Slowly but surely it’s getting harder: For decades, senior business people and politicians have been saying that German committees, podiums and leadership circles should be more pluralistic and that there should be equal representation of both sexes. But it’s not really happening. For those who want to know why no real progress is being made, the answers are now available. Swiss behavioural economist Iris Bohnet, who lectures at Harvard, has worked her way through countless empirical studies. And the result may be of bitter offence to our egos: Most of the decisions we make are not actually the result of free and rational will.

As we negotiate life and make decisions, human beings are far more affected by external circumstances and accepted norms than they realise. For example, stereotypes about men and women. Even if we think we are behaving in an impartial way, more often than not, we are not. The majority of time we see men and women behave the way we believe they will. And if a person does not behave as we expect – say, a woman who comes across as demanding and decisive – then we find that unpleasant.

That is why good will and clumsy mechanisms like rigid quotas won’t suffice if we really want to change our perceptions, and make things more equal. Instead we need to analyse our practices and customs and change them, according to the contexts. Bohnet describes this as behavioural design.

For example, in 1970, the number of women playing in the US’ top orchestras bobbed up and down at around 5 percent, despite the fact that jury members were absolutely certain they were choosing candidates objectively, based upon musicianship and skill. Could it be that women are just worse musicians? Unlikely. So orchestras began to hold auditions by having the candidates play behind a screen. Wonder of wonders! The opportunities for female musicians rose by as much as 50 percent. And in the meantime, the ensembles are now over 35 percent female. Bohnet recommends that companies design their procedures in a more neutral way. However it is not usually as obvious as with the orchestras.

The design of multi-choice questionnaires often influences how the different genders perform. If the subject loses a point when giving the wrong answer, women will tend not to give any answer - that is, they won’t make a choice - if they are not certain of it. Men, on the other hand, tend to guess - and often, chance has it that they are correct. Without the threat of losing a point, women are just as likely to guess. And as if by magic, their results also improve significantly.

This statistically quantifiable disadvantage for women is based less on bad intentions than on psychology. If we believe something already, we recognise it when we see it and we act accordingly, as if that was the reality. It’s a vicious circle – but Bohnet has suggestions to combat this.

Traditional measures to combat inequality are futile and may even be counter-productive. In the worst case scenario they send females toward unnecessary coaching or training that never even changes anything.

People don’t feel good when confronted with the opposite of a stereotype they have in mind. That is why men and women are treated so differently during salary negotiations. Men who ask for a lot of money are seen as the epitome of masculinity. Women who act the same way are working against ideas about traditional femininity and come across as disagreeable. So it doesn’t help for women just to act like men. They might start off with a good salary but end up being seen as a bossy cow by others in the workplace.

Women can however do something for themselves. It is an acceptable thing for a female to fight for others, so: I don’t mind so much about the money myself, but I wouldn’t want to be a part of making the gender pay gap bigger here. That gives the woman a good chance at a better salary but also allows her to maintain that sympathetic stereotype. On the other hand, in doing this, the female employee is also playing to stereotype and only strengthening that prejudice.

It is a great strength of this book that it points out that there is no single, correct answer. We need to experiment and we need to recognise that most of the daily negotiations we do, that we believe are neutral, are in fact not neutral at all.

And it is not only men who judge women, women judge each other critically too. This explains why women who end up in leadership positions don’t automatically bring other women to the top with them. Apparently female bosses also tend to be more critical of their male staff – this could be another reason that males speak badly about their female superiors. Statistically they get a harder time from a female boss than a male one.

It is also interesting to look more carefully at mechanisms that are supposed to promote equality but which have been counter-productive. Those half-hearted sessions in diversity training at work, for example. There is a widespread behaviour that sees human beings, who believe they have just done something good, feel justified in doing something bad afterwards. Male managers, who were forced to attend a one-day diversity workshop, then lean toward promoting male staff instead. Good intentions do not necessarily equal good deeds.

But there is some positive news in this book too. There are more opportunities to increase diversity and equal opportunities in your own organisation than most of us ever dreamed: You only have to want it.