How did we get here? Scientists now say that just seeing the Facebook logo is enough to get some people craving time online. Pavlov's dog better start barking!

Dutch researchers studied the online habits of 200 people, and found that showing frequent Facebook users the site's logo sparked pleasurable thoughts in the brain.

The Daily Mail quotes study leaders as saying, " results support our hypothesis that exposure to social media cues (like a logo)  triggers spontaneous hedonic(pleasurable) reactions in frequent social media users." (Daily Mail)