bci2000.org BBS

Dear all,
we are the Italian group that attended the BCI2000 workshop in Utrecht. As usual, we have a question for you: we would like to see how amplitudes of the P300 response changed during our task (i.e. not in the calibration phase, but in the free-spelling one). Could you please give us all the information needed to do this analysis (loading the files, status code and stimulus code..)? Because, mantaining the same parameters of the Calibration phase, we got an error message.

Than you so much,

best wishes

Joanna, Gigi and Marcello

Hi all,

in free-spelling mode, the subject decides by his/herself which letter to spell. Thus, no information is available in the data to determine whether a given stimulus was attended or not. As a consequence, it is not possible to do such an analysis unless you manually supply the information contained in the StimulusType state.

You can do this by using the load_bcidat mex file to load the data into Matlab, then set StimulusType to 1 whenever a row or column was flashed that contained the attended letter. Then, use the save_bcidat mex file to save the modified data as a BCI2000 data file.

Best regards,
Juergen