First Trial Jitter Delay Issue in fMRI Audio-Visual Experiment

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1

Psychopy version: 2022.2.4
I’m running an fMRI experiment with audio (.wav) and visual (jpg) stimuli. After each trial, I introduce a random jitter during which participants provide ratings. A fixation cross appears before the next trial. The issue I’m facing is that the jitter delay in the first trial is longer than intended, while the subsequent trials run smoothly. Any suggestions to resolve this?

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Hi Ajay,

I wonder if the issue is because you might be loading a sound on the first trial (e.g. via a code snippet).

If you have a basic experiment with the same sound every trial (where the path to the sound is in the sound component) - do you get the same lag on the first trial?

Becca

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Just as a follow up to this - if that does fix the experiment, try having two sound components in your routine where the sound is presented, and instead of controlling the path via a code snippet control the volume of the two sound components via a code snippet instead (i.e. to turn on/off the relevant sound for that trial)