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Sending EEG triggers on specific frames of movie components

OS : MacOS Catalina
PsychoPy version : 2020.2.10
**Standard Standalone?: yes
What are you trying to achieve?:

Hi, I’m planning to run an experiment with EEG (using BrainVision/ActiCap) and my participants will be watching movie clips. I would like to send triggers on specific movie frames (I have an excel with all the frames and timings that I’m interested in for each clip). I prefer to send them to directly to a frame as I am interested in specific frames so it seems more precise/objective than timings. I’ve found lots of information on how to send triggers via parallel port based on a certain condition (e.g. response), but how do I specify that I want to send the trigger to the particular frames from my conditions file? Can this be done with the builder? Thank you very much in advance!

Hi,

In the parallel port component in builder, you can select ‘frame N’ as the start time to send the trigger and then instead of typing in a number, refer to your excel column variable name that contains the specific frames e.g., $trigger_frames

I normally code my experiments in coder and haven’t used builder to send triggers, however I do believe the above should work :slight_smile:

Best Regards
Aimee

Hi Aimee,

Thank you so much for your response! I was confused and for some reason thought the frames had to be specified elsewhere but what you say is great. Thank you! I am still a bit confused as to how to populate the start data and stop data sections - would you recommend having another column in the conditions files with the trigger types (e.g. 2, 4, 6) and put the name of this column in ‘start data’ for example? I have two different types of triggers for the frame as well as triggers for the start and end of the movies, (in total I have 6 movie clips)…

All best,
Alice

Hi Alice,

No problem :slight_smile:

Yes, you would need separate columns with the different trigger types and refer to the appropriate columns when needed like you suggested (e.g., in the trigger component refer to the column that has the triggers you want to show for ‘start data’ and another column of different triggers for ‘stop data’).

Best Regards
Aimee

Great, thanks again very much Aimee, really appreciated :slightly_smiling_face: