[Eeglablist] baseline correction problem

[mirek]

Hi all,

The question seems to be quite basic, but still unresolved for me...

I work (or trying to) using study/designs to compute and plot ERPs. The 
problem is with the baseline. The plotted ERPs are definitely not 
properly baseline corrected, however the prestimuls baseline interval is 
set when precomputing channel measures (i.e.: "[-100 0]", since I need 
-100 to 0 ms correction).

I've checked whether the correction works to find out, that it does, but 
in unpredictable (for me) manner. Depending on the interval I set for 
correction, the ERPs are really moved up and down relative to x axis. 
However, they are still not in the right place...

My ERPs are segmented from -1000 to 2000 ms, artifactual ICs are marked 
as bad and rejected in the stage of precomputing channel measures.

I thought that it has something to do with artifactuals ICs which could 
be removed AFTER baseline is corrected. However it is not the case, 
since there is even more unpredictable offset at the posterior 
electrodes, where artifacts (mostly ocular) are relatively weak.

The same problem is visible for component cluster ERPs and it persists 
with the EEGLAB 10 as well as 11.

Any help...?


-- 
Mirek Wyczesany
Jagiellonian University
Psychophysiology Lab
Kraków, PL


PS. In the code of std_precomp I've found a remark at the 'rmbase' 
parameter: "%deprecated, for backward compatibility purposes, not 
documented"