**OS: MacOS Catalina
**PsychoPy version: v2021.1.2
**Standard Standalone? yes
**What are you trying to achieve?: I’m running a builder task in an fMRI study for which I need good keyboard response timings. Although the timings for the stimuli onsets line-up across the .csv and .log files, I am getting different times for when the keyboard response occurs across the two. Specifically I am looking at the timings for DATA Keypress in the log file, and the timings when adding the resp.rt to the resp.onset in the csv files. I don’t know why these inconsistencies exist in the first place but they are up to 200ms difference so it’s not just a matter of frames.
What did you try to make it work?:
-checking and unchecking the ‘Sync timing with screen’ in the keyboard response component
-experimenting with the order of the response component in routine
What specifically went wrong when you tried that?:
-Neither change was able to eliminate the variability in the RTs across the two files. Notably the reaction times aren’t consistently different – sometimes they are the same across the files, but there also seems to be a peak in the histogram at about 125ms difference. See attached histograms of two separate subjects.