Another innovation created by B.F. Skinner is called the Skinner box. This was an adaptation of Thorndike’s puzzle box, used by scientists to observe how an animal learns to escape the box. Skinner’s innovation was to connect the animal’s behavior (e.g., a rat pressing a bar) to a counting mechanism so that the number of times the behavior was performed would be automatically recorded. This way the frequency of the behavior could be compared across different reinforcement conditions. For example the number of times a rat presses a bar when each bar press is rewarded with a food pellet can be compared with the frequency of bar pressing when the rat is not rewarded with food pellets.