Mood indicators or mood badges were devices worn on one's back that expressed a person's mood.
They were made so the user could never see their own mood, and as soon as they put it on, it would travel to the back of the user. They were used to show the Emojibots how the person was feeling, and if they were "too sad to live", the Emojibots would kill the person. However, they were originally used to indicate satisfaction, as the purpose of the Vardy were to keep the inhabitants of the city happy. The mood badges had various emojis for different states of minds, such as thinking, being happy, angry or sad. This concept was very similar to the Emojibots, as they too change depending on what people say, do, or what the badges indicate. (TV: Smile)