Multimodal prompts effectively elicit robot-initiated social touch interactions

Social touch plays an important role in building interpersonal relationships and might therefore also facilitate interactions with social robots. As people tend to have less experience interacting with social robots compared to with humans, especially with interactions involving social touch, more explicit communication might be necessary to disambiguate social intentions. In the experiment, participants engaged in an informal conversation with humanoid robot Pepper. Throughout the interaction, Pepper initiated various social touch interactions such as a handshake during introductions and a hug to say goodbye by using either a unimodal prompt (control condition: movement cue only) or a multimodal prompt (experimental condition: movement and verbal cue). The results show that the multimodal prompts significantly increased the number of successfully elicited social touch interactions. No significant differences in the self-reported perception of the robot were found between condition. Our results help to inform the design of robots that are intended to engage in social touch interactions.