Driving on snow (lots of recent experience) you get some experience with this. There is a yellow triangle symbol on the dash that comes on when a wheel is slipping and you get a grinding like sound when the other wheels pick up the slack. I think it's a situation where it only engages when a wheel loses traction. I don't know if that just the AWD or the variable traction control (or what ever they call it).
Driving the CRV in snow is great compared to previous cars I've owned. Anti-lock brakes and the AWD makes is so much safer.