Supplemental Material for Children’s reciprocity and relationship formation with a robot across age.

Abstract

Reciprocity is central to the formation and maintenance of relationships. Reciprocity and relationship formation change with children's development and are key aspects in human-robot interaction. So far, it is unclear how children reciprocate and build a relationship with a social robot and how this reciprocity develops with age. In the present study, we collected data from 147 children aged 5-12 years to investigate age differences in reciprocity and relationship formation toward a social robot. To test reciprocity, children completed an Alternated Repeated Ultimatum Game with a social robot and another child. Children also completed a survey on relationship formation to assess robot-related closeness, trust, and social support. Results from a linear-mixed effects Bayesian analysis indicated that children reciprocated similarly to a robot as to another child. While reciprocity differed across age with lower values for 8-10-year-olds compared to younger and older children, these age differences in reciprocity were also observed when children interacted with the robot. Children's relationship formation with a social robot also changed with age. Our findings suggest that established theories from human-human literature (e.g., age differences in reciprocity) are also relevant for human-robot interaction. Children's age is an important determinant for how children interact with and perceive robots.