What type of reinforcement schedule provides reinforcement only after a specified time has elapsed?

A fixed-interval schedule is characterized by reinforcement being provided after a specified amount of time has passed. This means that the first response made after the fixed period has elapsed will result in a reward. This type of schedule leads to a pattern of responding that involves a significant pause immediately after the reinforcement is received, followed by an increase in response rate as the next reinforcement time approaches.

For instance, in a fixed-interval schedule, a student might receive a quiz every two weeks. Initially, they may not study much after receiving a good grade, but as the next quiz date approaches, their studying will increase. This schedule is particularly effective for establishing a predictable pattern of behavior because the subject learns the exact timing of the reinforcement.

The other schedules mentioned operate differently: a variable-ratio schedule provides reinforcement after an unpredictable number of responses, while a fixed-ratio schedule reinforces after a set number of responses, and a variable-interval schedule delivers reinforcement after varying amounts of time have passed, making the timing of reinforcement less predictable than in a fixed-interval schedule.