[Eeglablist] appropriate baseline for end of long trial?

[Baris Demiral]

Hi Daniel,

One thing you can do is to take the whole trial epoch for base-line as we do
before ICA.
Another thing might be to take the difference between the amplitude of the
1s duration post-response from the 1s duration pre-trial interval, and
subtract the difference form the whole epoch. Or, sum them up and divide
into two. That way you can normalize to the both "ends".

Best,
Baris

On Sat, May 7, 2011 at 12:24 PM, Levy Daniel <daniel.levy at idc.ac.il> wrote:

>  Esteemed colleagues,
>
>
>
> We are running a working memory experiment in which each trial involves a
> number of judgments on a stimulus that is only presented once, such that
> trial length (from a cognitive perspective) is up to 20 sec. Baseline EEG
> preceding the trial does not seem to be appropriate for normalizing EEG
> recorded at the end of the trial. On the other hand, since information is
> being actively maintained in WM during the whole trial period, using
> intermediate epochs such as fixations does not seem proper either. We are
> thinking of using a baseline starting 1 sec after the final response of the
> trial, i.e., the time immediately preceding the beginning of the following
> trial, to normalize the last EEG segment before that final response of the
> preceding trial. Is that problematic?
>
>
>
> Thanks for your advice,
>
>
>
> Daniel Levy
>
> The Interdisciplinary Center
>
> Herzliya, Israel
>
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-- 
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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