A schedule in which reinforcement is tied to the passage of a fixed amount of time is best described as?

• A. Fixed-Interval Schedule
• B. Variable-Interval Schedule
• C. Fixed-Ratio Schedule
• D. Variable-Ratio Schedule

Answer: (A)

Reinforcement that depends on the passage of a fixed amount of time is a fixed-interval schedule. The key idea is that the reinforcement becomes available after a set amount of time has elapsed since the last reinforcement, and the organism must make a response after that interval to receive it. Because responses do not affect when the next reinforcer is available, animals often show a pattern where responding is sparse early in the interval and then increases as the end of the interval approaches, creating a scalloped or burst-like pattern as the time deadline nears. This contrasts with reinforcement based on a fixed number of responses (fixed-ratio) or a variable number of responses (variable-ratio), or reinforcement after varying times (variable-interval). So the description matches the fixed-interval schedule.