A multi-character display method for enhancing persuasion in a single robot

Service and communication robots are increasingly engaging users in persuasive dialogue – such as everyday choices between study modes, shopping channels, or media platforms – where influence often originates from multiple sources. However, deploying multiple robots is costly and space constrained, and on-screen agents lack the embodied presence of physical robots. We investigated Character Multiplexing (multiplexing), a speaker configuration where a single embodied robot presents multiple viewpoints by rapidly switching its on-head display face and synthesizing distinct voice to represent different characters (Teleco). In a lab within-subject study (N = 31), the participants discussed three everyday topics with the robot under three speaker configurations: single (one character on one robot), multiparty (three robots, one character each), and multiplexing (one robot switching among three characters). Multiplexing increased perceived speaker multiplicity and perceived pressure and produced a larger attitude shift (Δ Attitude) than single, whereas multiparty did not exceed single on pressure or persuasion. Additional analyzes demonstrated that multiplexing was perceived as involving more speakers than multiple parties, indicating that staging viewpoints as sequential, character-switched utterances from the same body can amplify the perceived multiplicity and pressure without adding hardware. Conceptually, a single robot can embody multiple personas. Practically, multiplexing offers a low-cost, space-efficient path to stronger, user-respectful, and persuasive dialogue. Future work will orthogonally vary explicit role relationships (e.g. expert-layperson; pro-con), compare their effects on persuasion and pressure, and establish ethical safeguards to prevent undue stress and manipulation.