Over the past few years, she’s helped some of the world’s biggest corporations - IBM, General Motors and Goldman Sachs. She recently published her ideas in the business bible Same Words, Different Language and, unsurprisingly, many of Annis’s theories can be applied to personal relationships.

Consider the negotiating hypothesis: Annis suggests that in debate and discussion, men cannot read female facial expression, they follow a fixed conversation goal and argue to sort things out; women, on the other hand, can read facial expressions well, don’t start a discussion with a fixed solution in mind, and never see arguing as positive.

Sarah, aged 35, believes this could help explain why and how she argues with her boyfriend Phil, aged 31. For example, they recently went out for a meal to discuss moving in together; before arriving, he’d decided she should move into his house (it was bigger and closer to work), while Sarah had no fixed idea of what the solution should be. She began the conversation hoping to explore various possibilities, while he presented the case for living at his place as if in court. When she began suggesting other solutions, the conversation immediately turned into an argument, as he defended his idea, assuming that she was attacking it. Sarah felt upset because they were quarrelling, and eventually this showed on her face. When things became more heated, she stormed out of the restaurant, wondering why he’d been so unreasonable, and frustrated that he hadn’t noticed her distress. Her flight baffled Phil, who assumed the argument was a valid extension of the discussion, and hadn’t realised she was put out. "Had we known about our different thought processes, it might have helped," Sarah concedes, grudgingly.

Annis’s theories on criticism can be equally effortlessly transferred from a corporate environment into a personal scenario. Men, she says, view criticism as constructive advice; they’ll be grateful for it and act on it. Women, however, see it as attack, viewing every interaction as personal and condescending because they’ve usually worked out what they’re doing wrong themselves. Annis explains in her book that because women take everything personally, men need to word their criticisms "I like you, but..." and, because they’ve almost certainly already registered the fault, ask how they think they could improve, rather than telling them.

In her stress theory, Annis suggests that men react to anger, stress and frustration by shouting or hitting, while women cry. Both sexes assume the other’s form of release relates directly to them. This happened continually throughout a previous relationship of mine — my ex would lose his rag and hit the nearest hard object. One day, we were preparing a meal for a cosy night on the sofa. We’d been chatting happily in the kitchen for a good hour, when all of a sudden the mood changed, simply because when he shut the fridge door several of the magnets on it fell off. He reacted by swearing ferociously, turning red, stamping on the magnets and slamming the fridge door over and over. When I look back on it now, it’s entirely obvious that his reaction had nothing to do with me, but at the time I assumed it did. I used to respond to these regular outbursts by getting upset, which made him angrier still, and we’d have a full-blown screaming match. I now wonder if our misunderstanding led to the end of the relationship, though I have no desire to start it up again.

Although there is obvious merit in a lot of Annis’s theories, they are flawed in one fairly significant way. Just as I could spot the male character traits in male acquaintances, I could find them in female ones, too.

Is Annis’s theory imperfect? Relationship coach Phil Flanagan thinks so. "I believe the differences she describes aren’t male and female, but masculine and feminine. The different forms of expression are spot on, but they’re not determined by sex. Being able to read mood and opinion from facial expression is feminine, as is musical ability, creativity, sensitivity and many other things, and although more women have these traits, many men have them, too. Women, it follows, can be masculine — a masculine woman will shout when she’s angry, take criticism well and so on."

The masculine-feminine system is one that Flanagan uses in seminars he runs on relating to others at work and in relationships, and he says that it never goes down well. "People prefer the Annis approach because they feel uncomfortable being associated with the opposite sex. Men don’t want to be labelled feminine and vice versa. But once they realise it doesn’t make you less of a man or woman, it works."

Thus the Annis theory, once applied to masculine and feminine people, rather than men and women, is most effective. Being able to spot the telltale signs of masculinity and femininity helps us work out how people, in particular partners, communicate. Then their behaviour, once baffling, won’t be quite as infuriating.

— The Guardian