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.

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.

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.

And usually I'm not watching the screen. I'm kind of sitting and looking off to the side, spying on people to see what they react to' cause it's - as Joe Ranft used to say, you know, animation is like telling a joke and waiting for three years to see if anyone laughs

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 .

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.

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.