For the latest batch of would-be Apprentices, confidence is seen as key to achieving success in Sir Alan Sugar's boardroom.

But according to new research, that same attribute might prove to be the downfall of the remaining candidates, and their counterparts in the real world.

The study, led by academics at Leicester University, found that entrepreneurs who have "an inflated sense of their own abilities" are more likely to lose their battle to make it big in the business world.

Dr Briony Pulford and Professor Andrew Colman, who conducted the study with Dr Fergus Bolger, formerly of Durham University, said that people who are "full of themselves" often try to launch new businesses in marketplaces that are already saturated.

Ms Pulford, of Leicester's school of psychology, said ""over-confidence"" was one reason why many start-up companies failed in their first few years and warned that people with "absolute confidence in their own abilities" were most at risk.

"Our findings have practical implications for people starting new businesses," she said. "They should beware of over-confidence', and they should be especially wary when entering small markets or markets that seem to present easy business opportunities, because over-entry seems most likely in these circumstances."

Researchers set up a game that simulated market conditions where participants stood to gain capital or make a loss, based on decisions they made in different market scenarios.

The players had to choose whether or not to open restaurants given different market scenarios, using a combination of skill and luck in order to perform.

Ms Pulford said the results of the study, which was funded by the Economic and Social Research Council and is published in the journal Experimental Psychology, showed that many "over- confident" candidates were also "over-optimistic".

Many of the 16 candidates on the current series of The Apprentice have made viewers cringe with their confidence as they battle it out to win a six-figure contract working for Sir Alan.

Nicholas de Lacy-Brown, 23, proudly told cameras: "I haven't failed at anything," shortly before becoming the first to be fired by the Amstrad tycoon.

Jennifer Maguire, 27, who was fired last week, claimed to be the "best salesperson in Europe", while Ian Stringer, 26, insisted that the word "loser" was not in his vocabulary.

However, Sir Alan has fired many of those who appear to be the most confident, including Kevin Shaw, who was told by Sir Alan that there was a "smell of arrogance" about him.

Karen Bremner, who took part in the 2006 series, said yesterday that "confidence" was viewed as vital for survival in the TV series. "There is a perception on The Apprentice that you have to be bolshy and aggressive," she said. "They are the traits that Sir Alan puts forward as positive attributes."

Ms Bremner, who opened her own boutique, karenb, in Broughty Ferry last year, added: "The Apprentice shows a very short-sighted business strategy. In all of the tasks the candidates are trying to get the best deal possible. In real business, if you had customers you were dealing with again and they felt like they had been cheated then they wouldn't be back."

Dr Cynthia McVey, head of psychology at Glasgow Caledonian University, warned entrepreneurs about being over-confident when making business decisions.

"There can be an element of luck involved," she said. "If you're taking a really big risk and you happen to have a bit of luck, then that sometimes feeds your confidence. It might make you a bit arrogant and lead you to take further risks because you have not recognised that you have been fortunate.

"If there is a mismatch between your level of confidence and level of ability, then the chances are you will rush into situations with confidence where you don't have the required ability to deal with them."