Pupils who take the Monty Python approach and always look on the bright side do better in school and adult life than their IQ and aptitude tests show they should.
Carol Craig, director of the Glasgow-based Centre for Confidence and Well-being, told primary heads at their annual conference in Edinburgh that they should encourage pupils to be optimists, overcoming the Scottish culture of pessimism.
"There is overwhelming evidence to show that you can shift pessimism if you re-educate pupils to think in a different way," Dr Craig said. "You can increase their optimism by 20-30 per cent if you show them their pessimistic thinking is often driven by fear and flawed thinking, not based on fact."
Dr Craig, who works with schools on assertiveness training and confidence-building and is author of The Scots' Crisis of Confidence said that it was not just pupils who suffered. "Teachers as a group are terrified of criticism. It is a major issue for teachers to be criticised and getting it wrong."
Under questioning, she accepted that the media played a major part in creating such a negative climate around the profession.
Dr Craig urged teachers to find new definitions of self-confidence in the classroom. Too often people saw it as the ability to stand up in front of the class and talk. "You need to broaden your notion of what confidence is.
It's not just something about communicating in a certain way. Look for how it comes out in a variety of ways and try to support that with individuals, so that they feel good about who they are."
Dr Craig called for small changes with individual pupils that would have a cumulative effect. "If people can just be 20 per cent more optimistic and believe problems are soluble, if they can be 10 or 20 per cent more positive than they were before, and if they could just even smile a bit more sometimes at a certain individual, then that can make enough of a difference," she said.
Primaries were much better than secondaries in building confidence, she suggested.
Dr Craig said that individual self-confidence mattered more than ever as people regularly changed jobs, acquired new skills and moved around. "The people who can cope with change are the people who are most confident. And the people who thrive best are the most optimistic," she said.