The Neurophysiological Biomarker Toolbox (NBT)



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Running a spelling session

In the spelling session, the subject does what he/she did in the calibration session, only this time you will first load the P300Classifier parameter file you saved. The real spelling can begin!

Spelling session

  1. When you have saved a parameter file in P300Classifier, it is time to start BCI2000 again. If you have not started a new session in Net Station, do that first.
  2. Load the parameter file “BCI2000 parameters freespelling.prm” file.
  3. Also load the parameter file you saved with P300Classifier, which contains the feature weights (i.e., the one saved in the subject's folder, e.g., MAM16.S0009001\MUDChS1_CAR_SW). Only the feature weights will be loaded from this file and so you will now be running a session with the same parameters as the calibration session, except that the letter classifier will now use these new feature weights.
  4. Change the run number in the Storage tab, so that you do not overwrite your previous files. Thus, change ”#epochs to average” in “filter” tab and change ”#sequences” in “application” tab.
  5. [This step is not needed if a proper “BCI2000 parameters freespelling.prm” file has been loaded]. If you would like to run a “free spelling” session where you do not have to copy the word on the screen, go to the application tab and find the Interpret Mode dropdown menu in the Result Processing section. Select “online free mode” and you will now be able to spell any message that you would like.
  6. Save the parameter file and overwrite the “BCI2000 parameters freespelling.prm” file, so you don't have to load the P300Classifier parameters if you want to use the same parameters in the future. To make sure you use the correct parameters for the free spelling, you can also save the “BCI2000 parameters freespelling.prm” with a subject extension.
  7. Click Set Config to load the spelling task.
  8. Ask your subject if he/she is ready, and if so, click Start. Do not forget to click the background to get rid of the windows in front of it. Also remember to switch subject screen to the PC output.

This is the end of the tutorial for conduction a P300 speller experiment. You can return to the main menu or proceed to Plotting ERPs in EEGLAB.

courses/running_a_spelling_session.txt · Last modified: 2016/01/20 17:05 by Klaus Linkenkaer-Hansen
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