Information-Theoretic Analysis of Refractory Effects in the P300 Speller

The P300 speller is a brain-computer interface that enables people with neuromuscular disorders to communicate based on eliciting event-related potentials (ERP) in electroencephalography (EEG) measurements. One challenge to reliable communication is the presence of refractory effects in the P300 ERP that induces temporal dependence in the user's EEG responses. We propose a model for the P300 speller as a communication channel with memory. By studying the maximum information rate on this channel, we gain insight into the fundamental constraints imposed by refractory effects. We construct codebooks based on the optimal input distribution, and compare them to existing codebooks in literature.