Leave it to science to explain why teens are so obsessed with social media. University of California researchers scanned teenagers’ brains while they used Snapchat and Instagram and found the part of the brain associated with rewards kicks into overdrive whenever teens see one of their photos earn a lot of ‘likes’. They asked the teens to submit 40 photos from their own personal Instagram accounts to be part of the feed, and then showed them 148 photos from the submissions on a computer screen. The were told the photo stream had already been reviewed by 50 other teens as part of the study, and the photos had earned “likes” from the other teens.(The researchers themselves had assigned “likes” to these photos).