[Eeglablist] EEGLab trouble re-referencing my data to multiple electrodes

[Arnaud Delorme]

Hi Maria,

> By default in Brain Vision Recorder, my reference channel is Fp1.

This means that channel Fp1 should contain 0s.

> However, I have two references, in both earlobes: Fp1 and AF8, and I need
> to reference my data to the mean of these two channels' data.

This is possible in EEGLAB.

> I have checked the procedure in EEGlab Tutorial, where I can create a new
> channel (in Edit --> Channel Locations) in case the original reference does
> not appear visible, as it is the case, in Fp1 for instance. Yet, by
> creating Fp1 as a new channel and set it as my reference (as described in
> Tutorials --> Preprocess Data --> Re-referencing --> Retaining the
> reference channel), the new channel Fp1 does not contain its original data.

Yes, it makes sense that Fp1 would not contain the same data once referenced to Fp1 and AF8. In one case, you have Fp1 referenced to Fp1 (in difference of potential between sensors Fp1 - Fp1) and in the other one Fp1 referenced to the average of Fp1 and AF8 ( Fp1 - (Fp1+AF8)/2).

Arno