[edited by moderator]
I have been running a few experiments in which I use two "stim" columns in the same line, both requiring response. In the log output file the "correct" column corresponds to the actual "correctness" about 80% of the times, but the other 20% do not correspond. For example, if I program the response to be rt:32,37 then if the participants pressed 32 it will say "true" for ~ 80% of the trials but for some reason it will say "false" for ~20% of the trials. I've gone back to look at several other experiments and this is the case in all of them. It doesn't happen if there's only one "stim" column per line. That means that when there is more than one "stim" column than requires [a] response [that] the "correct" column [may not] provide the [correct] data. [...]