Abstract
BackgroundOne of the most common types of brain-computer interfaces (BCIs) is called a P300 BCI, since it relies on the P300 and other event-related potentials (ERPs). In the canonical P300 BCI approach, items on a monitor flash briefly to elicit the necessary ERPs. Very recent work has shown that this approach may yield lower performance than alternate paradigms in which the items do not flash but instead change in other ways, such as moving, changing colour or changing to characters overlaid with faces.Methodology/Principal FindingsThe present study sought to extend this research direction by parametrically comparing different ways to change items in a P300 BCI. Healthy subjects used a P300 BCI across six different conditions. Three conditions were similar to our prior work, providing the first direct comparison of characters flashing, moving, and changing to faces. Three new conditions also explored facial motion and emotional expression. The six conditions were compared across objective measures such as classification accuracy and bit rate as well as subjective measures such as perceived difficulty. In line with recent studies, our results indicated that the character flash condition resulted in the lowest accuracy and bit rate. All four face conditions (mean accuracy >91%) yielded significantly better performance than the flash condition (mean accuracy = 75%).Conclusions/SignificanceObjective results reaffirmed that the face paradigm is superior to the canonical flash approach that has dominated P300 BCIs for over 20 years. The subjective reports indicated that the conditions that yielded better performance were not considered especially burdensome. Therefore, although further work is needed to identify which face paradigm is best, it is clear that the canonical flash approach should be replaced with a face paradigm when aiming at increasing bit rate. However, the face paradigm has to be further explored with practical applications particularly with locked-in patients.
Highlights
Brain-computer interface (BCI) systems allow for communication without movement
P300 BCI ([9], for review, see [10], [11], [12]). This BCI is so named because it relies heavily on the P300, which is a well-known component of the event-related potential (ERP) that is largest when elicited by events that the subject considers important ([13], [14])
Different P300 BCI systems have even been implemented with standard assistive technology (AT) software for text entry, emailing, and internet surfing and evaluated by severely impaired end-users in terms of effectiveness, efficiency satisfaction and other factors ([19], [20], [21])
Summary
Users perform specific mental tasks that each has distinct patterns of brain activity. P300 BCI ([9], for review, see [10], [11], [12]) This BCI is so named because it relies heavily on the P300, which is a well-known component of the event-related potential (ERP) that is largest when elicited by events that the subject considers important ([13], [14]). Different P300 BCI systems have even been implemented with standard assistive technology (AT) software for text entry, emailing, and internet surfing and evaluated by severely impaired end-users in terms of effectiveness (accuracy), efficiency (bit rate and subjective workload) satisfaction and other factors ([19], [20], [21]). One of the most common types of brain-computer interfaces (BCIs) is called a P300 BCI, since it relies on the P300 and other event-related potentials (ERPs). Very recent work has shown that this approach may yield lower performance than alternate paradigms in which the items do not flash but instead change in other ways, such as moving, changing colour or changing to characters overlaid with faces
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