 In envisaging how the mind 's interior would be depicted , the filmmakers concentrated on the word electrochemical ; Ralph Eggleston , the film 's production designer , explained , " It meant thinking of things as energy or energy @-@ based , excitable . " Each emotion has a glowing , " effervescent quality " to them ( particularly Joy ) , which was difficult to animate as it could be viewed as distracting . " The characters are created with this energy because we are trying to represent what emotions would look like . They are made up of particles that actually move . Instead of being skin and solid , it is a massive collection of energy , " Docter remarked . The team worked for eight months on Joy 's " sparkly " aura , but was prepared to delete it , as it would affect the film 's budget . However , Lasseter requested that it be applied for each emotion . " You could hear the core technical staff just hitting the ground , the budget falling through the roof , " recalled Eggleston . 
