Which reinforcement schedule provides reinforcement after varying numbers of responses?

The reinforcement schedule that provides reinforcement after varying numbers of responses is referred to as a Variable Ratio schedule. In this type of schedule, the number of responses required for reinforcement changes unpredictably. This means that the subject does not know how many responses will be necessary to obtain the next reinforcement, which often leads to high and steady rates of responding.

This unpredictability is particularly effective in maintaining behavior because it creates a sense of anticipation; the subject is motivated to continue responding as it could lead to reinforcement after a varying number of responses. An example of this in practice is gambling, where a player may win after several attempts, but the exact number of attempts required to achieve a win is unknown.

In contrast, other schedules such as Fixed Interval or Fixed Ratio provide a consistent number of responses or a specific time period before reinforcement, making them less effective in maintaining a high rate of responses over time due to predictability. Variable Interval reinforces after varying time periods but does not focus on the number of responses. Thus, the Variable Ratio schedule stands out as it is centered around response variability and unpredictability in reinforcement, making it effective in behavior reinforcement strategies.