FR (fixed ratio) - the reinforcement is delivered only after a certain fixed number of correct response have occurred
VR (variable ratio) - the reinforcement is delivered only after a variable (unpredictable) number of responses hsve occurred
FI (fixed interval) - reinforcement is delivered after the first response that occurs after a specific interval of time has passed
VI (variable interval) - reinforcement is delivered after the first response occurring after a variable interval of time has passed


____ Police stop drivers and give them a prize if their seatbelts are buckled; seat belt use increases in town.
____ A basketball player who commits a flagrant foul is removed from the game; his fouls decrease in later games.
____ A soccer player rolls her eyes at a teammate who delivered a bad pass; the teammate makes fewer errors after that.
____ The annoying child jumps up and down, hand raised, yelling "Me, me, me!" until the teacher calls on her. The child jumps and yells even more in the future.
____ After a good workout in physical therapy, hospital patients are given ice cream sundaes. They work harder in later sessions.
____ The employee of the month gets a reserved parking space. Employees now work harder.
____ A dog is banished to his doghouse after soiling the living room carpet. The dog has fewer accidents after that.
____ You clean up your stuff more regularly now to avoid your roommate's (or mother's) nagging.
____ You get paid once every two weeks.
____ A worker is paid $2 for every 100 envelopes stuffed.
____ Slot machines at casinos payoff after a variable number of plays.
____ Students are released from class when the end-of-period bell rings.
____ You get a nickel for every pop can that you return.
____ Every time you buy a sandwich you get your card punched; after 10 punches you get a free sandwich.
____ Sometimes the mail is delivered at 1:00, sometimes closer to 2:00.
____ Every so often you like to surprise your special other with something nice.