From Dan T: A Positive Reflex happens when your horse is "hunting for you and your focus" and trying to help you accomplish what you're doing.  

This relates also to something else I have been considering: changes in the way the horse thinks about learning as he progresses through the levels toward partnership/positive reflex. For an older performance horse who has been told what to do and is obedient-- to shift to puzzling things out WITH the human in an active, creative way is something very lovely. I enjoyed playing with Spiderman those two months and he was a good learner of task but so different from Try in thinking and involvement/commitment. It showed me a new perspective on the journey.