# Robotic Motion Learning Framework to Promote Social Engagement
## 1 Introduction
### Imitation in Robots  
Human-robot interaction (HRI) may serve as a \"bridge\" in social interaction for people with neurological disorders. Robotic therapy continues to grow with interest as a viable method for increasing social engagement skills in children with ASD. Studies have shown that children with ASD find robots to be more approachable than human strangers [4]. Additionally, children paired with robot mediators in therapy showed an increase in shared attention and facial expression imitation of the mediator, in comparison to children paired with a human mediator [4]. Overall, research suggests that children with ASD find robots more interesting and engaging than human therapists, improving interaction in therapy sessions [5].  
Neurotypical children enjoy interacting with robots as well, provided that the robot's behavior stays within parameters similar to standard human-human interaction. Users prefer robots to stand at a moderate distance (at a \"social\" distance, versus \"personal\" or \"intimate\"), provide moderate eye contact, and not wait an extended period of time to respond to the user [6]. Finally, people prefer interacting with a robot that appears to provide adaptive and intelligent responses [7].  
Evidence of humans displaying the Chameleon Effect toward robots has been documented in multiple studies. In [8], participants were paired with either a human or robot demonstrator. The user was asked to copy the demonstrator and relocate their empty hand or a held object to the matching end position. The manner in which they reached the end goal was not specified. However, the results showed that the participant tended to imitate the trajectory and velocity with which the demonstrator reached the end goal, indicating motor contagion. In [9], participants were asked to use a Nintendo Wii remote to mime gestures simultaneously with a robot. Participants noted feeling \"more comfortable\" while completing the task when the robot matched their gesture speed, rather than moving at its preset pace. Change in the robot's motor behavior to match the user's speed invoked an empathetic Chameleon Effect response and improved the participants' overall perception of the robot. In [2], users played a pose imitation game with NAO, a small humanoid robot made by Softbank Robotics (initially designed at Aldebaran Robotics). NAO robot demonstrated increasingly complex gestures with either a positive or negative mood. The researchers found that, during the easy version of the game, users were likely to display mood contagion and match the robot's demeanor along with the poses. These studies indicate that robotic imitation encourages humans to perceive robots as equivalent social agents when working together in a goal-oriented setting.  
This research aims to determine the effect of robotic imitation on participant behavior during a structured social setting, rather than a goal-oriented setting. In this study, participants engage in a two-part game with ROBOTIS-OP2, a small, humanoid robot. The participant and robot take turns demonstrating unique gestures, but unlike the above studies, the two agents do not work together to complete an official task. The experimenter aims to determine whether robotic imitation will elicit increased user engagement during a 1:1 human-robot social interaction, instead of the human and robot completing a physical, task-oriented interaction.