But the truth is, at some point, our films - almost every single one of them - are really bad. And it's largely hats off to John Lasseter and Ed Catmull who have set up a system whereby they're expecting it.

And it sort of hit me that the very subject matter of the film that I'm dealing with is the key to the most important thing in our lives, and that's our relationships. And so we had done all this research showing the job of each individual emotion, you know, fear keeps you safe. It deals with uncertainty.

They're expecting us to make mistakes, and they've set up a process that allows us to correct for that and do it again and iterate. So I think that's a real key to the films that we've made.

My father was working on his Ph.D. on Danish choral music - the Danish choral music of Carl Nielsen - so over there to do research.

We found some scientists think that there are basically three emotions. Others went up to 27. Others had 16. Some were in the middle. So we were kind of left with no definitive answer to our basic question - how many are there?

Well, the film initially - we had decided to pair joy with fear because I don't know about you - for me fear was a major motivator in junior high. So we thought there's probably some good stuff there... As the film went on, we had developed all these great scenes that were really funny, but in the third act, it wasn't adding up to anything.

If you were feeling sad right now and you recall a sad - or, a very happy memory from the past, it will be tinged with more sadness based on your current feeling. So we felt like that was actually on solid scientific ground .