Abstract

Background As countries around the world rapidly enter aging societies, elderly users’ need for emotional care has increased significantly. Prior research on care robots has focused primarily on physical assistance functions, but the effect of robots’ multimodal interactions on the formation of elderly users’ perceived intimacy has not yet been fully clarified. This study aimed to analyze how care robots enhance the emotional bond of perceived intimacy with elderly users by employing three interaction modes: facial expression, dialogue, and behavioral responses.

Methods A 1:1 interaction experiment with the Enabot EBO X care robot was conducted with 175 elderly users aged 60 and above residing in eastern China. Participants were randomly assigned to four groups based on the activation status of the three interaction modes: facial expression, dialogue, and behavioral responses. After each session, a structured questionnaire measured six subdimensions of perceived intimacy (familiarity, warmth, connectedness, physical accessibility, belonging, and sharedness). Statistical analysis was conducted using multivariate analysis of variance.

Results Individual characteristics of elderly users—such as age, health status, gait independence, and experience with digital devices—showed significant differences in overall perceived intimacy. Although there were no statistically significant differences in overall intimacy scores among the three interaction modes, at the subdimension level, behavior-centered interaction elicited higher familiarity than dialogue-centered interaction.

Conclusion This study suggests that behavioral elements are effective for initial familiarity formation when designing multimodal interactions for care robots. It also confirmed that interfaces enhancing physical accessibility and shared experiences are key to strengthening the emotional bond with elderly users. Future care robots should prioritize the enhancement of perceived intimacy through multimodal functionalities that align with user expectations.

Keywords Elderly Care Robot, Perceived Intimacy, Acceptance Intention, Multimodal Interaction Interface, Technology Acceptance Model (TAM)