1. Variable-interval schedule of reinforcement—define it and give an example. 

2. Explain the difference between the concept of variableinterval schedule and the principle of variable-interval pattern of responding. (At quiz time, people get confused with this one.) 

3. Describe the procedure and behavioral results of a variableinterval 2-minute schedule of reinforcement (VI 2′). 

4. List three characteristics of variable-interval schedules. 

5. Students often blow this one: On a variable-interval schedule of reinforcement, must a response occur before the reinforcer is delivered? 

6. Relatively speaking, describe the response rate with a variable-interval schedule if the time intervals between reinforcements are small or the time intervals are big.