Hi everybody,
I would like to implement a simple P300 for an application. However, I need an idle state, i.e. the subject will not look at the screen and therefore no P300 will appear. As far as I am a beginner, I do not know how to implement such behavior. Is it possible to use the class rejection of the voting classifier to achieve this ? How ?
Best regards,
duvi
P300 with idle state
Re: P300 with idle state
Hello,
This indeed a difficult, but interesting problem in BCI. I have no experience with that myself. However, based on what I know of the P300 paradigm, I would try the following:
Modify the inputs of the voting classifier to that of type "Stimulations".
Put the checkbox "choose one if ex-aequo" off.
If the user then looks away from the stimulation screen I would expect none of the columns or rows would be classified as a target and thus all inputs to the voting classifier would be zero. Based on the fact it won't choose one in case of ex-aequo it should send the reject label instead. The reject label can also be defined in the configuration window of the voting classifier box.
In the above case, I would personally use a lot of averages and only one repitition in the voting classifier. Because otherwise (if you use more votes and average less) the probability of missclassifying one column or row as target increases.
Not sure if this is the right way, but that's what I would try first.
Best regards,
Dieter
This indeed a difficult, but interesting problem in BCI. I have no experience with that myself. However, based on what I know of the P300 paradigm, I would try the following:
Modify the inputs of the voting classifier to that of type "Stimulations".
Put the checkbox "choose one if ex-aequo" off.
If the user then looks away from the stimulation screen I would expect none of the columns or rows would be classified as a target and thus all inputs to the voting classifier would be zero. Based on the fact it won't choose one in case of ex-aequo it should send the reject label instead. The reject label can also be defined in the configuration window of the voting classifier box.
In the above case, I would personally use a lot of averages and only one repitition in the voting classifier. Because otherwise (if you use more votes and average less) the probability of missclassifying one column or row as target increases.
Not sure if this is the right way, but that's what I would try first.
Best regards,
Dieter
-
fabien.lotte
- Posts: 112
- Joined: Sun Mar 14, 2010 12:58 pm
Re: P300 with idle state
Hi Duvi,
In addition to the nice suggestion of Dieter, you may also have a look into the following publications specifically dedicated to the problem you mentioned:
Haihong Zhang, Cuntai Guan, Chuanchu Wang, "Towards Asynchronous P300-based Brain-computer Interfaces: A Computational Approach with Statistical Models”, IEEE Transactions on Biomedical Engineering, Vol. 55, No. 6, June 2008, pp 1754-1763
(pdf here: http://nsp.i2r.a-star.edu.sg/images/doc ... uanchu.pdf)
F. Aloise, F. Schettini, L. Quitadamo, L. Bianchi, F. Babiloni, D. Mattia, F. Cincotti, "Asynchronous Control in a P300 Task for Domotic Control",
4th International BCI meeting, 2010
(poster here: http://www.tobi-project.org/sites/defau ... CI2010.pdf)
these approach are not implemented in OpenViBE, but if you feel like doing it, you're most welcome
Regards,
Fabien
In addition to the nice suggestion of Dieter, you may also have a look into the following publications specifically dedicated to the problem you mentioned:
Haihong Zhang, Cuntai Guan, Chuanchu Wang, "Towards Asynchronous P300-based Brain-computer Interfaces: A Computational Approach with Statistical Models”, IEEE Transactions on Biomedical Engineering, Vol. 55, No. 6, June 2008, pp 1754-1763
(pdf here: http://nsp.i2r.a-star.edu.sg/images/doc ... uanchu.pdf)
F. Aloise, F. Schettini, L. Quitadamo, L. Bianchi, F. Babiloni, D. Mattia, F. Cincotti, "Asynchronous Control in a P300 Task for Domotic Control",
4th International BCI meeting, 2010
(poster here: http://www.tobi-project.org/sites/defau ... CI2010.pdf)
these approach are not implemented in OpenViBE, but if you feel like doing it, you're most welcome
Regards,
Fabien
Re: P300 with idle state
Thank you !
I will look first the simplest approach and then, try to integrate a more complex one
Best regards,
Duvi
I will look first the simplest approach and then, try to integrate a more complex one
Best regards,
Duvi