Hello,
I am creating a dot probe task in DirectRT, and would like several of my fields to be randomized (location for stimuli pairs, time for display of stim, and location of subsequent dot probe). For example, I want 30 trials to be presented with each time duration (250ms, 500ms, and 1250ms), but I want these durations to be random. The user manual has been very helpful in brainstorming several ways to accomplish what I want, since I want several fields to be random in this way.

I also checked out this thread: http://www.empirisoft.com/support/showthread.php?t=1632 as I'm thinking about using the rand(250,500,1250) function for each stim pair. I'm wondering if there is any way to specify or guarantee that I'd like an equal number of trials to be 250ms, and 500ms, and 1250ms? Or, using this rand() function, will it just be "about equal" but no way to guarantee that 30 trials of each will be presented?

Hope this makes sense. Thank you!