Inside Out is set inside the mind of an 11-year-old girl whose emotions -- joy, sadness, anger, fear and disgust -- compete to control her.
Getting inside the head of a pre-teen is no easy task, but then Docter relishes unusual challenges.
"I think the secret source to animation, like anything, is truth," says Docter. "So even though we are taking people to these far out places and showing them characters that you'd never believe are alive -- cars, bugs, monsters -- we are seeing something of ourselves on screen.
"It's an opportunity to bring people to somewhere everyone has thought about, but no one's seen before with their eyes, and that's the world inside your head."
The Disney/Pixar film, which will be released on June 17, has already been given rave reviews by Cannes film festival critics.
Indeed, last time Docter premiered a film at Cannes, it went on to gross $700 million at the box office and took home two Oscars.
Docter was the third animator hired by Pixar in 1994, working on the studio's first ever feature film, Toy Story.
Since then he has become renowned for creating movies that not only entertain, but leave viewers with a deeper understanding of what it means to be human.
"People are funny -- they are able to project personality onto anything. I remember as a kid I spent a $5 bill once and felt so bad because the other $5 bill was now going to be lonely without all the other bills I had in my wallet," said Docter.
"You just invest these dead things with life and that is our tendency as people. So animation takes advantage of that, grabs on to it, and runs with it."
How to achieve greatness
So what does it take to be a truly great animator?
"A great animator is basically a great actor. Yes they have the technical skills, they can draw, they can operate a computer. But fundamentally they are thinking about what is going on inside the character's head," said Docter.
"They are always thinking about what is causing that movement so it is not movement for movement's sake."
Docter's One to Watch
As for the next generation of animators, Docter has dubbed Japanese artist, Dice Tsutsumi, as one to watch.
"You look at his paintings and you go 'wow, he captured life in a way that I've never really seen before. It's got this beauty to it, his sense of lighting, the reflection, the warmth in there/ It's beautiful stuff," he said.
This year Tsutsumi's short film, The Dam Keeper, received an Oscar nomination. It tells the story of a baby pig who protects his town from clouds of pollution with a windmill, and on a deeper level explores the dark reality of childhood bullying and the healing power of art and friendship.
Find out more about Tsutsumi and his work on CNN's Ones to Watch.