随着虚拟现实、元宇宙、生成式人工智能等自然人机交互技术的发展，以交互式虚拟内容为主的人机界面正在给用户提供一种新型的任务挑战——情感挑战。情感挑战主要考察人对虚拟世界情感的理解、探索和处理能力，是元宇宙虚拟交互场景承载的核心内容，也是未来数字世界不可或缺的重要元素。情感挑战自2015年被提出以来，一直受到人机交互领域高度关注。在此背景下，国内外研究者们围绕情感挑战的定义和特性、交互设计、评估量表和计算建模等方面开展了一系列研究工作，本文主要对这些工作进行系统化整理和介绍，并对情感挑战在元宇宙中的应用前景进行展望。首先，本文从传统数字游戏中物理挑战和认知挑战出发，介绍情感挑战的发现、提出、完善和应用；其次，本文对虚拟现实中的情感挑战交互效应研究和情感挑战计算建模方法进行了介绍；然后，本文基于已有工作，从人机交互的角度给出了情感挑战的定义，介绍了情感挑战存在的主要媒介和设计方法；最后，本文总结了情感挑战在元宇宙中的研究意义，并对情感挑战在元宇宙中的应用前景进行了展望。

With the development of natural human-computer interaction technologies such as Virtual Reality, Metaverse, and Artificial Intelligence Generated Content, human-computer interfaces based on interactive virtual contents are providing users with a new kind of task challenge - emotional challenge. Emotional challenge mainly examines the user’s ability to understand, explore and deal with emotional issues in a virtual world. It is considered a core aspect of virtual interactive scenarios in the metaverse and an essential element in the future digital world. Moreover, users’ perceived emotional challenge has been proved to be a serious, profound, and reflective new type of user experience. Specifically, by resolving the tension within the narrative, identifying with virtual characters, and exploring emotional ambiguities, players encountering emotional challenge would be put in a more reflective state of mind and experience more diverse, impactful, and complex emotional experiences. Since the introduction of emotional challenge in 2015, it has attracted significant attention in the field of human-computer interaction. With this background, researchers have conducted a series of research work on emotional challenge with respect to its definition, characteristics, interactive design, evaluation scales, and computational modeling, etc. This paper aims to systematically organize and introduce the related works of emotional challenge first and then elaborate its prospective applications in the metaverse. This paper starts by introducing the concept of challenge in digital games. Game challenge deals with the obstacles that players must overcome and the tasks which they must perform to make game progress. Generally, there are three different kinds of game challenges. Physical challenge depends on players’ skills such as speed, accuracy, endurance, dexterity and strength and cognitive challenge requires players to use their cognitive abilities such as memory, observation, reasoning, planning, and problem solving. Emotional challenge, on the other hand, deals with tension within the narrative or difficult material presented in the game and can only be overcome with a cognitive and affective effort from the player. After that, this paper introduces related works on emotional challenge including how it differs from more traditional types of challenge, the diverse and relative negative emotional responses it evokes, the required game design characteristics, as well as the psychological theories relate to emotional challenge. This paper then introduces how emotional challenge affects player experience when separately from or jointly with traditional challenge in VR and PC conditions. It was found that relatively exclusive emotional challenge induced a wider range of different emotions in both VR and PC conditions, while the adding of emotional challenge broadened emotional responses only in VR condition. VR could also enhance players’ perceived experiences of emotional response, appreciation, immersion, and presence. This paper also reviewed the latest work on the potential of detecting perceived emotional challenge from physiological signals. Researchers collected physiological responses from a group of players who engaged in three typical game scenarios coving an entire spectrum of different game challenges. By collecting perceived challenge ratings from players and extracting basic physiological features, researchers applied multiple machine learning methods and metrics to detect challenge experiences. Results show that most methods achieved a challenge detection accuracy of around 80%. Although emotional challenge has attracted significant attention in the field of human-computer interaction, it has not been clearly defined at present. Additionally, current research on emotional challenge is primarily limited to the area of digital games. We believe that the concept of emotional challenge has the potential for application in various domains of human-computer interaction. Therefore, building upon previous works on emotional challenge, this paper provides a definition and description of emotional challenge from the perspective of human-computer interaction. Emotional challenge primarily examines users" understanding, exploration, and processing abilities of emotions in virtual scenarios and the digital world. It often requires individuals to engage in meaningful choices and interactions within virtual interactive environments, as they navigate emotional dilemmas and respond to the uncertainties arising from their interactions. For instance, in a virtual scenario, a sniper aims at an enemy soldier holding a rocket launcher, intending to destroy their own camp. However, the sniper suddenly realizes that the enemy soldier is a close friend with whom they have shared hardships. When faced with the decision of whether to pull the trigger, the sniper may experience an emotional challenge of "agonizing between friendship and protecting their own base." With the proposed definition of emotional challenge, we also elaborate on how emotional challenge is understood from the perspectives of users and designers and highlight the main mediums through which emotional challenge exists. Finally, this paper summarizes the research significance of emotional challenge in the metaverse and provides an outlook on the application prospects of emotional challenge in the metaverse. The metaverse aims to create a comprehensive virtual digital living space that maps or transcends the real world. It will include a plethora of virtual content and virtual characters, with users being a part of it and interacting with these virtual characters or content. Through autonomous interactions with the virtual characters or content, users are likely to explore complex emotions and confront with emotional challenge. Hence, emotional challenge will be the core content embedded in virtual interactive scenarios within the metaverse, making it an essential element in the future digital world. In the design of metaverse systems for application, the involvement of emotional challenge can equip the metaverse with the ability to evoke and generate complex but meaningful emotional experiences. It can assist in training users" skills in understanding, exploring, and dealing with difficult emotional issues, promoting self-realization, self-expression, and self-management abilities and thus building correct life outlook and values.