What schedule provides reinforcement for the FIRST CORRECT response after a variable duration of time occurring in a random or unpredictable order?

• A. FIXED INTERVAL
• B. VERIFICATION
• C. VARIABLE INTERVAL
• D. VARIABLE TIME SCHEDULE

Answer: (C)

This question hinges on how a variable interval reinforcement pattern works: reinforcement is delivered for the first correct response after a time interval that varies unpredictably. The key is that the interval length changes and the reward comes only after some elapsed time, not after a fixed moment, and it’s tied to a response. Because the timing is unpredictable, the learner keeps responding at a steady, moderate rate rather than slowing down or peaking at specific moments.

If the interval were fixed, you'd see a pattern where responses accumulate and then drop after reinforcement, creating a scalloped curve as the end of the interval approaches. A variable time schedule would deliver reinforcement on a changing clock regardless of any response, so it wouldn’t depend on the first correct response after an elapsed interval. A distractor option named verification does not describe a standard schedule pattern.