Like the rat in the cage we are driven by rewards. It's only human and also perhaps rat nature. Suffice it to say it's nature.

So when compensation, the reward, becomes stagnant so does productivity. If like rats we are paid by the time we spend in the cage, then the expected level of productivity is simple compliance.

By focusing on minimum standards employees tend to get there and stay there; a comfort zone or twilight zone or Bermuda Triangle whatever else it can be called.