Require Multiple Keypresses
…\DirectRT\samples\6- v2006\require multiple keypresses
With the use of an external text file, e.g., rt1.txt, you can list separate sets of valid keycodes for a SINGLE stimulus. Doing so will require the participant to hit a valid keycode from each set. This will allow you to take two simultaneous keys for each response--and you'll be able to get the RT for each no matter which one comes first (even if the difference is a small number of milliseconds).
In the sample external text file "rt1.txt" in the stim folder, we see two sets of valid codes: the z (44) or x (45) key, and then the . (52) or / (53) key. This means that one key from each set will be required as a response.
In the input file "double.csv," see that where we would normally say "RT:..." we say "RT1:44,53"
This means that we want to use the rt1.txt file in order to use rt key sets (any value up to "RT9" can be used for the text file). The 44 indicates that the correct response from set 1 is 44 (z), and that the correct response from set 2 is 53 (/). You can add or change the keycodes in the rt1.txt file as you like. You can also change which keys are correct in the input file.