Instructions. Identify the reinforcement schedule illustrated in the following examples by placing the appropriate abbreviation in the blank next to the item. Use the following code:
Fixed Ratio (FR) Variable Ratio (VR) Fixed Interval (FI) Variable Interval (VI)

1. Getting a paycheck every other week
2. Pop quizzes
3. Slot machines at gambling casinos
4. Calling the mechanic to find out if your car is fixed yet
5. A factory worker who is paid on piece work
6. Fly fishing: casting and reeling back several times before catching a fish
7. Looking at your watch during a lecture until the end of the lecture
8. A salesperson who gets paid on commission
9. Calling a friend and getting a busy signal because he or she is frequently on the phone
10. Signaling with your thumb while hitchhiking
11. Frequent flyer program: rewards after flying X amount of miles
12. Collecting bottles, cans, or other recyclables for cash
13. An athlete's contract specifies salary increases to be renegotiated every three years
14. Buying lottery tickets
15. A person refrains from drugs for fear of random drug testing
16. Checking the refrigerator to see if the JELL-0 is ready
17. Watching for shooting stars
18. Checking the mail, assuming the mail carrier comes at the same time every day
19. Check email
20. Playing Bingo