Listselect selecting on down arrow

When the listselect has focus and I press the down arrow or up arrow (along with a few others), instead of scrolling to the next item, it selects the one I am on. I would like it to instead only select an item under 3 conditions.

  1. The user presses enter - right now it does not select the current item when enter is pressed.
  2. When the user clicks on the item, that works correctly
  3. When the user keys in enough information to identify the item, that also works.

Any ideas about how to make that happen

Thank you