  The social acceptance of AI agents, including intelligent virtual agents and
physical robots, is becoming more important for the integration of AI into
human society. Although the agents used in human society share various tasks
with humans, their cooperation may frequently reduce the task performance. One
way to improve the relationship between humans and AI agents is to have humans
empathize with the agents. By empathizing, humans feel positively and kindly
toward agents, which makes it easier to accept them. In this study, we focus on
tasks in which humans and agents have various interactions together, and we
investigate the properties of agents that significantly influence human empathy
toward the agents. To investigate the effects of task content, difficulty, task
completion, and an agent's expression on human empathy, two experiments were
conducted. The results of the two experiments showed that human empathy toward
the agent was difficult to maintain with only task factors, and that the
agent's expression was able to maintain human empathy. In addition, a higher
task difficulty reduced the decrease in human empathy, regardless of task
content. These results demonstrate that an AI agent's properties play an
important role in helping humans accept them.
