Imagine that you are training a pigeon to peck at a key to receive a food pellet. You put the bird on a variable-interval 30 (VI-30) schedule. This means that the pigeon will receive reinforcement an average of every 30 seconds. It is important to note that this is an average, however.
interlocking reinforcement schedule Cite this page: Nugent, Pam M.S., "VARIABLE-RATIO REINFORCEMENT SCHEDULE (VR SCHEDULE)," in PsychologyDictionary.org, April 29, 2013, https://psychologydictionary.org/variable-ratio-reinforcement-schedule-vr-schedule/ (accessed June 17, 2018).