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PostPosted: Mon Mar 23, 2015 12:13 pm 
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Joined: Thu Mar 19, 2015 12:40 pm
Posts: 1
Hi,

I am performing research assessing the Emotiv Epoc's usability in a lightweight P300 application.

I am using OpenViBE for data acquistion together with a modified version of the P300 Speller, with a 3x3 matrix.

The data is to be analysed and used in external programs, both MATLAB where I am using EEGLAB together with my own code as well as in a custom-made python application.

My question is how you would go about to handle the stimuli data in an easy manner to correlate events with the data. I see two alternatives:

1/ Predefine a specific pattern of blinks. As I understand it you have done this and save it in the .ov file in your example. How can I create my own pattern with my own configuration?

2/ Save the data together with the stimuli and import in the other programs. For this I have used the EDF File Writer. I am having a little problem understanding this format and all I would like is a timestamp of which column/row has blinked at what time. Using EDFbrowser I am able to import these events in the annotations. Although, it seems like OpenViBE only saves part of all the events, since I only get a subset of all the occured events. Is there some setting/buffer I am missing or any other way to save the stimulations into a simple .txt-file?

To further clarify what I am looking for I first programmed a P300 Speller interface in Python (3x3) acquired data with the Emotiv SDK and saved the stimulations in one vector in a .txt-file with predefined times between blinks. Example:

10
11
12
20
11
21
22
...

Where 10-12 is rows and 20-22 are columns. I would like to have the same information using OpenViBE since I trust its data acqusition more and see potential in the .edf format.

Thankful for any tips,
Martin Kaalhus


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PostPosted: Tue Mar 24, 2015 12:44 pm 
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Joined: Sun Mar 14, 2010 12:58 pm
Posts: 108
Hello,

Typically, to record events in your P300 speller, you can use the openvibe stimulations, and save them together with EEG signals as GDF format (using the GDF writer box), which can be opened in Matlab using EEGLab or Biosig. I have not tried with the P300 speller, but for Motor Imagery scenarios it works perfectly fine and no stimulations are missing. Have you tried this option?

Let us know,

Best regards,
Fabien Lotte


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