P300 Speller xDAWN with Emotiv EPOC

Working with OpenViBE signal processing scenarios and doing scenario/BCI design
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noddy2006
Posts: 2
Joined: Tue Sep 17, 2013 3:55 am

P300 Speller xDAWN with Emotiv EPOC

Post by noddy2006 »

Hi,

I am having trouble getting any results with the Emotiv EEG using the P300 Speller xDAWN scenario. I have tested the scenario on OpenViBE versions 0.15 and 0.16.1, and I am using Emotiv SDK v2.0.0.20 (running on Windows 7 64-bit).

All scenario settings are kept to their default values - the only change I have made has been to change the Drift Tolerance in the Acquisition Server to 6ms. I am able to run the training scenario consistently with a training performance between 77 and 80%. The first time I attempted the scenario, I was also able to achieve 100% accuracy on the online test - however, the 6 or 7 subsequent runs have resulted in 0% online testing performance. I suspect this could be a hardware issue, but I'm not confident that this is the reason due to the reasonably high training performance.

Is there anyone who has used the Emotiv EEG headset successfully with the P300 Speller xDAWN scenario who may be able to assist me in solving my issue? If you require any more information about my set up, please let me know.



Many thanks,

Sam.

jtlindgren
Posts: 775
Joined: Tue Dec 04, 2012 3:53 pm
Location: INRIA Rennes, FRANCE

Re: P300 Speller xDAWN with Emotiv EPOC

Post by jtlindgren »

Hi,

trivial questions first - have you modified all the scenarios to read data from the acquisition server? By default the scenario steps read pre-recorded data from the disk for demonstration / testing purposes. Make sure that all the boxes that read something from the disk, really either read the file that was produced in the previous step, or get their data from the server and not a file. Also, remember to move the scenario folder to a place where you have write access on disk.

If those didn't solve the issue, we'll have to take a closer look.


Best,
Jussi

yrenard
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Re: P300 Speller xDAWN with Emotiv EPOC

Post by yrenard »

Dear Sam,

I see three interesting things you should think of:

1- you should be aware that the P300 wave is best catched on the mid-line between Pz and Fz through Cz. Most setup also include half a dozen of electrodes on the parieto/occipital locations as the visual stimulus gives pretty strong reponses in this brain area. All in all, this is brain areas that are not very well considered by the Emotiv EPOC. If you don't care about accuracy of sensors locations but focus on BCI performance, you might want to turn the headset 180° so that the covering of the parieto/occipital is enhanced.

2- if you are using Windows 7+ (wich you most likely do), disable all the fancy aero effects and Window Composition. This let the OS have better time response in the stimulus presentation, thus reduces lattencies and jittering in the signal tagging. (This should also be considered for SSVEP if you mind)

3- If this is your first attempt at P300 speller, it might also play a role in the issues you are facing. Be patient and try again, some users report betteer performances over sessions.

Well, I hope this helps,
Best regards,
Yann

noddy2006
Posts: 2
Joined: Tue Sep 17, 2013 3:55 am

Re: P300 Speller xDAWN with Emotiv EPOC

Post by noddy2006 »

Hi guys,

Many thanks for your replies.
jtlindgren wrote: ... have you modified all the scenarios to read data from the acquisition server?
Interestingly, when I downloaded the latest version, this was not the case - scenarios 1 and 4 both read using an Acquisition Client, while scenarios 2 and 3 both read from a file (and yes, I am careful to ensure these two boxes read from the correct file each time).
yrenard wrote: ... you might want to turn the headset 180° so that the covering of the parieto/occipital is enhanced.
This was a good idea - I had tried this previously when I was attempting the SSVEP scenarios, but it did not help then. Unfortunately it has not improved the P300 scenarios either.
yrenard wrote: ... disable all the fancy aero effects and Window Composition
Another great idea - especially as the PC I am using is not particularly powerful and occasionally has performance issues - but unfortunately this had no effect either.
yrenard wrote: If this is your first attempt at P300 speller, it might also play a role in the issues you are facing. Be patient and try again...
This is my first attempt at using BCI, but I have been attempting these scenarios (along with the SSVEP scenarios) for several months now. Aside from the first run of the P300 Speller (xDAWN) scenarios which gave me 100% accuracy, I have had no success since.


Thank you for your help so far! :)



Sam.

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