10 of The Most Counter-Intuitive Psychology Findings Ever Published

But anyway, such a criticism of the field misses the point. Many findings in psychology can seem obvious after the fact, but we can't know in advance which aspects of folk wisdom will stand up to scientific scrutiny. Striving for the objective truth through empirical testing – that's what science is for, whether applied to molecules or minds.

That said, it's always fun to share those findings that clash with received wisdom. So for your reading pleasure (and for the next time someone asks you the "common sense" question), here are 10 particularly counter-intuitive findings from the psychology archives. Please use comments to share your own favourites that we've missed.

1. Self-help Mantras Can Do More Harm Than Good

If you've got low self-esteem, you might want to avoid uttering positive mantras such as "I'm a lovable person". A 2009 study found that people lacking in self-belief who spoke this phrase to themselves didn't feel any better afterwards. In fact they felt worse, possibly because the repeated utterance led them to generate contradictory thoughts automatically. On a related note, there's evidence that positive fantasies can also backfire. It's thought that visualising your aims can cultivate a relaxed mindset that leads you to overlook the hurdles between you and your goals.

2. People Do Not Learn Better When Taught Via Their Preferred "Learning Style"

An incredibly popular idea, including among teachers, is that pupils learn better when they are taught information via their preferred modality, such as auditory, visual or by doing. In fact research has shown that people do not perform better when they are taught information via the modality that they say they prefer. A 2008 review of the learning styles concept put it like this: "there is no adequate evidence base to justify incorporating learning-styles assessments into general educational practice." Want more? – here's all you need to know about the learning styles myth in 2 minutes.

3. Criminals Show Cooperation and Prosocial Behaviour in Economic Games

It's easy to demonise people who have broken the law. However, recent studies using economic games that test fairness and cooperation show that this is short-sighted. Last year, researchers observed prisoners' performance on a famous game known as the "prisoner's dilemma" – the convicted criminals actually displayed more cooperation during the game than undergrad students. Similarly, another study published this year found that people with a criminal record displayed just as much "prosocial motivation" (i.e. they distributed money fairly) in the "dictator game" as those without such a record.

4. Bottling Up Your Anger May Actually Be Good For You

Folk wisdom states that it's better to relieve your anger by letting it out. In fact a tendency to lose one's temper tends to go hand in hand with poorer health. Another study found that hitting a punch-bag while thinking about the person who made you angry actually just makes you angrier. It's a complicated area, and expressing anger constructively may sometimes be a good thing to do, but the old rule that's it always better to let it all it out is definitely flawed.

5. We Make Many Decisions Mindlessly

Unless we're exhausted or intoxicated, we usually feel as though we are very much in control of our own choices and that we make them consciously and deliberately. This intuitive view is challenged by research on what's known as "choice blindness". In one study from 2005, participants picked out the face they found more attractive from successive pairs of photos. When researchers used sleight of hand to switch the chosen photo for the rejected photo, participants proceeded to justify their choice all the same, apparently ignorant of the switch. It was a similar story in 2010 when participants chose between different jams.

6. Opposites Don't Attract

When it comes to human relationships, the aphorism that "opposites attract" turns out to be wide of the mark. There are of course exceptions, but mountains of evidence highlights how we are drawn to friends and romantic partners who are similar to ourselves, whether in terms of physical appearance, their personality, interests, or beliefs – known as "homophily". To take just two examples, a study from 2010 found that people found faces more attractive when (unbeknown to them) they'd been morphed with their own; and a paper from 2011 found that people tend to choose to sit near others who look like themselves.

7. Wine Experts Don't Know if They're Smelling Red or White Wine

There is a vast literature on the limitations of expertise (for instance, political pundits are mostly useless at predicting electoral outcomes), but one of my favourite examples concerns people who study wine. A 2001 investigation showed that all it took to trick trainee oenologists into thinking a white wine smelt of red wine, was to dye it red. This research also challenges the intuitive belief that our senses are largely separate – in fact, perceptual experience derives from a blending of the senses, as shown for example via the McGurk Effect.

8. It Helps to Have Narcissists on Your Team

We usually think of narcissists – people with inflated views of their own skills and self-importance – as individuals to avoid. However, a study published in 2010 found that their presence can have a beneficial effect in the context of creative team work. When groups of four people were challenged to come up with new ways for a company to improve, it was the groups with two narcissists in their ranks who performed the best. The researchers think the presence of some narcissists helps generate healthy in-group competition.

9. Placebo Treatments Can Work Even When People Are Told It's A Placebo

The amazing power of the placebo effect – the way that our beliefs about the action of an inert medicine can trigger substantial physiological effects – is itself, counter-intuitive. More surprising perhaps, is that the effect can still occur even when people know the medicine is inert. This was shown in a 2010 study involving people with IBS. "Our study suggests that openly described inert interventions when delivered with a plausible rationale can produce placebo responses," the researchers said.

10. Sometimes a Pregnant Woman's Depression is Advantageous For Her Baby

There is lots of evidence showing the adverse effects of a stressful pregnancy. But dig deeper into this field and you find some surprising results. For instance, a 2012 study uncovered an association between depression in pregnancy and superior functioning in the child at ages three and six months. This was found in the specific context in which the mother's depression continued into the postnatal period. The finding is consistent with the "predictive-adaptive response model", which says that adversity in-utero can have adaptive advantages if adversity is also encountered after birth.