[Eeglablist] epoch length inquiry for short trials

[Scott Makeig]

Brian -

There is no problem with extracting overlapping epochs if you keep in mind
which parts overlap.  If you are interested in measures in the
time/frequency domain (ERSP, ITC, coherence and cross-coherence, etc.),
then it is necessary to use a long enough trial epoch to include, e.g., at
least one time window wholly within the trial 'baseline' period before the
first latency of analysis interest (to enable within-trial
before/during/after comparisons), and at least one window centered at the
last latency of analysis interest. To measure down to 3 Hz - using a
3-cycle window to improve spectral resolution - a -1-s to 2-s window length
is sufficient.

Scott Makeig

On Sun, Jan 2, 2022 at 11:55 PM Kavanaugh, Brian via eeglablist <
eeglablist at sccn.ucsd.edu> wrote:

> Hi everyone,
>
> Our kids go/nogo task has shorter trials (500 ms stimuli, 900 ms response
> window [or until response], 200 ms inter-trial interval) than the -1 to 2
> second epoch time length. Particularly as we are interested in midline
> theta activity.
>
> I'm sure this has been explained before, but I struggled to find it in the
> archives. I apologize in advance.
>
> If I use the -1 to 2 sec epoch in eeglab, won't these epochs overlap
> trials? Making inter-trial intervals longer would seem to solve this issue,
> but now that data has been collected... Any advice on optimal epoching?
>
> Thank you!!!
>
> Brian
>
>
> Brian Kavanaugh, Psy.D., ABPP
>
> Board Certified in Clinical Neuropsychology, Pediatric Subspecialist
>
> Pediatric Neuropsychologist, E. P. Bradley Hospital
>
> Assistant Professor (Research), Warren Alpert Medical School of Brown
> University
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-- 
Scott Makeig, Research Scientist and Director, Swartz Center for
Computational Neuroscience, Institute for Neural Computation, University of
California San Diego, La Jolla CA 92093-0559, http://sccn.ucsd.edu/~scott