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Editing stim marks and Data type index

Posts: 6
Topic starter
Active Member
Joined: 1 year ago

Hello everyone,

I am using Homer3, v1.33 on Matlab version 2021b on a Macbook. I have 2 questions:

Q1 (task description below): Is there a way to label my stimuli as test and silent conditions, so that I only calculate HRF for the test stimuli? I came across a tutorial on Homer that suggested dragging the mouse over the stimulus and toggling it on/off, but selecting will not be feasible as I have over 100 stim marks/triggers in the stimulus window. I also changed the amplitude value of those stimuli from 1 to -1 and saved it to the original file, but this didn’t turn off those stim marks either (it didn’t turn to dashed line).

Q2: After I run the analysis pipeline, it generated a matlab file for each participant in the ‘HomerOutput’ folder. In one of the cells in the dvAvg measurement list, there are 3 different outputs labelled as data type index (1,2,3).
What are these data type index? It is not similar to HbO or other types of concentrations, so I am not sure what these data type indexes mean.

Task description for Question 1: In this task, participants heard a nonword plus a sound and they were instructed to delete the sound from the word and say the word again. There were 65 stimuli presented, out of which 15 were silent conditions (i.e., there was no sound played and no response was made). We used EPrime to program the task and it sent triggers at the beginning and end of each stimulus but there was no way to label the test and silent conditions in the EPrime (because the presentation of both types of stimuli was random).

Thank you!!

1 Reply
Meredith Pecukonis
Posts: 16
Active Member
Joined: 2 years ago

Hi! I am also having a similar issue: when I change the amplitude value from 1 to -1 in the third column of and saved it to the snirf file, the stim marks don't seem to be turned off (they dont show up as dashed lines in Homer GUI. Are these stimulus trials removed from processing or not? If not, what is a simple was to remove/toggle off "bad" trials that I don't want to be processed?