[Eeglablist] Importing events from Netstation

[Stephen Politzer-Ahles]

Hi Stephen,

I haven't used ERPlab so I'm not sure about the problem with that (and I
assume getting this to work in ERPlab will be more straightforward than the
solution I'm about to describe). If you have the accuracy information for
each subject in a format that's readable by MATLAB, you can use it to
iterate through EEG.event (or EEG.epoch) in EEGLAB and rewrite the events
based on the accuracy. For example, if your events are coded with integers
from 1-9, you could append a 0 on the codes for the incorrect ones and a 1
on the codes for correct ones (so a correct response in condition 1 would
be coded 11, and an incorrect response 10). I don't know the exact format
of your data, but it would involve something like this for each subject

% first load the accuracy data (using importdata(), dlmread() or similar
function)

% go through each trial
for i=1:length(EEG.epoch)
% append the accuracy code to the event code
% accuracy is a vector whose length is the number of trials, each element
indicates whether that trial was responded to correctly
EEG.epoch(i).eventtype = [EEG.epoch(i).eventtype accuracy(i)];
end;

Then once the events are rewritten, you can extract sets of epochs using
the new codes (e.g., extracting only the correct trials for condition 1,
etc.)

Best,
Steve


On Thu, Sep 20, 2012 at 8:14 PM, Stephen Hamilton <sthamilton at ucdavis.edu>wrote:

> Dear all,
>
> This is probably a very simple question with a straightforward answer, but
> I can't find it mentioned in previous posts. Apologies if I've missed it.
>
> I'm importing data recorded in Netstation (128 channel EGI system) into
> EEGlab so that I can reject artifacts using ICA. With Netstation, events
> are written into the .RAW files themselves, so I'm able to segment the data
> by condition very easily. However, I'm unable to distinguish correct trials
> from incorrect trials. When I try to import the event file given by
> Netstation, EEGlab doesn't like the fact that it's in string
> format. So, I've tried assigning events manually using the eventlist GUI
> provided by the ERPlab toolbox, but I'm unable to get it to read the
> accuracy information. This is, I think, because EGI/Netstation evaluates
> trial accuracy with TRSP events at the end of each trial and these
> evaluations are not tied to the condition labels themselves. If I open the
> Netstation event file the TRSP evaluation ("eval1" or "eval0") is provided
> at the end of the line for that event,  I just can't get EEGlab to read
> it. It's probably just a matter of tying these together in the Binlister
> somehow, but I can't find an example of how this is done.
>
> Again, sorry if this has been answered before. Any help would be much
> appreciated!
>
> S Hamilton
>
>
> --
> Dr. Stephen Hamilton
> Postdoctoral Researcher
> Language Processing Lab
> University of California, Davis
>
>
>
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-- 
Stephen Politzer-Ahles
University of Kansas
Linguistics Department
http://people.ku.edu/~sjpa/
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