What duindain was asking...but ..
Exactly, so in my experiment what I want is:
Hitting spacebar is correct, hitting nothing is incorrect, but for the spacebar to be correct - it has to be hit within 500 ms of stimulus presentation (pretty much at the time the stimulus is presented).
Similiar to duindain - the next stimulus in the trial only comes up if the participant hits the spacebar key. Doing nothing doesn't advanced the stimulus to the next one within the same trial.
Can someone help? Can you show me exactly what I should type in to the 'time' box? Right now, I have rt: 57,-1 but I don't know how to set 57 for 500 ms.