Your brain puts every experience into a pleasant or unpleasant categorization. First experiences program the brain to expect similar results when exposed to similar situations. Horses’ brain work this way, too.
Most horse training is based on strategies that uses things that cause the horse unpleasant experiences so that the horse will behave according to your wishes. Horses are taught to not move unless they are prodded, and then to move quickly or else something else unpleasant will happen. And then to stop or else something painful will occur.
If done with great timing and consideration for the horse’s well being, the horse can learn to accept their powerlessness and live within the human’s world. But is it any wonder that so many people have difficulty catching their horses when they are trained this way?
Positive Reinforcement Training (R+T) and Clicker Training gets put down for using food to train behaviors (in order for the horse to categorize the behaviors we want as “comfortable”. People outside of R+T know that if they gave their horses food after telling their horse to do something it would make them act a bit out of control. Because the horse has so many unpleasant associations with the work that the sudden appearance of food would be completely nonsensical to the horse, too. Or the horse would have to weigh whether the food would signal the appearance of something even more unpleasant that their current situation.
Imagine if a co-worker who often gave you unpleasant jobs to do brought you a big plate of cookies. 
You’d be wondering what was going to come next, wouldn’t you?
With R+T we work with the horses to change their expectations. Nothing bad will happen to you and you can eat all the “veggies” you want, but if do this other thing I ask, you can get even better stuff!! Who wouldn’t want to try for more in that scenario? Over time, we would start having pleasant thoughts just at the sight of the person giving us all these opportunities. We might even follow them around in case they offer us a way to earn something good. Work then really does become about opportunities.
So while R+T does start out with using food and targets, where it goes from there is so much more.
