An MO is best described as a stimulus that does what?

• A. Evokes a behavior independent of reinforcement
• B. Evoke or deter a behavior because it alters the value of a reinforcer
• C. Provide punishment
• D. Create a schedule for reinforcement

Answer: (B)

Motivating operations change how valuable a reinforcer is in the current moment, which in turn changes how likely a behavior that has produced that reinforcer will occur. They have a value-altering effect (they make a reinforcer more or less valuable) and a behavior-altering effect (they evoke or abate the behavior that has produced that reinforcer). For example, thirst increases the value of water; as a result, water-seeking or water-asking behaviors become more likely. Once thirst is quenched, the reinforcer’s value drops and those behaviors lessen. This is why the best description is a stimulus that makes a behavior more or less likely because it changes the reinforcing value of the outcome. It’s not about punishment or creating a reinforcement schedule, and it’s not simply about evoking behavior independent of reinforcement.