How to get a screen to turn blank on its own?

Hi. I'm new to psychtoolbox and MATLAB. I've been using the Ask
command. How do I get this screen with text to turn blank on its own?
Right now I think it has the default "GetClicks" thingie, so I need to
type a key to get the next screen.

There must be a way where the screen goes blank on its own...?