Evaluations for input

C

Expected Answer: A

Difficulty: Easy

Subfield: Biological Psychology

Explanation: Ratio reinforcement schedules are characterized by their rapid response rates, and variable ratio schedules occur when the response is reinforced after a random number of responses. For example, in a lab setting, a rat may receive a food pellet after pressing a bar once, then four times, then three times, then once again. Since (A) shows the delivery of a reinforcer after a random number of rapid responses, it is correct. (B) indicates a fixed ratio schedule, in which a response is consistently reinforced after a specific number of responses have been performed. Like the variable ratio schedule, the response rate is high. However, during this schedule, there are pauses after reinforcement, indicated by the horizontal components. (C) indicates a variable interval schedule, in which a response is rewarded after a random amount of time has elapsed. This schedule is characterized by low and steady response rates. (D) indicates a fixed interval schedule, in which the response is rewarded only after a specific amount of time has passed. It can be easily identified by the lack of responses directly after the reinforcer is administered (the flatter regions), and the subsequent increase in responses near the end (the steeper regions) of the interval. (E) represents a scenario where the behavior is already being performed and the addition of a reinforcer has no effect on the response rate.