Which reinforcement schedule rewards a response after an unpredictable number of responses?

The correct answer is the variable ratio schedule, which rewards a response after an unpredictable number of responses. This type of reinforcement schedule is particularly effective in encouraging high rates of responding, as the individual learns that a reward can come at any time, depending on their effort. Unlike fixed schedules, where rewards are delivered at consistent intervals or after a set number of responses, the variable ratio schedule creates a sense of anticipation and excitement, similar to gambling—where players do not know when the next win will occur, prompting them to keep trying.

This unpredictability fosters persistence and can lead to robust behaviors since individuals are incentivized to continue their actions without knowing precisely when they will be rewarded. This kind of reinforcement is commonly observed in various scenarios, such as slot machines in casinos or lottery systems, where individuals may gamble multiple times without knowing when they might hit the jackpot.

In contrast, the other reinforcement schedules offer predictable outcomes. A fixed interval schedule delivers rewards after a specific amount of time, a continuous reinforcement provides a reward after every response, and a variable interval schedule rewards after unpredictable time periods. These characteristics differentiate the variable ratio schedule, highlighting its unique effect on behavior.