What does fixed ratio reinforcement require before a reinforcer is given?

Fixed ratio reinforcement requires that a specific number of behaviors must occur before a reinforcer is provided. This means that the reinforcement is contingent upon the completion of a set number of responses. For example, if a child receives a sticker after completing five math problems, the reinforcement (the sticker) is given only after the predetermined number of behaviors (completing five math problems) is achieved. This approach leads to a high rate of response as the individual knows exactly how many behaviors are required to earn the reward and can adjust their efforts accordingly.

The other options do not accurately describe the characteristics of fixed ratio reinforcement. Variability in behaviors or timing is not part of this concept, as fixed ratio specifically emphasizes a set number of responses linked to the reinforcer.