Providing a robot with the capabilities of understanding and effectively adapting its behaviour based on human mental states is a critical challenge in Human–Robot Interaction, since it can significantly improve the quality of interaction between humans and robots. In this work, we investigate whether considering human mental states in the decision-making process of a robot improves the transparency of its behaviours and mitigates potential human’s false beliefs about the environment during collaborative scenarios. We used Bayesian inference within a Hierarchical Reinforcement Learning algorithm to include human desires and beliefs into the decision-making processes of the robot, and to monitor the robot’s decisions. This approach, which we refer to as Hierarchical Bayesian Theory of Mind, represents an upgraded version of the initial Bayesian Theory of Mind, a probabilistic model capable of reasoning about a rational agent’s actions. The model enabled us to track the mental states of a human observer, even when the observer held false beliefs, thereby benefiting the collaboration in a multi-goal task and the interaction with the robot. In addition to a qualitative evaluation, we conducted a between-subjects study (110 participants) to evaluate the robot’s perceived Theory of Mind and its effects on transparency and false beliefs in different settings. Results indicate that a robot which considers human desires and beliefs increases its transparency and reduces misunderstandings. These findings show the importance of endowing Theory of Mind capabilities in robots and demonstrate how these skills can enhance their behaviours, particularly in human–robot collaboration, paving the way for more effective robotic applications.

As hybrid interactions between humans and artificial agents become more prevalent, social skills are increasingly essential for autonomous systems. Beyond assisting in various tasks, robots are expected to understand human states and recognize that knowledge and perceptions of the world can differ, influencing overall behavior. This ability is closely tied to motivation, which plays a crucial role in driving autonomous agents’ actions. In this work, we explore the interaction between two intrinsically motivated cognitive autonomous robots with distinct profiles and preferences, utilizing Theory of Mind to infer each other’s motivations. We investigate the conditions under which they successfully collaborate to achieve mutual well-being and the circumstances that hinder cooperation. Our findings indicate that successful interactions emerge when at least one agent prioritizes helping others and when their profiles are aligned, leading to positive outcomes for both.

For social robots to collaborate effectively, they must infer and correct false human beliefs, especially when misconceptions directly impact task outcomes or pose safety risks to humans. In this work, we investigated whether a robot’s ability to detect and rectify users’ false beliefs improves trust and perceived social competence. In an in-person between-subject study, 98 participants collaborated with a robot to solve a task. Participants interacted with either a robot that actively corrected their false beliefs by using Theory of Mind or one that complied with their incorrect instructions. Contrary to expectations, trust, mental state attribution, and perceived warmth or competence did not differ between groups. The results also showed that human reluctance to trust the robot’s input persisted, suggesting that belief correction alone cannot overcome relational barriers. In addition, the study showed that participants who trusted the robot’s corrections perceived it as more socially attuned.

Social robots are becoming increasingly present in our daily lives and will continue to be integrated into society to help people with their daily routines. In this paper, we create a general motion dictionary for the NAO robot, to generate emotional gestures when the robot is interacting with humans. We implemented the motions in the context of a museum setting, wherein NAO interacts with visitors as a guide. We present a Motion Dictionary which integrates each gesture’s features and the corresponding emotions. By using the Choregraphe simulator to create the motions and validate them with a real robot, we intend to simplify and help with the generation of emotional gestures for human-robot interaction.

In order to achieve a widespread adoption of social robots in the near future, we need to design intelligent systems that are able to autonomously understand our beliefs and preferences. This will pave the foundation for a new generation of robots able to navigate the complexities of human societies. To reach this goal, we look into Theory of Mind (ToM): the cognitive ability to understand other agents’ mental states. In this paper, we rely on a probabilistic ToM model to detect when a human has false beliefs with the purpose of driving the decision-making process of a collaborative robot. In particular, we recreate an established psychology experiment involving the search for a toy that can be secretly displaced by a malicious individual. The results that we have obtained in simulated experiments show that the agent is able to predict human mental states and detect when false beliefs have arisen. We then explored the set-up in a real-world human interaction to assess the feasibility of such an experiment with a humanoid social robot.

Social robots are often critiqued as being too ‘robotic’ and unemotional. For affective human-robot interaction (HRI), robots must detect sentiment and express emotion and empathy in return. We explored the extent to which people can detect emotions, empathy and sentiment from speech expressed by a computer system, with a focus on changes in prosody (pitch, tone, volume) and how people identify sentiment from written text, compared to a sentiment analyzer. 89 participants identified empathy, emotion and sentiment from audio and text embedded in a survey. Empathy and sentiment were best expressed in the audio, while emotions were the most difficult detect (75%, 67% and 42% respectively). We found moderate agreement (70%) between the sentiment identified by the participants and the analyzer. There is potential for computer systems to express affect by using changes in prosody, as well as analyzing text to identify sentiment. This may help to further develop affective capabilities and appropriate responses in social robots, in order to avoid ‘robotic’ interactions. Future research should explore how to better express negative sentiment and emotions, while leveraging multi-modal approaches to HRI.