We make all sorts of assumptions based on someone's accent.
Whether you have a slow Texas drawl, honeyed French tones or a Liverpudlian twang, people tend to believe certain things about you just seconds after you open your mouth.
This is particularly true in the UK - a place with the most dialects per head of any nation in the world - where ideas about class make it about as easy to shake off how "posh" or "common" you appear as shaking off your own tongue.
But we are not alone in believing someone's accent reveals some inner truth about them.
Forty-seven per cent of Americans think that the British accent - usually understood as the Queen's English, or a southern-centric dialect - is very "sophisticated". As we all saw in Love Actually, this worked out pretty nicely for Colin when he jetted off to Wisconsin to impress women.
Those in southern states are thought, fairly patronisingly, to be "nice but perhaps a little uneducated". Hmmm, thanks.
Meanwhile those on the East Coast, home to the US of A's greatest universities and first settler towns, are thought to sound "intelligent".
But New Yorkers were bluntly assessed by 51 per cent of Americans as "rude". (Donald Trump is from New York. Just saying.)
But these are domestic dialects, or as a video from our favourite science bloggers ASAP Science explains, which explains all these differences terms it, "non-native accents".
What about the accent of someone who has learnt to speak a second language?
Usefully for everyone whose French and Spanish lessons began when they were about 12, there's no hope of sounding like a Parisian or Barcelonian if you start to acquire a language at exactly that age.
The video explains:
Even if you move to another country, the length of residence has almost no effect on your accent after 12 years old.
Even more interestingly, your hopes of pronouncing and even hearing certain sounds - known as phenomes - is limited to the very first six months of your life.
Babies from Japan and the US listened to some sounds over and over at six months old - "la, la, la" and "la, la, ra" - English sounds that do not exist in Japanese - in a groundbreaking 2010 study into language from the University of Washington.
Babies of both nationalities responded to the difference in sound.
But when they were 10 to 12 months old, the Japanese babies could not tell the difference between the sounds any more - showing how quickly you learn one set of sounds and stay stuck with them forever.
The exception is bilingual kids, who have an immediate advantage.
Being versed fluently in two or more languages from birth gives you denser and stronger grey and white matter in the brain, and gives you better focus and problem solving skills.
So the rule is: you might do a great Scots impression, but you're never going to be able to speak, or even hear, all the tiny subtleties in that thick Glaswegian if you didn't start listening to it as a bonny wee babby.