Being more intelligent does not stop people being racist – it simply makes them better at covering it up.

A study found that they were just as likely to be prejudiced as their less educated peers but did not act on their feelings.

Or, more accurately, did not naively express their beliefs, while still acting upon them. In contrast, the intelligent are more likely to send their children to, say, Sidwell Friends School than to a D.C. public school.

Researcher Geoffrey Wodtke examined the attitudes of more than 20,000 white respondents from a society-wide survey.

He then looked at how their cognitive ability, or how they processed information, was shown in their attitudes to black people.

They were also asked about  policies designed to counter racial bias.

Mr Wodtke, of the University of Michigan, said: ‘High-ability whites are less likely to report prejudiced attitudes and more likely to say they support racial integration in principle.

‘There’s a disconnect between the attitudes intelligent whites support in principle and their attitudes toward policies designed to realise racial  equality in practice.’

For example, four years after demanding that the term limit law preventing Michael Bloomberg from a third term as mayor be ignored, New York City liberals are shocked, shocked to discover today that racial profiling has been going on under Bloomberg.

But who could have known? If anybody had told us that millions of blacks and Latins were being stopped and frisked in New York, we would have done something about it. It's not like we wanted to make the point to blacks and Latins about who is in charge in New York and if they don't like it, well, there are Greyhound buses leaving from the Port Authority terminal every few minutes. No, it's just that, uh, there weren't enough studies being done on stop and frisk over the last decade for us to notice!

He said that in housing, nearly all whites with advanced cognitive abilities agreed that ‘whites have no right to segregate their neighbourhoods’.

But, added Mr Wodtke, nearly half were content to allow prejudicial practices to continue rather than support laws to open up housing to ethnic minorities.

He said the study showed racism and prejudice were not simply a result of low mental ability.

Instead, they result from the need of dominant groups to ‘legitimise and protect’ their privileged social position over other social groupings.

More intelligent citizens ‘are just better’ at this, added Mr Wodtke at the annual meeting of the American Sociological Association.

In modern America, ‘this means that intelligent whites say all the right things about racial equality in principle but they just don’t actually do anything that would eliminate their privileges’.

Mr Wodtke warned: ‘Any effort to point out or eliminate these privileges strikes them as a grave injustice.'