What you 'like' on Facebook can be revealing

A sign with Facebook's "Like" logo is posted at Facebook headquarters near the office for the company's User Operations Safety Team in Menlo Park, Calif. in this Dec. 13, 2011 file photo. A study by researchers at Cambridge, published today in the Proceedings of National Academy of Sciences, has found that clicking the social network's friendly blue "like" buttons may reveal more about people than they realize.