[Eeglablist] Problem with epoching and boundary events

Philipp Spachtholz Spachtholz at psy.lmu.de
Fri Jan 10 03:20:02 PST 2014

Dear all,

i am new to EEGLAB and started doing some scripting and came across a 
problem. Maybe
someone can help me.

I import data from Brain Vision Analyzer (where i marked bad data 
stretches). I then read out the
datapoints of these bad strechtes using the event "userdefined" and 
subject those values to
eeg_eegrej. This seems to work well and the bad stretches are replaced 
with a boundary event.

However when I do epoching over all stimulus events (each stimulus event 
only occurs once in my experiment), some of them are epoched although 
the interval contains a boundary event.
For example i have a Stimulus type 'S 79' which is followed by a 
boundary event within 1 second. If i specifically select this event for 
epoching with a time range of [-0.6 1.8] i get an error (which makes 
sense to me).
If i select stimulus type 'S 79' and the succeding event after the 
boundary event (or another one), only the event
after the boundary is selected for epoching --> I get 1 epoch.

However when i select more than 2 stimulus types for epoching, e.g. 3 
events then I get 3 epochs,
including the S 79.

Do you have any idea why this might happen?
This happens both using the script and the gui.

thank you very much for your help

Philipp Spachtholz

Dipl. Psych. Philipp Spachtholz

Department of Psychology
University of Munich
Leopoldstrasse 13
80802 Germany
Phone: +49 (89) 2180-5229
E-Mail: Spachtholz at psy.lmu.de

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