UC Berkeley professor breaks down the science of ‘Inside Out 2’

There’s a scene in Pixar’s hit film Inside Out 2 when teen Riley, the human protagonist of the Inside Out world, senses that one of her 13-year-old friends isn’t telling her everything. The audience zooms in to Riley’s mind, where her emotions are trying to figure it all out. Disgust is on top of it. She pulls up a screen and starts examining Riley’s friend’s furrowed brow. “Enhance,” Disgust barks, as the view pushes into the telltale corrugator muscle that controls our eyebrows.

That scene, UC Berkeley psychology professor Dacher Keltner said, is very rooted in science. He would know: he’s been working with Pixar as a scientific advisor on the Inside Out films for over a decade.

“I feel like they are playing a joke on what I’ve been talking to them about for the past 14 years,” he said in this episode of UC Berkeley’s Academic Review video series. “I gave them tutorials on the facial musculature; there are 30 muscles underneath the skin that combine in different ways to express emotion.” 

Keltner spent much of his early career cataloging and analyzing how emotions, particularly embarrassment, play out across our faces. That the film has an inside joke about this sort of real research is perhaps not surprising. Inside Out and Inside Out 2 are, after all, about the emotions that govern our feelings and behavior, and there are many nods to the advances in understanding we’ve gained in mental health, emotions and mindfulness.

In this video, Keltner, who has been teaching students about human emotions at UC Berkeley for over 25 years and co-directs the university’s Greater Good Science Center, unpacks the real science behind the Disgust microexpression scene and new characters in the films.

We may have him to thank for all of the new emotional characters who join the original five in Inside Out 2: Anxiety, Envy, Ennui, and Embarrassment. When Keltner first talked with Pete Docter, the director of Inside Out, he explained that there are 25 emotions that scientists like him have cataloged. Docter, in turn, explained that you can’t possibly have 25 main characters in a film, yet the count is now up to nine as Riley’s emotions expand in her teen years.

Watch to learn more about how scientific research led Pixar to cast Joy as the main emotional character of the first film and why Anxiety is the driving character and emotional force of Inside Out 2 now that Riley is a teen.

Click here to watch a previous Academic Review video about the origins and stories behind national anthems, analyzing deepfakes, and the linguistics of Kamala Harris.