[Eeglablist] ICA Misinformation

Arnaud Delorme arno at ucsd.edu
Wed Jun 14 13:40:38 PDT 2017

Dear Robert,

There does seem to be a phase difference in your powerpoint. However, it is important to know which ICA component you removed to understand why this is the case. Are you sure these were artifactual components? Removing brain components may alter the phase of the signal recorded on the scalp (it would be as if you were removing from the scalp signal the contribution of a brain area). Without that information, it is not possible to figure out the origin of the phase difference. 

This seems to be the same data you shared yesterday. I have looked at it. Black is before ICA and red after removing the 2 eye components. You can see that there is no phase shift at 102.43 second after I remove the two artifactual ICA components. I have provided the code in my email yesterday if you want to reproduce this result in EEGLAB.

Best wishes,


> On Jun 14, 2017, at 11:14 AM, Robert Thatcher <rwthatcher2 at yahoo.com> wrote:
> <Example of Phase Differences at   1min & 46 seconds.pptx>

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