[Eeglablist] ICA - very dark activity

[Stephen Politzer-Ahles]

Hi Veerle,

The first component indeed looks like it could be due, at least in part, to
an electrode that was bad during part of the experiment. It is strange
that, for both of these components, the activation reverses over the course
of the experiment (as you can see in the Time*Trials plot in the upper
right). And they have weird activity in the higher frequencies, which might
be artifactual.

But on the other hand, since these components have such high numbers (68
and 26), it is possible that they are not contributing to much of the
variance in your data. If my understanding is correct, the components are
sorted in order from the ones that account for the most variability in the
data (IC #1) to the least. Maybe someone else on the list who has more
experience with components might have a better idea what these components
might be.

Best,
Steve

Stephen Politzer-Ahles
New York University, Abu Dhabi
Psychology Department
http://files.nyu.edu/spa268/public


On Wed, Jul 31, 2013 at 4:25 AM, Veerle Ross <veerle.ross at uhasselt.be>wrote:

> Hi all
> While performing ICA on my data I came across 2 components that show very
> dark activity (the images are available via the links below). Does anyone
> know what this means? Problems with electrodes?
> Best regards
>
> http://wikisend.com/download/480014/ICA_activity.png
> http://wikisend.com/download/386940/ICA_activity2.png
>
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