[Eeglablist] Conducting ICA on correct or all epochs

Tarik S Bel-Bahar tarikbelbahar at gmail.com
Wed Nov 10 23:00:43 PST 2010

Hi Baris, I am not sure, but it might depend on what you want your
artifactual ICA components to reflect, artifacts during correct trials
only, or across the participant's whole performance. With some
individuals, incorrect trials may be more informative for the ICA
approach. You may want to compare the cleaned re-composed data after
artifactual IC removal via both all three possible methods (only
correct trials, only incorrect trials, and all trials), and make a
decision from there. Overall, it is hard to imagine a scenario where
the brain activity during incorrect trials (or perhaps those preceding
correct ones) are completely irrelevant, so in my humble opinion, I
would do the tripartite comparison above, seeing if my statistical
results change based on different cleaning paths. If no difference
amongst the cleaning techniques, then using the "cleaned from only
correct trial artifacts" would be defendable. Cheers, Tarik

On Wed, Nov 10, 2010 at 1:19 PM, Baris Demiral
<demiral.007 at googlemail.com> wrote:
> Hi everyone,
> I am running a simple EEG experiment where I measure reaction times and
> accuracies.
> I want to use ICs for artifact removal, and I will report only the correct
> trials (hits).
> So would it be better to use the correct epochs for the ICA to correct for
> the artifacts or is it OK to use all the epochs to detect the artifacts and
> then run the artifact correction (pop_subcomp) followed by deleting the
> incorrect epochs?
> Thanks,
> Baris
> --
> SB Demiral, PhD.
> Department of Psychology
> 7 George Square
> The University of Edinburgh
> Edinburgh, EH8 9JZ
> UK
> Phone: +44 (0131) 6503063
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