More than 200 female students at the University of British Columbia in Vancouver, Canada, were once told that boys typically score 5 percentage points higher in mathematics than girls. It wasn’t actually true. It was part of a study that examined how our beliefs influence our lives.

Half of the girls were told that the difference in math scores was down to a gene on the Y chromosome (that only boys have) that increased energy supply to a part of the brain involved in performing mental tasks. These girls believed themselves to be at a genetic disadvantage.

The other half of the girls were told that the difference in math scores was simply down to stereotyping and that girls are just as good at mathematics as boys are. They were told that parents and teachers, themselves believing that boys are more mathematical, bias their expectations from an early age and treat boys and girls differently.

When they all sat a math test some time later, the girls who believed the difference was just due to stereotyping significantly outperformed the girls who believed they were at a genetic disadvantage. Each girl’s performance came down to what she believed.

In other research, this time at the University of Wisconsin, a study of 30,000 people found that the belief that stress was bad for you was arguably worse than stress itself.

In fact, the belief that stress is bad for you ranked 15th in the leading causes of death in the United states, just two places behind hypertension and hypertensive renal disease (13th) and one place behind Parkinson’s disease (14th).

Tracking health over decades, it turned out that being highly stressed and believing it’s bad for you increased the risk of early death by 43% when compared with having the same amount of stress but believing it’s good for you.

There was also a higher death rate in some people who experienced small amounts of stress but who believed that stress was bad for them than there was in some highly stressed people who believed that stress was good for them.

This is a tricky one because, without wishing to bias your expectations, we would do well to keep a check on our stress levels. The study also showed that chronic stress is itself linked with a number of poor health outcomes. However, if we believe the above research, perhaps our beliefs about stress can moderate the effects a little.

It’s a placebo effect, of sorts. Take painkillers, for example. According to some research, a placebo packaged in the box of a well-known and respected brand can work just as well as an actual painkiller that’s in plain packaging that simply says, ‘Analgesic’. Our beliefs can make placebos work better and make painkillers less effective. The painkiller works, of course, but our beliefs about it matter too.

Beyond maths scores and stress, life is very much influenced by our beliefs. A person who believes himself to be a failure views obstacles as insurmountable problems, whereas someone who believes herself to be successful tackles problems head on with the attitude that any problem can be solved. If the two were to meet the same problem at the same time, who succeeds or not often has little to do with talent or intelligence, but about what each person believes about themselves.

I think many would agree with this when considering their own lives. How many times have you viewed someone getting ahead who has less talent or ability than you, but who believes in themselves more?

It’s both a fortunate and unfortunate fact. Fortunate for those who possess self-confidence and belief, but unfortunate (and stressful) for those who have talent and have worked hard for years to hone their craft and abilities, only to see opportunities go to some who simply do more talking.

Of course, it’s absolutely not true that everyone who gets ahead is simply good at talking themselves up. A great many people who rise to the highest levels in business, science, and the arts do so because they are very good at what they do. In fact, in some areas it would be impossible to do so without true ability. But there are times when self-belief plays more of a role than ability, and most people when asked have a tale or two to share.

And let’s not make self-belief out to be a villain. We all need self-belief. It often wins us opportunities, which we then build upon, often to become, retrospectively, what we believed about ourselves in the first place.

This is something I have observed in my own life. Rarely have I gained all the knowledge I believed I needed before I did something. Life frequently asks us to be brave. Most of the time, we learn as we go along. Stepping up and out in life places us in situations where we then learn what we wanted to have learned in the first place. It’s a bit of a paradox.

I learned to write in the process of writing my first book, not before I embarked on writing it. If I had studied all I believed I needed to know, I might never have started writing it in the first place. There’s a balance to be had in life.

A good dose of self-belief can be a very good thing, helping us get to where we want to go. Too much might get us into some bother, or cause others some bother who are relying on our expertise, which we simply don’t possess enough of. Yet, too little might keep us out of doing what we want to do. Somewhere in the middle lies a sweet spot.

But generally speaking, in life, if you believe you can do something, you’ll usually fare better than if you believe you can’t. You’re more likely to try in the first place, more likely to spot solutions, and more likely to go that extra mile if it’s needed.

On that note, I’d like to leave you with the words of Christopher Robin, from A. A. Milne’s, Winnie-the-Pooh, “You are braver than you believe, stronger than you seem, and smarter than you think.”

**By David R. Hamilton PhD