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.

Yeah, to bring families together I need to go away.

I mean, I've - these other films were flukes. I don't know what I'm doing. I should just quit. What would I miss? I'd miss my house and I'd miss going to work. But I think the thing that I realized I would miss most is probably similar to everybody, which is your friends.

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.

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 .

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 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.