Comparison of P300 Responses in Auditory, Visual and Audiovisual Spatial Speller BCI Paradigms

TL;DR

This study compares auditory, visual, and audiovisual spatial speller BCIs, finding that auditory responses show promise in training but require further development for practical use with naive users.

Contribution

It provides a comprehensive experimental comparison of three spatial BCI paradigms using naive subjects, highlighting the current limitations of auditory-only approaches.

Findings

Auditory P300 responses show longer latencies during training.

Online multimodal experiments do not confirm the advantage of auditory responses.

Auditory speller paradigms need further development for practical use.

Abstract

The aim of this study is to provide a comprehensive test of three spatial speller settings, for the auditory, visual, and audiovisual paradigms. For rigour, the study is conducted with 16 BCI-na\"ive subjects in an experimental set-up based on five Japanese hiragana characters. Auditory P300 responses give encouragingly longer target vs. non-target latencies during the training phase, however, real-world online BCI experiments in the multimodal setting do not validate this potential advantage. Our case studies indicate that the auditory spatial unimodal paradigm needs further development in order to be a viable alternative to the established visual domain speller applications, as far as BCI-na\"ive subjects are concerned.