In which type of reinforcement is behavior reinforced for the first response after a varying elapsed time since the last response?

The correct answer is variable-interval reinforcement. In this type of reinforcement, a behavior is rewarded after a period of time that varies, meaning that the time between reinforcement is unpredictable. This unpredictability encourages the subject to respond consistently, as they do not know when the next reinforcement will occur. For instance, in a scenario where a person checks their email and receives notifications at variable times, they are likely to continue checking regularly because they cannot predict when a new message might arrive.

On the other hand, fixed-interval reinforcement involves a set period of time for the reinforcement to occur, leading to a pattern where responses increase as the time for reinforcement approaches but may slow once the reward has been received. Variable-ratio reinforcement provides rewards after an unpredictable number of responses, such as in gambling, which results in high and steady response rates. Differential reinforcement focuses on reinforcing specific behaviors while extinguishing others, rather than timing intervals for reinforcement. Understanding the nuances of reinforcement types underscores how behavior can be shaped in different contexts.