With operant conditioning we utilize a variety of reinforcers. Reinforcers are the things that animals want to work for, but more specifically they are the things that change behavior. Often times, these things are called rewards. There is actually a bit of a difference between a reward and a reinforcer. A reward is something you give to an animal or person because of something they did, but if that doesn't actually change their behavior is isn't a reinforcer. The key to a reinforcer is that the timing actually will change the animals behavior. For example, increasing their chance to go into a down position when you ask for "down".
Often times people think of food as the reinforcer. While this is often the most used due to how easy it is for us to use, it isn't the only reinforcer. Anything the animal likes and wants can be used as a reinforcer. This includes attention from family member and also toys or play. What the animal desires and is willing to work for can even change over time, even within a single training session. Remember to be flexible when offering reinforcers. The animal chooses what they like, you can't change that. Just like another person can't change your taste for food, movies, or other forms of entertainment. Having trouble figuring out what your dog likes? Experiment a bit. What makes their eyes go wide with excitement? The simplest rules of reinforcement is that animals orient themselves towards reinforcers and away from punishers. Simply changing the reinforcers you are using can go a long way in increasing your training plan.