ERPs but different length of recording for different stimuli. How to compare?

hollyholly United Kingdom
in Research
Hello,

 want to compare between recordings  (ERPs for different stimuli). The issue is, that the recordings I have received (I am analysing another researcher's dataset) fluctuate between 10 - 12 seconds of length for different stimuli. How does one go about comparing stimuli when they are different lengths like this? (In the original paper each trial is supposed to be 10 seconds). Are there some preprocessing steps I am missing? Or is this a fault with the data?

I am an EEG novice so any help would be really appreciated! 

Thanks,

Holly

Comments

  • wjcroftwjcroft Mount Shasta, CA
    Holly, hi.

    In EEG trials, a recording or segment usually encompasses both before and after the stimulus. Thus you need to know the exact time point when the stimulus is applied within the segment. This is generally done with another EEG channel or auxiliary channel, called a 'trigger' or external trigger channel. Check with the authors and ask (for each different stimuli), what position in the segment was the stimuli applied.

    With OpenBCI there are ways to record the external trigger signal along with the EEG channels. Thus achieve exact location in the EEG record when the stimuli was presented.

    Regards,

    William

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