What schedule requires a varying number of responses to produce reinforcement?

• A. FIXED RATIO
• B. VARIABLE INTERVAL
• C. VERIFICATION
• D. VARIABLE RATIO

Answer: (D)

Reinforcement schedules describe how responses are strengthened by presenting reinforcement based on either the number of responses or the passage of time. The schedule that requires a changing number of responses to obtain reinforcement is the variable ratio. In a variable ratio schedule, reinforcement occurs after an average number of responses, but the exact number varies unpredictably. This unpredictability keeps responding high and steady because the next response could be the one that yields reinforcement, so there is little or no post-reinforcement pause. In contrast, a fixed ratio requires a set number of responses before reinforcement, producing bursts followed by pauses; a variable interval delivers reinforcement after varying time intervals, yielding steady responding with more pauses; the option labeled verification is not a standard reinforcement schedule.