I find this to be the most confusing thing that Parelli's thought of. Some horses fall into several categories depending on their mood, location where you work them, etc. A horse can be bold in the arena but timid on the trail, etc. I don't see how they can lump horses only into categories. However, I have met horses that totally did fall into one of those categories. But some don't easily fall into their left brain, right brain.
What do you think about horsenalities? Can you personally label your horse as one horsenality?