Effect of number of robots on perceived persuasion and competence

Persuasive robotics has gained immense traction over the years, due to its potential to be used as a behavioral change system and to influence decision making in humans. With a plethora of existing studies in the field, this paper adds to the sea of knowledge by exploring the effect of number of robots on perceived persuasion and competence of a robot by revisiting Human-human Interaction theories of ‘multiple-source effect’ and ‘message reinforcement’. A simple two condition (one vs two robots) between-subjects experiment was conducted across two stages, and human participants engaged in a persuasive dialog-based interaction with the robot(s) Pepper and NAO where participants choose between two drink options and complete a survey. The results reveal a single robot is more persuasive and competent than multiple robots. Further analysis of qualitative data provides insights about the effect of robot morphology, social influence, familiarity with technology and intergroup dynamics, all of which collectively impact human perceptions and reactions. The implications of this research showcase the purposeful use of robots for marketing or brand promotion and further encourage better strategies of natural robot-robot & human-robot interactions.