The Changing Face of P300 BCIs: A Comparison of Stimulus Changes in a P300 BCI Involving Faces, Emotion, and Movement

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.

An Efficient ERP-Based Brain-Computer Interface Using Random Set Presentation and Face Familiarity

“…This implies that stimuli with higher cognitive task requirements such as facial images, are more effective than the intensified stimuli of dull characters for a P300-based BCI system. As already discussed above, previous studies have shown that faces boost BCI performance [40], [41], [43], [44]. Furthermore, familiar and famous faces have been shown to improve BCI performance even more, when compared to unknown faces [40], [41].…”

A survey of the dummy face and human face stimuli used in BCI paradigm

“…However, only dummy face was used in that study. It was proven that the use of a face pattern was superior to a flash pattern (Jin et al, 2012b). There was no study that showed the difference between dummy faces and human faces that were used in BCI systems.…”

Distinguishing between target and nontarget fixations in a visual search task using fixation-related potentials

“…Because the P300 is relatively easy to detect and its amplitude depends on voluntarily controlled endogenous attentional processes, it is often used as a control signal in brain-computer interfaces (BCIs; Farwell & Donchin, 1988;Jin et al, 2012;Sellers, Krusienski, McFarland, Vaughan, & Wolpaw, 2006). In P300 BCIs, different stimuli are presented sequentially.…”