[Eeglablist] Epoch Length, and Normalization

[Joseph Nuamah]

Dear Everyone,

I have a data set from an experiment that had two blocks of trials.

Each block had 30 trials. Whereas each trial in block 1 had a duration of
6000ms, each trial in block 2 had a duration of 60 000 ms. The ISI for both
blocks was 3000 ms.

The sampling frequency was 256Hz. A trial ended when a participant clicked
the mouse button. I found out that for both cases, participants clicked the
mouse before elapse of the stipulated trial duration.

My questions are:

1. What epoch lengths do I use for both blocks? Are -500ms to 3000ms, and
-500 to 5000ms okay for block 1 and block 2 respectively?

2. For time-frequency transforms, do I need to subtract the baseline from
the data before I do the transformation?

3. As a follow up from question 2, do I perform ICA before the subtraction?

4. What is the effect of normalizing the data before computing the power in
each channel?

Thanks.

Joseph.
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