Joy, Sadness, Anger, Fear, and Disgust
We hate to be the ones to break this to you, but your sense of anger isn't a little red dude who dresses like middle management at a box factory and frequently erupts into flames.
Anger, Joy, Sadness, Fear, and Disgust are all symbols of abstract thought. Inside Out serves up anthropomorphized emotions instead of, say, talking blobs.
We're so not into talking blobs.
Each of the characters behind the control panel in Riley's cranium are given recognizable human qualities. These not only make them easier to understand and relate to than talking blobs, glowing auras, or something similarly nebulous, but they also aesthetically reinforce their personalities.
Joy is bright and upbeat, for example, with a youthful, twirling dress and cropped blue hair that your Aunt Karen would describe as "fun." Sadness, meanwhile, is blue from head to toe. She's frumpy, with stick straight hair, massive glasses straight out of 1988, and a fondness for turtlenecks. Her flat voice drips with despondency.
Fear looks like a walking nerve, or perhaps a question mark, as he continually contorts with anxiety and doubt, and Disgust bears a striking resemblance to Riley's least favorite food: broccoli.
Joy and the rest of the gang are all a bit rough around the edges, too. No, we're not piling an idiom on top of a metaphor. We mean they're literally a little fuzzy around the edges.
This aspect of their character design does two things. First, it helps distinguish them from the "real world" or outside world characters in the film, like Riley and her parents. Second, it symbolizes their energy as emotions. They're constantly humming with the power of feelings.