Schedules of reinforcement are developed based on the concept of intermittent reinforcement.Recall that continuous reinforcement is tailor-made for acquiring a new behavior. Intermittent reinforcement then offers itself as an efficient means to maintain that particular behavior. Schedules of reinforcement, therefore, are simply various strategies of intermittent reinforcement.
The first class of intermittent reinforcement strategies is called ratio schedules. Reinforcements in this class are issued on the basis of correct responses. Its elements are fixed ratio and variable ratio schedules. My parents use the fixed ratio schedule of reinforcement. They offer me a delicious and hearty meal after I have earned a high grade, i.e. an A, in an sizable assignment. Variable ratio schedules are obviously more irregular. For example, street vendors do not know and cannot know how long they must wait before a customer stops before them.
The second class of intermittent reinforcement strategies is called interval schedules. It is based on the amount of time elapsed since the last reinforcement. Fixed interval and variable interval schedules belong to this class. The textbook offers monthly salary as an example. My own example would be the weekend. People, myself included, often work hard during the weekdays, getting as much done as possible, so that as much of the weekend as possible could be enjoyed. Variable interval schedules are the most irregular strategy of intermittent reinforcement. One instance (which I wish is real in Vietnam) is when the Ministry of Health unexpectedly check a random food stall. Since the owners of food stall know that they are subject to an unannounced thorough check at any time, they would almost certainly follow all laid down guidelines.
Unlike reinforcement of any kind, punishments are used to remove an unwanted behavior. There are two types of punishment: positive and negative. Both types are widely known, at least in my perspective. Positive punishment is when an undesirable stimulus is issued after an unwanted response is delivered. For example, when I was little, I touched the electric outlet on one occasion. I consequently got a painful electric shock. From that point onwards, I never tough it ever again. Negative punishment is when a favorable stimulus is removed after an unwanted response is delivered. One example of this is the loss of privilege. At my school, students who are tardy on multiple occasions shall receive detention after school, a time during which they may do what they want.
Reinforcement and punishment both have one thing a common. Like medicine, they must be applied correctly and consistently. Improper applications are definitely counterproductive. Punishment, in particular, is prone to abuse (there are many sadists out there). Abuse of punishment can bring about terrible consequences.