Stroop Task - Present Multiple Images & Record Multiple Responses

Hi. I am trying to create a Stroop Task which involves presenting an array of pictures (4x4 and 8x5) simultaneously, and then allowing the subject to click on multiple pictures. I would like to be able to record which pictures were pressed and the RT for each picture pressed, and have some visual indication that the picture was pressed (e.g., picture disappears or an X goes over the picture). I have figured out how to set up the screen areas using a text file, and to present all the stimuli simultaneously using compound screens; but I am having trouble figuring out how to record the responses. Would anyone be able to help me with setting up this task?

Thank you.