So as not to hijack Zooby's thread "Eyes in the back of your head", I am posting this in a new thread. Our physical sense of balance is tied to our sense or hearing...but I think it really comes under our sense of touch. http://webschoolsolutions.com/patts/systems/ear.htm I maintain this is just a matter of how we choose to define things. I think it has always meant the senses that we currently acknowledge. I have never seen this as the definition...this only serves to make ESP impossible by definition. If we find a new sense, one that explains previously unsubstantiated claims, then this is what we have always meant.