[Eeglablist] synchronizing eye tracking and EEG data

[Bernhardsson Jens]

Hi

Besides from what Olaf and Roy have described if you check your warning message you see that the search radius for finding matching events between ET and EEG is set to 5 samples. Try to increase that to RADIUS = 20 in synchronize.m found in the eye-eeg folder. You could increase that value just to check how off the synchronization is. This is also something that you might have to do if you have a high sample rate.

Regards
Jens

Från: eeglablist [mailto:eeglablist-bounces at sccn.ucsd.edu] För keskinmer at itu.edu.tr
Skickat: den 4 januari 2018 11:08
Till: eeglablist at sccn.ucsd.edu
Ämne: [Eeglablist] synchronizing eye tracking and EEG data


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/20180110/1c49fa96/attachment.html>