[Eeglablist] A question about the averaging for the P300 Speller

[Ettore Coppola]

Sorry for my bad English!
A question about the averaging for a P300 work.
The P300 Speller has  a 6 x 6 matrix of characters. Each row and each column are intensified by the system; the intensifications are presented in a random sequence.
The user focuses attention on one of the 36 cells of the matrix, with the row and the column containing the character to be communicated constituting the rare set (target) , and the other 10 intensifications constituting the frequent set (no-target).
In a first phase we go to train the classificator: in this phase the system knows if every epoch is  target or  no-target.
In the online phase, when the user tries to select a character, the system doesn’t know if an epoch is target or no-target.
In this situation, the  online phase, is useful to average epochs? In the average, we’ll have together target and no-target epochs : I think that the the P300 elicited  in the  target epoch will be  very low for the average with the no target.
Am I right?
Ettore


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