How does MIT tell if a student will "contribute to the community"?

As with any school, great test scores and GPA hardly weigh as much as being an MIT applicant with a lot of personality who will contribute to the student culture. Obviously there’s no “model” student in terms of this, and even if there was, as a high school senior, I couldn’t do much to shift my image in that direction at this point.

I’m just asking out of plain curiosity: what are examples of EC’s that look good to MIT? what do they look for in essays? I know they like to see that you have something you are passionate about, but isn’t every high school student passionate about at least one activity?

Basically: what makes a personality stand out among a pool of applicants, the same way that people believe that a 1600 SAT score will stand out in a sea of 1400’s?

http://mitadmissions.org/apply/process/selection
http://mitadmissions.org/apply/process/match