 DRD, Differential Reinforcement of Diminishing Rates of Behavior, which I don't know why isn't a DRD ROB. But anyway, differentially reinforcing diminishing rates. So if I start out speaking like this, it's speaking very fast, right? So you could then start to reinforce me as I start to speak a little bit slower. Then if you still don't think that I'm speaking slow enough, you could reinforce me when I start speaking at a rate about like this. And now that I'm speaking at a rate about like this, you could reinforce me if I start to speak a little bit slower. Now we are reinforcing a diminishing rate of behavior. As my rate is decreasing, then you are delivering reinforcers. At some point, my rate might get a little too slow. So you might have to engage in an alternative behavior in order to reinforce me back up to a particular level. But anyway, the point is that you differentially reinforce the organism as the behavior rate lowers. That's it. Diminishing rates, diminishing, decreasing, drifting, depleting.