Hmm. Perhaps, you could use the randomization functions to set the location values when DirectRT reads your input file--i.e., randomize the actual LOC values of the DOT image. Take a look at this link and see if it's helpful:

http://www.empirisoft.com/directrt/h...dom_values.htm

For example, when placing a stimulus image of a dot, you might try the following for a LOC value:

rand(.25,.75),.5,0

That would randomly place it on the left or right side of the screen, and half way down. Does that make sense?