Collision Groups Question

What if I have some objects that are just going to be used to determine if the player is in that area, they will not a have a spacial and I will be using the listeners to see when the player is colliding with them. The physics objects will never move or collide with anything but the player. If I put all of them in one collision group, how do I only set them to collide with the player, and not be wasting computation power checking for collisions between themselves? Would I have to put each one in its own collision group? If collision groups work how I think they do, I need some help.

Thanks in advance,

The collision group and collidewith group behavior is explained in the javadoc.