Automated driving eliminates the need for human drivers as interaction partners. External human-machine interfaces (eHMI) can serve as a new communication interface between automated and manual vehicles. This study investigates how factors relating to prosocial behavior can be integrated into the design of an eHMI. Based on previous research findings, a visual eHMI according to DIN 9421–125 was designed and evaluated in interviews (n = 8). The results show that positive emotions were promoted by ‘thank-you’ gestures of an avatar. However, the colour design based on the traffic light scheme led to confusion. The study indicates that eHMI can promote prosocial behavior in road traffic and provides an initial starting point for further research.