psychopy.org | Reference | Downloads | Github

Timing Problems in Psychopy

OS (e.g. Win10): Win10
PsychoPy version: 1.90.1
Standard Standalone? y

I built a fmri task that has two routines in a loop. One routine I’ll call ‘task’, the other i’ll call ‘jitter’.Each line of the conditions file represents one trial and there is a variable for ‘trial_type’ that specifies whether the trial is a ‘task’ trial or a ‘jitter’ trial. I added a code component to each routine that, at the beginning of the routine, checks the trial_type for the current trial and continues the routine depending on the trial-type. So for the ‘task’ routine, it checks whether the trial-type is ‘task’ and continues the routine if so, otherwise it does not continue the routine. For the ‘jitter’ routine, the code component checks whether the trial-type is ‘jitter’ and continues the routine if so, otherwise it does not continue the routine. Below this code component, I added a second code component in each of the routines to timestamp the onset of the routine (relative to the start of the run; you explained how to do this in another post I had on this forum). Below these code components, I have the other code components relevant to the trial type–so visual stimuli presented for specified durations. The question I have regards timing–I looked at the timestamps in my output file and there are some super bizarre instances that make no sense. For example, the ‘task’ trial takes 1.5 seconds, and the timestamp for a task trial was immediately followed by a timestamp for a jitter trial (like hundreds of seconds apart), even though that’s impossible because 1.5 seconds would have elapsed before the task trial was over and a jitter trial began. I ran through the task and didn’t notice anything aberrant in the presentation, so I believe it is something specific to the way my code and timestamping is set up. Is there something inherent in the way I designed the task and the ordering of my code components that would lead to this wonky problem? Please let me know if there’s other information I can provide. Thanks so much!

HI @bungarotoxin, would you be able to provide is with a minimal working example of your experiment?

Stroop_experiment_082618_NO_wait_for_trigger.psyexp (118.1 KB)

I’ve attached the psyexp file, is this what you wanted?
In my previous post, I meant to say the timestamps were hundredths of seconds apart, NOT hundreds of seconds apart, my apologies.