Background: P300 Speller systems conventionally are using an oddball pattern which results in P300 component. By using the P300 component, mentally disabled can spell different characters.One of the most disadvantages of ERP-based BCI systems, especially P300 spellers, is the need for a large amount of training data which is time-consuming and exhausting for users.
New method: The goals are to evaluate the possibility of Transfer Learning (TL) implementation using the finetuning technique on convolutional neural networks (CNN) by two different approaches: 1) Cross-Subject, and 2) Cross-Paradigm. In cross-subject, data of individual paradigm cross different subjects and in cross-paradigm, data of individual subject cross different paradigms were applied.
Results: The final results illustrate that the amount of network training data is reduced up to 75 percent. Furthermore, the average of character detection accuracy using CNN is increased 11.76%, 13.95% and 13.51% in cross-subject TL in comparison to LDA classifier for single, dual and triple paradigms respectively. Also, such accuracy is increased by 6.76%, 10.95% in cross-paradigm TL in comparison to LDA classifier for dual and triple paradigms respectively.
Comparison with existing methods: Cross-subject and the novel cross-paradigm suggested in this study reduce the amount of needed training data in comparison to existing subject-dependent methods. In addition, the performance overall was improved against LDA in TL condition.
Conclusions: Overall in cross-subject and cross-paradigm TL approach using CNN, character detection accuracy was improved in comparison to LDA and the amount of training data was decreased significantly.
Amir Mohammad Mijani, Aref Einizade, Mohammad Bagher Shamsollahi and Behrad Taghi Beyglou