Using time variables to show how response time is calculated?
I am creating a reaction time experiment in OpenSesame with some of my students. I know that for reaction time measurement you can use the response time variable that is automatically created for keyboard response items. However, I thought it would be a good idea to show my students how the response time is calculated. So I thought I could just use the time variables to do this, because the reaction time should be the time difference between the time a stimulus was presented and the time the participant pressed a key as a response. I tried different combinations of variables, but I couldn't reproduce the response time given in the data file. I thought if all of my results differed from the response time by the same number of milliseconds, it might be some kind of regular delay, but the differences were variable. Could someone tell me if I'm doing something wrong?
Thank you very much in advance!