Blinking into Emotion: How Context and LED Frequency Shape Non-Humanoid Robots’ Emotional Transparency

Abstract

In social contexts, correctly interpreting communicative signals is essential for understanding an interlocutor’s reactions. Emotional cues provide important context, enhancing mutual understanding and enabling more natural, adaptive interactions. For non-humanoid robots, which typically have more limited interaction capabilities, it could be necessary to combine multiple non-verbal signals and to consider the context in which they are used. In this work, we present the design of non-verbal behaviors that enable a non-humanoid robot to communicate its intended emotional state effectively. Our strategy focuses on the use of LEDs as non-verbal cues along with facial expressions for conveying emotions. We conducted a user study to evaluate the effect of these channels with and without context. Our results show that the robot conveys emotions more transparently when context is included, and that blinking LEDs can be an effective channel for communicating emotion. Results suggest that blinking alone is a minimal but functional cue, with richer models performing better without context. When short contextual sentences and more spaced blink frequencies are added, the blinking-only condition performs on par with, or even better than, the full multimodal model for some emotions and, in particular, with respect to participants’ perceived arousal. This indicates that carefully designed, simple visual cues can be an effective affect channel for non-humanoid robots.