However, the monkey’s response to being cut off from the reward is very different if you start out on a purely random schedule, instead of a consistent one. When you stop offering the reward, there’s no way the monkey can know that it will never be rewarded again for doing that task. Every time it was rewarded in the past, the reward came as a surprise. As a result, from the monkey’s perspective, there’s no reason to quit doing the task. The monkey keeps on doing the task, even without being rewarded for doing it. Some will continue indefinitely.
