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.

Anger is about fairness. If it feels that you're getting ripped off or taken advantage of, that's when anger comes up. Sadness deals with loss. And I suddenly had this new revelation - it felt like to me - that those are all true, but the real, deeper reason we have emotions is to connect us together. And that felt big to me.

Well, what if we did this in the mind as opposed to the brain? So instead of blood vessels and dendrites, what if it was consciousness and dream production? And that would allow us to have characters that represent emotions. And that felt like, man, that's exactly what animation does best - strong, opinionated, caricatured personalities. And that just got me excited.

And as I was sort of doodling, I was thinking, surprise and fear - probably fairly similar so let's just lose surprise. And that left us with five.

The way real memories work, from what we understand, is really complex. And it's an interconnection of different things and redundancy in the brain. So the idea of a memory existing as a little snow globe - the way we represent it in the film - is actually not scientifically accurate at all.

I'm not actually sure if guilt is an emotion. In fact, that was - at the very beginning of this process, we realized, man, we really don't know very much about this subject so we better do some research. And we started looking around online.

However, for story reasons, we needed to represent them in certain ways. One of the things that sort of blew me away that I didn't know when we started is that memories are completely susceptible to change. And this is, you know, one of the many reasons why certain people are trying to get it taken out - eyewitness testimony in court cases because it's very unreliable.