What characterizes a fixed schedule of reinforcement?

A fixed schedule of reinforcement is characterized by the delivery of reinforcement on a predictable schedule. This means that the reinforcement is provided after a set amount of time or a specific number of responses has occurred. For example, under a fixed interval schedule, a reward might be given every five minutes, and under a fixed ratio schedule, a reward might be given every third response. This predictability helps the individual to anticipate when they will receive reinforcement, which can significantly affect their behavior and motivation.

In contrast, the other options describe various forms of reinforcement that do not align with the concept of a fixed schedule. Random intervals lack predictability, while delivering based on the number of responses describes a fixed ratio but doesn't emphasize the consistent timing aspect. Additionally, the notion of reinforcement being dependent on mood does not reflect a structured or systematic approach to reinforcement schedules and introduces an element of variability that contradicts the fixed nature.