If you’ve felt a pressing need to check your email account every few minutes – and your social feeds every alternate second – it’s time to stop worrying. There’s a seemingly logical explanation for what drives us to constantly stay connected.

In a video released by Big Think, professor Tim Wu, who teaches at Columbia Law School, explains that it’s almost a biological feeling. It all began, he says, around the 1970s with email.

The first email addict, says Wu, was a man named Stephen Lukasik who was the head of the ARPA agency – the predecessor of the internet – in the Pentagon back then. Lukasik was so obsessed that he’d carry around a heavy portable computer just so he could check his e-mail.

Who’d do that today? No one, right? We have smartphones.

As for the psychology behind this kind of behaviour, Wu posits that the reward is unexpected, which changes everything. There’s plenty of dull mail in our inboxes, and social media can be a terrible bore on most days, but every once in awhile, we receive a wonderful email with good news or see something incredibly moving on our newsfeed.

He adds that it is the tendency of all living beings – not just humans but even pigeons, for example – to seek rewards for their actions. When the payout is unpredictable, it’s a lot more addictive and interesting to keep going. “I think there’s a sense in which we’re little pigeons sitting inside our boxes pecking away,” Wu says.

Now you know why you keep checking your Facebook. You’re just scouting for your reward – like the rest of us!