimuli and could represent a promising communication system for individuals with altered ocular-motor function.

Evaluation of Different Types of Stimuli in an Event-Related Potential-Based Brain–Computer Interface Speller under Rapid Serial Visual Presentation

“…The results of that study were similar to our findings ( Table 3 ). The GFF condition of the present study and the famous face condition of Ron-Angevin et al [ 35 ] stand out in terms of the ITR: they were the only conditions with an accuracy > 90% and an ITR > 17 bit/min.…”

“…It is challenging to contextualise the results obtained in the present study with those from the previous literature due to the use of different paradigms or experimental specifications (e.g., SOA). However, Ron-Angevin et al [ 35 ] used the same configuration to explore the use of three types of stimuli under RSVP: white letters, natural-coloured famous faces without a letter, and pictures without a letter. The results of that study were similar to our findings ( Table 3 ).…”

“…Therefore, our results should be interpreted with caution, and it is advisable that future studies further validate these findings. It is important to remember that other studies conducted using RSVP have shown that the choice of stimulus does not necessarily result in enhanced performance compared with what is achieved in other matrix-based paradigms [ 22 , 35 ]. Hence, it is crucial to consider the specific characteristics of each paradigm to identify the variables that can contribute to enhance performance.…”

Brain-computer interfaces and human factors: the role of language and cultural differences—Still a missing gap?

“…These studies used paradigms with emotional pictures, scenes, music or videos as stimulus input (for an overview, e.g., Garcia-Molina et al, 2013 ; Abiri et al, 2019 ) to induce emotions in the users. Other studies aimed to improve BCI performance, for example during P300-BCI based spelling by additionally using rapid serial visual presentation (RSVP-spellers) with flashing emotional stimuli such as faces ( Ron-Angevin et al, 2021 ). Most recently, datasets comprising hundreds of scenes have been provided to allow pictionary-based communication for the assessment of the physiological needs and motivational states of the user ( Proverbio and Pischedda, 2023 ).…”

Advanced Electrode Technologies for Noninvasive Brain–Computer Interfaces

“…An ideal noninvasive BCI implied great application potential in various fields, including brain science research, communication, − disease diagnosis and treatment, disabled auxiliary, , daily tasks, − emotion detection, − virtual reality technologies, − and military application, etc. By continuously advancing electrode technology through improvements in materials and design, as well as enhancing performance, multifunctional integration, and multimodal collaboration, noninvasive BCI is poised to significantly propel the advancement of intelligent medical systems and could even revolutionize our way of life. − Here, we sketch out the technological roadmap for the development of noninvasive BCI electrode technology from three dimensions: Materials and Design; Performances; Mode and Function (Figure ).…”