[Eeglablist] synchronizing eye tracking and EEG data

[keskinmer at itu.edu.tr]

Dear all,

I use EYEEEG plugin of EEGLAB and am having troubles when synchronizing eye
tracking (ET) and EEG data.

Before I synchronize the ET data with the EEG recording through shared
events, I first filter the raw ET data outside EEGLAB (with a script to
remove saccades whose size is >20 deg and also remove the corresponding
preceding saccade. The script also filters out the fixation durations other
than 50-1000ms long, as well as the corresponding following fixation).

I use this filtered ET file for syncronization and here is what EEGLAB
returns for synchronization quality:

/Warning: For 8 of 11 EEG events (72.7%), no ET event of same name was
found within plusminus 5 samples. Possibly, some events were not
transmitted to the eye tracker?Synch. error is the latency difference
between matching ET/EEG events after synchronization./

I tried it with several data. When I check synchronization plots, EEG and
ET events sometimes aligned and sometimes not, but the mode of distribution
is never 0 (quality of synch graph).

Is it because ET data is not continuous anymore because I took out some
saccade and fixations? I tried to look for an answer online, but I couldn't
find anything helpful. Can anyone help me where I can be wrong?

All the best,
Merve
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://sccn.ucsd.edu/pipermail/eeglablist/attachments/20180104/824cc639/attachment.html>