Answer: Co-actor
Step-by-step explanation:
Co-actor, in terms of social facilitation is the person who performs the same activity or action along with the performer.This mechanism is not performed in competitive manner.Performers tends to improve his performance while in presence of audience and co-actor.
According to the question,the guy is known as co-actor in terms of social facilitation as he is performing the same act of sitting along with the person.Thus,this impacts behavior of person as a performer.