What defines partial reinforcement?

Partial reinforcement is characterized by the idea that reinforcement occurs only occasionally rather than every time a behavior is exhibited. This approach creates a situation where the reinforcement is unpredictably delivered, which can lead to more robust and persistent behaviors compared to continuous reinforcement, where the behavior is rewarded consistently.

When reinforcement is not guaranteed with every occurrence of the behavior, it often leads to stronger learning and greater persistence of that behavior over time because the subject learns to keep engaging in the behavior in the hopes of occasional rewards. This can be effective in various training scenarios, including behavior modification and habit formation, as it helps maintain motivation without becoming reliant on constant rewards.

In contrast, the other options represent forms of reinforcement that are not considered partial. Reinforcement every single time a behavior occurs reflects continuous reinforcement, and reinforcement offered on fixed schedules or based solely on time intervals would indicate specific reinforcement schedules that are structured differently than the unpredictable nature of partial reinforcement.