Emotional clouds: Showing arousal and valence through the movement and darkness of digital cartoonish clouds

• We visualize arousal and valence through the movement and degree of darkness of a series of cartoonish clouds.
• Movement and darkness are correctly interpreted as arousal and valence respectively.
• Changes of valence and/or arousal are adequately perceived by users.

While nowadays the most usual way to show emotions in digital contexts is via virtual characters, its use may raise false expectations (the user attributes human abilities to the virtual character). This paper proposes and explores an approach to express emotions which intends to minimize the user's expectations by using a non-anthropomorphic model. Emotions are represented in terms of arousal and valence dimensions. They are visualized in a simple way through the behaviour and appearance of a series of cartoonish clouds. In particular, the arousal value is expressed through the movement of these clouds (controlled by a flocking algorithm), while the valence value is expressed through their degree of darkness. Furthermore, the paper describes a user experiment which investigated whether the arousal and valence expressed by our model are appropriately interpreted by the users or not. The results suggest that movement and darkness are interpreted as arousal and valence respectively and that they are independent of each other.