 I think we'll start this out with an example of a Hilbert chain, as you're going to have eight pairs. You grab by the function fuller. We might be wrong. We're funny, but not always the same. Back to the issue at hand. We're working on target behavior still, but we need to focus on some definitions right now. So, there's a couple of things we need to remember. There's basically, in a nutshell, two types of definitions that we, as behavior analysts, like to work with. However, we do prefer one over the other. The one that we do prefer is the function-based definition. Okay? Why a function-based definition? Well, just because. Trust me. That's all you need to know. You grab them by the function, as somebody once said. Twist. Function-based definitions, what that allows us to do is work with any target behavior in a particular response class. Okay? So, a response class, again, remember any response that produces a particular function. So, when we identify the function of behavior using an ABC analysis or whatever tool we're going to use to get at the function, then we can define the behavior in that context. That makes it really clear, really concise, and really easy to work with. Because then we can start talking about replacing that particular behavior with another behavior that's appropriate, yet serves the same function. You see the idea, right? But we don't always get function-level data. There's a lot of reasons why we might not. Number one being, it's difficult to get function-level data. So, maybe we're going off some indirect assessments. Maybe we're going off some interviews, and we don't have that. Maybe what we've got is how the behavior looks, right? So, dancing is, we could look at a functional definition of dancing, and I know I suck, and I don't care. So, we could look at a function definition of dancing, or we could look at a topographical one. Topographical is how I'm dancing. You might be more interested in shaping the topography of my response to dance better, right? Then you're focusing on a topographical definition. How does the behavior look itself, right? What do you see? What's there? What sort of movements do you need the person to engage in? What words do they need to use, right? But the function really didn't change. Just dancing, having fun with the music, entertaining you, whatever the case may be. So, the dancing part, the function stayed the same, but we actually wanted to tweak the topographical definition. It's easier in our line of work to work with the functions, but sometimes you're just left with the topography for many reasons. So, ultimately though, when we are focused on topography, we want to make sure that the topographical response that we're choosing, the response that we're looking at, at least leads us to a function that we suspect is happening, right? That sounds like I'm kind of talking in circles, but I'm just saying, if you're going to teach somebody how to swim, you might not really give to a hoot about how they swim, rather than that they stay up on the surface. The ducks are doing a pretty good job. We want to play with these ducks a lot, but they're getting wet too. They're tired of the rain, kind of like we are. So, function-based definitions, topography-based... Wow! ...are useful in our field. We need to focus on them at all times when we're creating our definitions. So remember, when you're creating your definitions that you're going to work with, you need to make sure it's crystal clear. Describe exactly what you mean, how you mean it. Make sure it's concise. Don't get over-flowering and focus on the function, and if you need to, focus on the topography as well. I think that's enough on defining behaviors. There's more to it. You can look it up in another place, or just go look at some of our other videos. I'm sure we talk about it there too, maybe not in the rain.