Gloomy

During the interaction, the robot detects a situation that it classifies as conflicting with its own goals. Such situations usually cause negative emotions in humans, which are often made visible through body language. The robot can use similar means to make its internal state visible to the user. This expression is not so much related to an actual negative feeling of the robot (that – as a machine – is not capable of experiencing emotions). Still, it can be used as a way to make the goals and intentions transparent to the user and thus to make it easier for her to anticipate the robot’s future action. In addition, an expression of happiness might be employed as a means for keeping the user entertained.