 Trials to criterion. It's a method of recording, of event recording, where you record the number of responses it takes to achieve a predetermined level of proficiency or mastery, right? So how many trials did it take for you to learn what you needed to learn in order to get it right? A beautiful example is how many takes this video took? One, two, three, four, five, six, seven. How many trials to criterion? Criterion meaning it made sense. It was in less than a minute. We have a definition and we have an example, right? So there was our criterion. So how many times did it take us to do this? Well, a lot of these believe it or not happen in four or five takes. Some of them happen in one, some of them happen in two, some of them happen in none. I'll let you figure that one out. But, so time to criterion, right? That's time trial. So time to criterion, how long it takes? Trials to criterion, sorry. So how many times, how many attempts does it take to engage in the action at the level that you're desiring?