I have an experiment in which I want to send triggers to an external device in case the participant gives a correct response. Those triggers should be send randomly in 10% of the correct trials. I programmed it in a way that every time a correct response i given, a responsetrial is executed. In this response trial, I first present an empty screen (feedback_leer) and then after 1500 ms this empty screen is either repeated (thus nothing happens) or in 10% of the trials the TRIGGER is send.
<port Trigger>
/ port = lpt3
/ subport = data
/ items = (255)
</port>
<trial potential_trigger>
/ posttrialpause = replace(3500, 4000, 4500, 5000, 5500, 6000, 6500)
/ stimulustimes = [0=feedback_leer, Marker_Response_Control_L; 1500=replace(feedback_leer, feedback_leer, feedback_leer, feedback_leer, feedback_leer, feedback_leer, feedback_leer, feedback_leer, feedback_leer, TRIGGER)]
/ timeout = 1000
</trial>
This works fine. The only problem is that I just realized that what I need in those 10% is not one trigger but three triggers send in intervals of 50 milliseconds. Is there an easy way to do this? Or does it involve branching to another trial everytime the trigger is chosen? And if so, how would such a /branch look like: how can I say that I need the branch trail every time the TRIGGER is chosen as stimulus?