keeping track of response choice locations?

[atfrederiksen]

I am working on a comprehension experiment where participants see video recorded sentences and choose their response to the sentence with a button press. I would like to keep track of whether the response they choose is on the left of right side of the screen. 
Right now, I have button location randomized automatically. I can of course undo that and instead create pseudo randomization in my stimulus list by hand. But before I go that route, I thought I'd ask if there is a way keep the randomization and obtain information about response choice locations in the output?
Thanks!