I am attempting to use DirectRT for a psychology experiment. What I need the program to do is to require a correct response to math problems, meaning that the participant needs to type in the correct answer before moving on to the next question. However, I cannot get DirectRT to require a response that is multi-keyed; I understand how to require one correct key before moving on, but even when I introduce multiple responses to the trial, I cannot get the program to require the correct response. I also understand how to allow for a free response with DirectRT, but as far as I can tell you can't require a free response to be "correct." Do you have any suggestions for me? Is MediaLab able to require such a correct response?