A year ago there was a study conducted on that topic: http://www.sciencemag.org/content/333/6043/776.abstract http://www.sciencemag.org/content/333/6043/776.abs

A year ago there was a study conducted on that topic: http://www.sciencemag.org/content/333/6043/776.abstract http://www.sciencemag.org/content/333/6043/776.abstract It's behind a paywall, but you can read a number of commentaries, e.g.: http://news.columbia.edu/googlememory http://news.columbia.edu/googlememory