In Sync: Exploring Synchronization to Increase Trust Between Humans and Non-humanoid Robots

Title of the Paper

In Sync: Exploring Synchronization to Increase Trust Between Humans and Non-humanoid Robots

Paper Information

• Field of Study: Human-Robot Interaction (HRI)
• Keywords: Synchronization, Trust, Non-humanoid Robots, Dynamic Approach, Design Strategies

Research Background and Problem

• Identified Problem or Challenge: Current research and design strategies predominantly focus on humanoid robots, aiming to enhance user trust by making robots more expressive or human-like. However, these strategies are limited in the context of simple non-humanoid robots (SNHRs) and may lead to user confusion and frustration due to unrealistic expectations. Additionally, there is a lack of methods specifically designed to build trust in non-humanoid robots.
• Significance: As robots become increasingly integrated into daily life, establishing and maintaining user trust in robots has become a critical issue in the field of human-robot interaction. Trust is a key factor in determining the adoption of robots in everyday life, influencing users' reliance on robots, delegation of tasks, and acceptance of their suggestions.
• Research Motivation and Related Work: This study draws on the theoretical foundation of synchronization effects in social psychology and neuropsychology, proposing that physical motion synchronization with humans can enhance trust in robots. This synchronization does not require robots to possess complex interaction capabilities or human-like appearances. Previous research has demonstrated the significant role of synchronization in fostering interpersonal trust, but similar exploration in the domain of non-humanoid robots remains absent.

Proposed Solution

• Proposed Solution:
  • Designed a prototype of a simple non-humanoid robot (SNHR) capable of physical motion synchronization.
  • Enhanced human users' trust in robots through synchronized movements.
• Innovative Contributions:
  • Applied social synchronization theory to robot design, proposing a novel strategy to enhance trust, particularly for simple non-humanoid robots.
  • Challenged the traditional approach of relying on humanoid appearances and human-like interaction capabilities to build trust, focusing instead on the role of dynamic behavior.
• Implementation Steps:
  • Prototype Design and Manufacturing: Developed a simple single-segment continuum robot with a flexible vertical bending structure driven by cables. Sensors were designed to track human upper-body movements, enabling the robot to perform synchronized motions based on the data.
  • Testing Three Motion Modes: Fully synchronized motion, random motion, and simple repetitive motion.
  • Experimental Design: Participants freely interacted with the robot, completed a trust questionnaire, and decided whether to participate in a coin-based "trust game."

Research Findings

• Specific Findings:

  • Synchronized motion significantly increased participants' trust in the robotic device (measured via a questionnaire). Compared to random and simple motion modes, synchronized motion scored higher in "reliability," "familiarity," and "integrity," while reducing ratings for "alertness" and "distrust behaviors."
  • In the "trust game," the amount of coins invested was slightly higher in the synchronized motion condition, though the difference was not statistically significant.

• Advantages Compared to Existing Solutions:

  • Does not rely on humanoid appearances or complex interaction capabilities, making it applicable to non-humanoid robot designs.
  • The synchronization strategy is simple, does not require expensive hardware, and enhances harmony and emotional connection.

• Experimental or Evaluation Results:

  • Experiments with 51 participants demonstrated a significant positive impact of synchronized motion on trust scores in the questionnaire.
  • No significant effect of synchronized motion was observed on participants' willingness to spend money in the trust game.

• Limitations and Future Directions:

  • The abstract design avoided interference from form and function, but this may limit the generalizability to real-world task scenarios. Future studies should test the impact of other robot forms and functions on the synchronization strategy.
  • Participants' understanding of the coin-based trust game may have confounded the study's purpose. Experimental design should be optimized, such as integrating the trust game directly into the interaction.
  • Further research could explore extending synchronization signals to other parts of the human body (e.g., breathing or heart rate) or translating synchronization into other output modalities (e.g., light intensity).
  • Ethical risks of the synchronization strategy, such as its potential misuse to deceive target users, should be carefully reviewed and regulated.

Conclusion

This study is the first to explore enhancing human users' trust in non-humanoid robots through motion synchronization, proposing a forward-looking dynamic design strategy. Although some results from the "trust game" were not statistically significant, this research provides a new perspective on dynamic behavior as a design focus and lays the foundation for future design practices and theoretical studies in human-robot interaction systems.