Hierarchy structure in keywords as filters

Aloha all!

I'm relatively new to Bridge, and am enjoying the power is has. One thing that's bothering me, though... I have set up hierarchical keywords which I use extensively. However, when I go to the filter tab to locate photos with a certain keyword, or combination of keywords, every keyword I've entered simply appears in a list. Is there a toggle to get those filter selections to show the heirarchy, including the ability to expand or collapse levels?

Mahalo!

Tom G