Have you ever argued with a partner about the following things: the volume of the radio, time spent going out versus staying in, or one of you needing to be alone after work while the other wants to chat? If so, it's a good bet that one of you is introverted while the other's an extrovert, which puts you in some high-profile company: Eleanor and Franklin Roosevelt are one example of a successful introvert-extrovert partnership; Michelle and Barack Obama are another. "Opposites attract" is a cliché for a reason, and having different strengths can make you a great team, but knowing a bit more about how you react to things and why can help reduce some of the friction that comes from having completely different temperaments.
This is where Susan Cain comes in. Her debut book, published in the US in January and the UK this week, is called Quiet: The Power of Introverts in a World that Can't Stop Talking, and it contends that up to half of us are introverted. These introverts aren't all wallflowers though: most of them, she says, masquerade as extroverts to get by at school, at work, with family and in social situations because we live in a world that rewards attention-seekers and smooth talkers. This takes its toll: even the best-adapted introverts need to take time to "recharge" in peace.
Cain herself is an introvert - as a child, she says in a TED talk that's been watched on the internet almost two million times, she would head off to summer camp with a suitcase full of books - but she became a Wall Street lawyer before realising the career didn't suit her and switched to writing. She's also married to an extrovert, and describes the relationship as having "a real sense of yin and yang". She jokes that "together we're one fully functioning human being" and says that she loves that her husband never runs out of something to say. "He's a lot of fun to be with, and when we go out to a party he does the job for both of us of being the large presence in the room." In turn, he appreciates her "deeper and more reflective attitude to life".
There can be problems though. Kat, a teacher in her late 20s, and her fiancé Jim, a web developer whom she describes as a "really thoughtful person" are a blissfully engaged couple - although their opposite temperaments can sometimes rub each other up the wrong way. Kat loves meeting new people and would happily be out socialising most nights of the week, but she hates that she has to choose between parties and spending time with her more introverted boyfriend, who prefers to stay in reading, working on websites or watching films. Sometimes she persuades Jim to go out, but if he doesn't have a good time it can cause resentment.
Susan Cain says that this is the most common source of conflict within the introvert-extrovert couples that she interviewed for her book, and she recommends laying down ground rules rather than haggling with each other every weekend. Decide to go out one night per weekend, for instance, or compromise on places that aren't too noisy and crowded. In her book, Cain suggests changing the format of dinner parties to an informal buffet where the quieter partner can have a one-on-one conversation in a cosy nook. Negotiating in advance also helps with that radio volume problem: studies that Cain cites in her book show that introverts find it harder to think against a background of loud noise, whereas that kind of stimulation can actually help extroverts.