This app implements the classical P300 speller based on the the row-column paradigm (RCP) proposed by Farwell and Donchin.
The RCP displays a matrix of commands whose rows and columns are highlighted in a random order. For each selection (i.e., trial), the user has to stare at the target command while ignoring the other stimuli. When the trial ends, the application finds out the command by detecting the P300 elicited in the EEG of the user just after each target stimulus.
The original purpose of the RCP speller was to improve the independence and quality of life of severely disabled people by providing a new channel of communication between the brain and the environment . Although this paradigm has been surpassed in recent years in terms of precision and selection speed by more advanced options, such as SSVEPs and c-VEPs, it is still widely used and it can be applied to investigate attention, visual information processing and cognitive responses within the brain.
The RCP speller app for MEDUSA© Platform provides advanced options. First, it allows to configure all the important parameters: stimulus duration, inter-stimulus interval, text or icon commands, flashing colors or command functions. Moreover, the available models for P300 detection include widely used options, such as rLDA, or advanced deep convolutional neural networks, such as EEGNet or EEG-Inception to improve performance . It is also worth mentioning that it allows to include nested matrices to design complex real-life applications. The current implementation has been used in several studies to date, delivering state-of-the-art results [1, 2, 3, 4].
Visit the forum entry of this app at https://forum.medusabci.com/d/5-rcp-speller-issues to report issues and make improvement suggestions!
The following GIF shows the application: