Continous sliding bar for ratings

[David Maillet]

Hi,

I want participants to give ratings on a scale of 1-100 by sliding a bar. This is for an fMRI study with few response buttons. So I would like the bar to start in the middle (at 50), holding one button would move it left, holding a second button would move it to the right, and a third button would advance to the next screen once participants are done. I'm working with eprime1.

Any help on how to do this is appreciated!

Thanks,
David