(Image from http://watfordhypno.co.uk/wp/shyness/)
Introverts also are not anti-social because they also interact with others but lesser in frequency than extroverts. The collaboration is more on quality than quantity.
Reference
Baldasaro, T. (2012, September 10). Embracing Introversion: Ways to Stimulate Reserved Students in the Classroom. [Web log comment]. Retrieved from http://www.edutopia.org/blog/introverted-students-in-classroom-tony-baldasaro