I think when you are asking a 45 year old to answer a questionnaire like, I am a hard worker, and you ask a 16 year old to answer, but let's take another extreme example,. I gave up the skill at the Green Berets, right. And then I went to the Chicago public schools and gave it up to 16 year-olds. And I just have to imagine that when a Green Beret makes a statement like,I'm a hard worker, that what goes through their mind is different from a 16 year-old kid, right. >> [LAUGH] >> And that's related to your question. Like a 40-year-old versus a 20-year-old, answer the same question. Here's my guess. My guess is that you have an even steeper line here. If you could eliminate, if you can get everyone to have the same frame of reference, you would have even bigger difference maybe between a 40-year-old and a 20-year-old. But I don't have, you have to have a non questionnaire measure, right? >> Right. >> To really get at that. And our lab is been working on other measures. They're trying to actually come up with the next marshmallow test. Right. Can you create a performance measure, not a questionnaire measure? It's so hard. They don't work primarily for the following reason. In the marshmallow test, all the four-year-olds like treats, right? And by the way, you have to ask the four-yea-old what treat, you get like a little buffet of treats, and they get to pick their least favorite treat and then they pick their most favorite treat, and then you take all of the other treats away, now it's just your favorite treats. And so you know that all these four-yea-olds want the treat. And also they're four, so they're not the most complicated creatures. They want candy, even by five or six. And I've run that delayed gratification task with ten-year-olds, they're so much more complicated. They're like, why are you leaving, why can't I come with your? >> [LAUGH] >> Four-year-olds are like okay. >> [LAUGH] >> [INAUDIBLE] and we find that problem with measuring grit, in a performance task with adults. And the primary problem is that, if you're Will Smith and you consider the treadmill to be a test of your will, you're going to stand a treadmill. You put me on the treadmill and I'm like, I'm getting off. Why do I care if I pull this treadmill. So we have a hard time finding a persistence task where everybody equally cares about it, and we haven’t solved it yet.