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How create events with StimulusCode

Posted: 03 May 2015, 18:08
by Aresuss I
I am a novice in BCI2000 :) and do not understand everything yet, see it - it's my problem to realize (See attachment)

My dataset is retrieved from bci competition III - P300 speller, my job is to load it into EEGLAB and exposure P300 potential when it loads do not know how to create events

I downloaded data from this page: http://www.bbci.de/competition/ii/

In the dataset I do not have a file "events" is only a "stimulus code" and "stimulustype" . I do not know how to make these events to create an epoch's and display the potential of P300

Re: How create events with StimulusCode

Posted: 03 May 2015, 23:11
by boulay
You asked me this question by e-mail and I'm afraid the answer is the same:
This is an EEGLAB question. You have to learn how to use EEGLAB's functions (not the GUI) to create events. You are more likely to get an answer on the EEGLAB mailing list [1]. If this is for a homework assignment, then it's likely someone else has asked the question in the past; try searching its archives.

If you already know how to create events using EEGLAB functions and your question is only "How can I identify target vs non-target stimulus events from the vectors StimulusCode and StimulusType?", then that's probably something that can be answered here. If you were to do a

Code: Select all

plot(StimulusCode); hold on; plot(StimulusType)
then it should become obvious.

Code: Select all

stimCodeIndices = find(StimulusCode~=0 & [0 StimulusCode(1:end-1)]==0); % Indices of when StimulusCode changed from zero to non-zero
stimWasTarget = StimulusType(stimCodeIndices) == 1;  % I can't remember if it's 1 or 2. Please look at the plot to see which StimulusType is rarer.
In the image you've posted, you've only loaded one data file from the competition dataset. If they are all from the same recording session then you'll want to load them all and concatenate them before you insert them into EEGLAB.

Note, for others:
The data files from the BCI competition are in Matlab .mat format. If they were in BCI2000's .dat format then it would be possible to use the BCI2000 extension for EEGLAB to automatically import events.

[1] http://sccn.ucsd.edu/eeglab/eeglabmail.html

Re: How create events with StimulusCode

Posted: 04 May 2015, 02:21
by Aresuss I
Thanks Czad because you helped me a lot, I would like to say something else what they think :)

If .dat format instead of .mat I would not have any problem :)

Re: How create events with StimulusCode

Posted: 04 May 2015, 17:11
by Aresuss I
I've already done , thanks for the help everyone :P