Changing P3Speller parameters on the fly

[omidsani]

Hi there,

I've been working with BCI2000 and the P3Speller application for a couple of months now and I have been able to implement my own P300 classifier with a fairly good accuracy in Matlab and using FieldTrip as the bridge between BCI2000 and MATLAB.

Now I'm trying to improve the speed of my speller and one thing I would like to do is changing some parameters according to the current level of confidence of my classifier on the fly. For example I would like to decrease the NumberOfSequences parameter of the P3Speller App if my classifier is currently very confident on its decisions and do the opposite if I'm getting chance level decisions from it. At the beginning of an online session the NumberOfSequences parameter might be 15 and after some time it might change to 10 and then maybe to 12 and so on... Moreover, I might also want to change other parameters such as StimulusDuration on the fly.

Is this possible without building the P3Speller app from the code? Is changing parameters (not states) on the fly possible at all in BCI2000. I have seen videos of groups who have implemented such adaptive P300 Spellers using BCPy2000 and I'm sure it is possible. But do I have to modify the P3Speller app's code and build it to accomplish such a thing?

Thanks

[mellinger]

Hi,

BCI2000 parameters generally represent user choices, and cannot be changed dynamically during operation.

However, you will not need to write your own code for dynamic adaptation of the number of sequences, as such a feature is already implemented in the P3Speller and other stimulus-oriented tasks in BCI2000.
It is available in the latest version of the BCI2000 source code, and documented here:
http://www.bci2000.org/wiki/index.php/U ... umEvidence

In order for it to work properly with your own classifier, make sure to also read these notes:
http://www.bci2000.org/wiki/index.php/P ... imulusTask

Regards,
Juergen