It's very important to have good assent and consent procedures, and we're very careful in going over consent forms with parents and explaining it. And with the child, they all sign assent forms which means now we have some forms that are in their language, and we go over them at the age-appropriate level.

And we basically just tell them what's going to be happening and that they can stop at any time. It's totally, it's up to them. They're volunteering, they don't have to do this, and no one's going to be mad at them if they don't, and you're not going get a bad grade, and it's just that they're helping us. And here's what might could happen. You could be a little scared in the scanner, you're going to get a little blood drawn, or saliva sample, or something.

And of course, they can balk. And depending on where you are — in our area, kids are very opinionated. And from nine on they can make decisions. And so they're very good about asking questions and talking about it. But most of the time, we explain things pretty thoroughly, so it's not a problem.