I am trying to set up a dot-probe task in DirectRT in which 2 stimulus words appear, one on either side of the screen, followed by the random presentation of a dot on one side. I have worked out how to set up the compound screens and randomise the location of the dot but I am unsure how to co-ordinate the locations of the initial compound screen stimulus and the following stimulus so that they alternate randomly between the left and right side of the screen, without appearing on the same side at once.

Thanks