THINK twice the next time you tease your friend for their terrible dancing because it might be that they literally cannot hear the rhythm.

Scientists believe that beat deafness is an actual affliction and now they are seeking to prove it.

Jessica Phillips-Silver and a team at the International Laboratory for Brain, Music and Sound Research in Montreal, Canada, managed to find a subject willing to admit to his terrible dancing and submitted him to a series of (what must have been hilarious) tests.

They found that the only type of music 26-year-old Mathieu Dion could dance to was Techno due to the simple repetitive beat, which "was important because it told us he doesn't have a motor disorder," Phillips-Silver told NPR.

The researchers say that keeping time is actually quite a complex process involving different parts of the brain, so it will be some time before they can understand it properly.

Mathieu, for his part, seems surprisingly upbeat about the situation: "I am the first diagnosed in the world of having no rhythm, which is something great," he said.