Variable ratio schedules of reinforcement provide reinforcement after an average number of responses. Words or gestures of appreciation, given at random intervals, are reinforcing. What are more wiggly than fixed ratio! The study of the mind has actually come up with quite a few findings that can inform game design, but most of these have been published in scientific journals and other esoteric formats inaccessible to designers.
This is because positive reinforcement makes the person or animal feel better, helping create a positive relationship with the person providing the reinforcement. Make it clear what the reward is for and why the player got it. There was some problem while copying. If she is expecting something valuable like a treat and is given something less exciting like a barbie to play with later instead, she will be much more disappointed than if she was expecting the barbie all along.
In another example, Carla earns a commission for every pair of glasses she sells at an eyeglass store. With the help of the community we can continue to improve our educational resources. This is a private resource. PR schedules, for without stable theories to anchor them, empirical results are quickly swept away in the flood of new data.