Emotional Expression in Low-Degrees-of-Freedom Robots: Assessing Perception with Reachy Mini

TL;DR

This study investigates how people perceive and interpret emotional expressions on a low-DoF robot, Reachy Mini, revealing that even limited expressions can convey affect and influence social impressions.

Contribution

It provides empirical insights into affective communication and perception in low-DoF robots, highlighting their potential for social interaction research.

Findings

Exact emotion recognition was modest and varied across expressions.

Participants better identified broader affective dimensions like valence and arousal.

Positive expressions increased perceptions of warmth and sociability.

Abstract

Emotion expression is central to human--robot interaction, yet little is known about how people interpret affect on robots with sparse, non-anthropomorphic expressive capabilities. This study examined how people perceive emotional expressions displayed by Reachy Mini (Pollen Robotics and Hugging Face), a low-degree-of-freedom (low-DoF) robot with a constrained and distinctly non-human expressive repertoire. In an online within-subjects study, 100 participants viewed 10 short video clips of Reachy Mini expressing different emotions and, for each clip, identified the perceived emotion, rated its valence and arousal, and evaluated the robot on social-perception traits. Exact emotion recognition was modest overall and varied considerably across expressions, with anger, sadness, and interest recognized more reliably than emotions such as love, pleasure, shame, and disgust. However, participants were generally more successful at recovering broader affective meaning than exact emotion labels, particularly along valence and arousal dimensions. Emotional expressions also shaped social evaluation, as positive expressions were perceived as warmer and more sociable than negative ones, and animacy varied less across conditions. These findings suggest that even constrained robotic expressions can communicate affective meaning and influence social impressions, positioning Reachy Mini as a useful benchmark for studying affective communication in low-DoF robots.