Which reinforcement schedule provides reinforcement at unpredictable time intervals?

The variable-interval schedule is characterized by providing reinforcement based on unpredictable time intervals. In this type of reinforcement schedule, the timing of the reinforcement varies, meaning that the participant cannot predict when the next reinforcement will occur. This uncertainty encourages consistent behavior over time, as the individual learns that their responses are more likely to be rewarded at unpredictable moments rather than in a regular pattern.

For example, consider a scenario where a person checks their email. If they receive emails at random times throughout the day, rather than after a certain fixed period, they are more likely to check frequently, unsure when the next email will come. This unpredictability in the timing of rewards can lead to a high rate of responses because the person is consistently attempting to engage in the behavior that might lead to reinforcement.

In contrast, fixed-interval and fixed-ratio schedules involve set patterns of reinforcement, with specific time periods or response quantities that lead to rewards, while the variable-ratio schedule provides reinforcement after varying numbers of responses but does not relate to time intervals.