Trouble with nested matrices

Known Issues and Problems with BCI2000
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stefan
Posts: 13
Joined: 22 Oct 2009, 16:43

Trouble with nested matrices

Post by stefan » 22 Oct 2009, 16:54

I just found out that I am not able to select sub menus in nested matrices unless I check the "display results of copy/free spelling" option, otherwise it ignores my selection and stays with the current menu. Can someone confirm that this is the normal and intended behavior?

Stefan

mellinger
Posts: 1065
Joined: 12 Feb 2003, 11:06

Post by mellinger » 23 Oct 2009, 10:10

Stefan,

what you describe is intended behavior of the P3Speller.Typically, you perform one or more P3 spelling sessions in copy mode, in order to obtain training data for the P3 classifier. At first, you don't have valid classifier weights, such that classification results are nearly random. To avoid confusing the subject, you want to suppress classification results by setting the DisplayResults parameter to "off". If later on you have valid weights in a copy spelling session, you may switch DisplayResults to "on", which will enable text output and switching of submatrices at the same time.

If you would like to change this behavior, I can assist you in making the appropriate changes to the P3Speller source code (putting additional elseif clauses into P3SpellerTask.cpp after line 672).

Regards,
Juergen

stefan
Posts: 13
Joined: 22 Oct 2009, 16:43

Post by stefan » 23 Oct 2009, 11:27

Juergen,

Your explanation makes sense but I am wondering if it wouldn't be better to make the functioning of sub-matrices dependent on the InterpretMode instead of the DisplayResults option, e.g., disable it in copy mode but enable it in online free mode. This seems a little more intuitive to me. What do you think?

Thanks,
Stefan

Edit: The reason I am asking about this is that we have scenarios where we want to feed the speller output to an external application, like BCIKeyboard or other environmental control systems, and the user does not necessary want to see the selection results on the speller window (they could be arbitrary control character sequences), so we would typically turn off the DisplayResults option in online free mode to avoid confusion.

mellinger
Posts: 1065
Joined: 12 Feb 2003, 11:06

Post by mellinger » 27 Oct 2009, 09:43

Stefan,

if we would modify the P3Speller application according to your suggestion then someone would want to use sub-matrices in copy spelling mode, and wouldn't be able to.

One of the reasons why BCI2000 provides access to its source code is to enable users to make their own modifications, and adapt it to their special needs. I can assist you in making the necessary modifications if you wish.

Regards,
Juergen

stefan
Posts: 13
Joined: 22 Oct 2009, 16:43

Post by stefan » 03 Nov 2009, 09:44

Juergen,

Thanks for offering your assistance. I noticed we can work around this by always turning on DisplayResults but changing StatusBarSize and StatusBarTextHeight to 0 so we should be ok.

Stefan

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