[Eeglablist] ICs with identical topographies

[Maximilien Chaumon]

Hi eeglabbers,

I sometimes get ICs with extremely similar topographies and time courses,
like on this slide <http://oszilla.hgs.hu-berlin.de/public/Similar_ICs.PNG>.
I know that ICA returns independent components.
Does that not mean that they should not look the same?
I know the components are independent in a statistical sense, which is not
the same as uncorrelated, but still. I'm a bit surprised. What do these two
components mean if they cancel one another? well, do they?

Sorry if my question is naive, but what is happening?

The data is here <http://oszilla.hgs.hu-berlin.de/public/Similar_ICs.mat>.

Best,
Max
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