In ABA, what does a Variable Interval schedule entail?

A Variable Interval schedule is characterized by the delivery of reinforcement after variable amounts of time have passed, making it unpredictable for the individual when the next reinforcement will occur. This creates a situation where the response is maintained over time, as the individual is not aware of when exactly the reinforcement will happen, encouraging consistent behavior rather than at set intervals.

In contrast, the other choices describe different types of reinforcement schedules. A fixed amount of time between reinforcements would describe a Fixed Interval schedule. A set number of responses required for reinforcement is a characteristic of a ratio schedule, specifically a Fixed or Variable Ratio schedule. Lastly, specifying reinforcement after a certain number of occurrences also corresponds to the concepts of Ratio schedules, but does not align with the unpredictability inherent in a Variable Interval schedule. Hence, the definition of the Variable Interval schedule focuses on the variability and unpredictability of time between reinforcements.