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stimulus assignment to condition

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Posts: 2
Topic starter
(@mspeiger)
New Member
Joined: 1 month ago

Hi, I have an issue with my stimulus naming in Homer.
In my experiment I have 4 conditions that are counterbalanced across participants. To differentiate the conditions I sent 4 different stimuli. Now in the .evt file these stimuli are correctly sent depending on which condition was shown first. But when I open the .nirs files in Homer the stimuli are always numbered from 1 to 4, no matter in which order the conditions were presented. Thus, I am unable to look at group averages because the conditions get lost there.

I am sure I am missing something here, but my question ist:

How can I get Homer to name the stimuli according to what has been sent (and recorded as ahown in the .evt file) and not simply always from 1 to 4?

Thank you in advance, I appreciate any help 🙂

3 Replies
Meryem Yücel
Posts: 211
(@mayucel)
Joined: 4 years ago

Hi Marie,

 

Do you have the .tsv files with trial info along with your snirf files under the subject folders? If so, the later versions of homer should automatically read the stim info from the tsv files. Is the order correct in all of your tsv files?

 

Meryem

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Posts: 2
Topic starter
(@mspeiger)
New Member
Joined: 1 month ago

Hi Meryem,

thank you so much for your reply.
Yes we tried it in different versions of Homer and have the same problem in all of them. In the newer one we saw that the problem is, that the newly created tsv file does not use the informiation that is given in the original .evt and .hdr files (with the stimulus information)that were used to compile the .nirs file (and then the .snirf file). Is there a way to change how the .tsv file gets the information of the stim (because there is the issue)? I think that at the moment it is just ordering the stimulus info from 1 to 12 not taking into account the assignment and in which order it was sent and recorded in the original files.

Thank you very much
Best,
Marie

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Meryem Yücel
Posts: 211
(@mayucel)
Joined: 4 years ago

Hi Marie,

 

Homer initially reads stim info from snirf files and write it into event.tsv file for each subject/run, and in later launches it directly reads from event.tsv files. It does not read from any .evt or .hdr file that you may have. So once homer creates the event.tsv files, you need to correct the info in those files.

 

Meryem

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