Can a visual target be displayed with a speed lower than one pixel per frame with the psychtoolbox?

I am writing a program for a psychophysics experiment aimed to get visual motion detection thresholds. I have two questions:

1. I display my visual target in a different position on every frame (like in a movie) to create a moving visual target. Can I have a motion which is lower than 1 pixel per frame? In order to make my target moving toward right, I added the vector [0 1 0 1] to its original position. I have also tried to randomized the speed with [0 1 0 1]*rand. However I am not sure if in this case the speed would be lower than one pixel per frame since “rand” is a number between 0 and 1. However I can see some differences in the visual motion...

2. Is there a way I can set the frame rate in matlab? For now I have the computer’s refreshing rate sets at 60Hz…

Thanks!

Valentina