The second study was similar, but researchers gauged perceptions by providing subjects with personality profiles of made-up colleagues.

CNN: Study: Neurotics shine over time in team settings

If Gerbrandt's endorsement of NBC 's success sounds cynical, that's only because previous Olympic Games broadcasts, most notably NBC's carriage of the Sydney games, were botched by lengthy personality profiles that sent TV audiences running in the opposite direction.

FORBES: Olympics Ratings Won't Stick

Researchers looked at the Facebook profiles and likes, along with surveys and personality tests, for 58, 466 individuals.

CNN: Heather Kelly,

As with LinkedIn, dating-site profiles are constructed specifically to show one side of a personality.

CNN: Review: Facebook's Graph Search is not very useful

Chemistry.com, for instance, promises to match people based on their neurochemical profiles, while eHarmony.com attempts to measure applicants on 29 dimensions of personality.

WSJ: Jonah Lehrer on Eharmony.com, Chemistry.com and Other Dating Services | Head Case