It's bad news for the clueless, with landmark research finding that incompetent people believe they perform well at the very tasks they're most likely to fail.

Researchers Justin Kruger and David Dunning found that people who are not particularly good at things - like grammar, social interaction and even joke telling - end up with a two-pronged problem:

• Firstly their lack of ability can be an issue in itself.
  
  
• Secondly, it is compounded by the fact that they tend to significantly overestimate their abilities, rather than recognise their ineptitude.
  

What these people lack, according to Kruger and Dunning, is metacognition  -  a term which psychologists use to describe self-evaluation skills.

How was the study conducted?

The authors asked participants to complete a range of tests and then state how well they thought they did in each one of them, as well as how competent they felt they were in the subject matter overall.

• The tests involved logical reasoning and grammar, as well as social abilities like seeing the humour in a joke.
  
  
• They were sometimes shown test papers of some of the other participants sitting the same test and were given the opportunity to re-estimate their own performance.
  
  
• In one study, some participants were given a brief course of training to improve their skills and were then asked to re-evaluate their performance.

What did the authors find?

The lower the participants scored in the tests, the more they over-estimated their test performance and ability. These people found it hard to distinguish accuracy from error.

The grammatically-challenged participants who thought they'd blitzed the grammar test, for example, failed to perceive the problems with their own performance, even after they were shown the test papers of some of the better candidates.

On the positive side, when the participants with low levels of ability in logic and reasoning took a short course aimed at improving their competence, they improved their accuracy at self-assessment. While these participants still overestimated their abilities, they were more realistic than prior to their training.

Conversely, those in the top bracket for ability tended to accurately perceive how they performed in a test, but underestimate their comparative ability in relation to others.

"These participants assumed that because they performed so well, their peers must have performed well likewise" the authors explained.

What did the authors conclude?

"One puzzling aspect of our results is how the incompetent fail, through life experience, to learn that they are unskilled" the authors mused. Unfortunately, they concluded, people often don't receive criticism about their skills in day to day life. Society has made us uncomfortable about giving this sort of negative feedback.

Kruger J. and Dunning D. Unskilled and Unaware of It: How Difficulties in Recognizing One's Own Incompetence Lead to Inflated Self Assessments. 1999. Journal of Personality and Social Psychology; 1121-1134