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.

The drive of the story is sort of hinted at the beginning, is Joy and Sadness and those two characters. Especially Joy starting to understand that there's more to life than being happy. And so that's based on real life observations and things that we've learned as adults.

It is one of those weird social things. Even as parents we say, oh, don't be sad. You know, come here, we'll distract you with some ice cream or something. And I don't know if that's always the best thing. But it's certainly - you understand why people do it.

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?

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.

It might have been introduced slowly over the course of the years as you recall this memory over and over. So that was a very cool but complex idea that we thought about representing in the film but could not find a way to make it work.