Which procedure involves changing reinforcement contingencies by gradually increasing the response ratio or the duration of the time interval?

• A. Stimulus Class
• B. Social Validity
• C. Withdrawal
• D. Schedule Thinning

Answer: (D)

Schedule thinning involves changing reinforcement contingencies by gradually increasing the response ratio or the duration of the time interval. In practice, this means you keep reinforcing the target behavior but do so less often, or after more work, so the behavior stays strong as reinforcement density decreases. For example, you might start by giving reinforcement after a small number of correct responses or after a short interval, then slowly increase the ratio or lengthen the interval while continuing to reinforce appropriately. This helps maintain the behavior and supports independence as reinforcement becomes thinner. The other terms refer to different concepts: stimulus class groups stimuli that evoke the same response, social validity concerns whether an intervention is acceptable or meaningful to those involved, and withdrawal means removing reinforcement or stopping an intervention rather than systematically reducing reinforcement density.