Integrating dynamic stopping, transfer learning and language models in an adaptive zero-training ERP speller.
OBJECTIVE
Most BCIs have to undergo a calibration session in which data is recorded to train decoders with machine learning. Only recently zero-training methods have become a subject of study. This work proposes a probabilistic framework for BCI applications which exploit event-related potentials (ERPs). For the example of a visual P300 speller we show how the framework harvests the structure suitable to solve the decoding task by (a) transfer learning, (b) unsupervised adaptation, (c) language model and (d) dynamic stopping.


METHODS
A simulation study compares the proposed probabilistic zero framework (using transfer learning and task structure) to a state-of-the-art supervised model on n = 22 subjects. The individual influence of the involved components (a)-(d) are investigated.


RESULTS
Without any need for a calibration session, the probabilistic zero-training framework with inter-subject transfer learning shows excellent performance--competitive to a state-of-the-art supervised method using calibration. Its decoding quality is carried mainly by the effect of transfer learning in combination with continuous unsupervised adaptation.


CONCLUSIONS
A high-performing zero-training BCI is within reach for one of the most popular BCI paradigms: ERP spelling. Recording calibration data for a supervised BCI would require valuable time which is lost for spelling. The time spent on calibration would allow a novel user to spell 29 symbols with our unsupervised approach. It could be of use for various clinical and non-clinical ERP-applications of BCI.
Electronics and Information Systems (ELIS) Department, Ghent University, Sint Pietersnieuwstraat 41, B-9000 Ghent, Belgium.
Pieter-Jan
PJ
Kindermans
Michael
M
Tangermann
Klaus-Robert
KR
Müller
Benjamin
B
Schrauwen
D000465:Algorithms; D001185:Artificial Intelligence; D001931:Brain Mapping / Q000379:methods; D062207:Brain-Computer Interfaces; D003143:Communication Devices for People with Disabilities; D003198:Computer Simulation; D004569:Electroencephalography / Q000379:methods*; D005071:Evoked Potentials / Q000502:physiology*; D006801:Humans; D007802:Language; D008328:Man-Machine Systems; D008962:Models, Theoretical; D018511:Systems Integration; D014584:User-Computer Interface