One of the tests asks the user to follow a moving finger with their mouse. If they fall outside the circle they are locked out of Facebook

The Social Media Sobriety Test lets the user choose which web applications they want to be tested on before they can access them. They can also set the time when the test comes into effect

Source: http://www.dailymail.co.uk/sciencetech/article-1328739/Facebook-gets-Soc...