“…The second DRL variation defines a contingency between responding and a reinforcer following the elapse of a predetermined interval as long as the overall rate within that interval is below a predetermined criterion (Catania, 2013). In some cases, the absence of responding is considered an acceptable dimension, and the characteristic features of maintaining low rates during the DRL schedule are ignored (e.g., Bird, Hepburn, Rhodes, & Moniz, 1991;Hagopian, Kuhn, & Strother, 2009;Shaw & Simms, 2009;Turner, Green, & Braunling-McMorrow, 1990).…”