[Eeglablist] Added fields to events, which are suddenly gone

Nils Hachmeister nils.hachmeister at uni-bielefeld.de
Thu Jan 19 01:30:44 PST 2017

Hello everyone,

I have an odd eeglab behaviour, which I don't understand: I added an 
additional field to the events in my data set in order to do some 
additional analyses. This works fine. After adding the field to each 
event in the MATLAB commandline and calling eeglab redraw I can, for 
instance, generate an Channel ERP Image using the gui, sorting trials by 
the new field.

When I want to use this field to select epochs (via the corresponding 
menu), for instance, selecting only those epoch for which the 
time-locking event's new field-value is 0, I get a second data set and 
all the events still have the new field. That's just fine. However, 
going back to the original data set to select all epochs for which the 
new field's value is 2, I notice that the new field is gone for all the 

First I suspected eeglab would do some kind of consistency test, notice 
that the events have a field which is not present in the urevents and 
correct that. That's why in a second attempt I added the new field to 
the urevents (rather than the events) and then copied the new field to 
each event from its corresponding urevent.

Again trying to select a subset of the epochs, the new field is removed 
from the original data set for both, events and urevents. Since I cannot 
see, how this might be sensible behaviour I suspect that I do something 
wrong, due to my limited understanding of the structure spanning between 
event, urevent and epoch.

Can someone help me?!?


Nils Hachmeister

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