It’s a debate that will be familiar with many millenial friendship groups – and has no doubt dominated plenty of recent conversations.

Just what is it about Taylor Swift that makes her so stratospherically popular?

Not only has her music garnered more than 26 billion streams on Spotify and helped to attract more than 281 million to her Instagram page, she’s also engaged a brand new audience as the girlfriend of Kansas City Chiefs tight end Travis Kelce.

Meanwhile, millions more tuned in to last night’s Superbowl game to watch her in the VIP box, cheering on her boyfriend.

Now, experts have revealed the intriguing, science-based reasons why Swift is such a global phenomenon – and it’s got little to do with her true personality.

One of the major factors, experts say, is simple familiarity. The more Taylor and her music surround our daily lives, the more we grow to like her.

This is a psychological phenomemon known as the ‘mere exposure effect’ – studies involving repeated television commercials have found viewers grow to prefer the products they see on screen most often.

A study published in PLOS One had participants undergo imaging tests to see which types of music activated the brain’s reward system.

The researchers found that people who listened to music they were familiar with were more likely to have the pleasure centers in their brains light up than those who listened to music that they said they liked.

‘Familiarity seems to be a crucial factor in making the listeners emotionally engaged with music,’ the team wrote.

Another reason for the 34 year-old’s popularity is that her songs are uniquely catchy. And scientists have dissected what makes an earworm.

A 2017 study from the American Psychological Association, for example, found that catchy songs include ‘melodic turning points’ between different sections of the song like the verse, chorus, and bridge.

Researchers note that, in Taylor’s case, she often uses one-note melodies in certain sections of her songs that slowly build up.