I have run into an issue when trying to use the ‘Cummulative Time’ column in the output text file to calculate event onset timings/durations, particularly when there is a participant response. I am posting this in the SuperLab 4 support, however, this problem seems to exist in SuperLab 5 as well.
I have (as an example), events with the following assigned durations:
If I run the experiment having the participant withhold responses, I can calculate the following event durations from the Cumulative Time:
However, if I re-run the same experiment, this time having the participant respond as instructed, I calculate the following event durations:
These are clearly not correct. I have tried various ways to linearly combine the reaction times (1812, 0, 2643, 0, 1172, 0, 1794 - participant only responds to events # 1, 3, 5, 7) with the immediately above calculated durations, but I cannot find any logical way to retrieve the information I need.
Unless someone can correct me, the only way I can see to get accurate onset times is to extract them from an experiment run that does not involve any participant responses whatsoever. This should work fine for experiments in which the timings are consistent across all runs (e.g., no inter-subject randomization) but becomes nearly impossible for experiments that include inter-subject randomization. Is there a recommended way to get accurate onset timings for experiments that involve participant responses, as this seems like this should be a requirement for any fMRI stimulus presentation software?
Thanks in advance,