Dr. Paul Ekman, who worked in San Francisco - still does - which is where Pixar Animation Studios is, he had early in his career identified six. That felt like a nice, manageable number of guys to design and write for. It was anger, fear, sadness, disgust, joy and surprise.

Well, what we do is we have a script, of course. But for us, writing is also like storyboarding. It's drawing. And so we will cut all of those drawings together with music, sound effects and dialogue. And we screen this kind of stick-figure version of the film.

I knew that there was an upcoming screening where not only were we going to show it to everybody else at the studio, we also needed to move into production... And yet I was sitting there in editorial going this is not working. I'm a failure.

A lot of the issues I faced in junior high was what got me into animation. It was easier to sit on the side and draw cartoons than to engage with people.

And in part that's good but then, like any emotion - and this is something we learned from the research as well - there are positive and negative aspects to all of these.

Toy Story we found, sorta by accident, because we didnt know what we were doing, the idea of being replaced by somebody. Everybody has that fear, or encounters this jealousy at some point.

Yeah, we were looking for a way to represent adulthood and the passing into adulthood. And I think, for me personally and a lot of the folks that I work with, childhood is kind of a sacred, special kind of point in time that has a real joy and purity to it. And we sort of long on a daily basis to reach back and kind of grab onto that in some way.