Most Europeans think their societies are far less equal than they are, while Americans are unusual in believing that their country is somewhat more equal than it really is.

A German report sheds new light on the political challenges involved in tax, income distribution and social fairness and raises fresh questions in the equality debate recently revived by French economist Thomas Piketty.

“The results of the study suggest that, in the political debate on income distribution, it is often not the facts that count but [perceptions],” says Professor Michael Hüther, director of the Cologne-based IW economic institute, which carried out the research.

Judith Niehues is due to present her findings this week at Germany’s Lindau economic conference, attended by Nobel laureates. She compared actual and perceived income levels in the US and 23 EU countries, using economic data and an international social attitudes study based on polling about 1,000 people in each country.

She found that people in Europe underestimate the proportion of middle-income earners and overestimate the proportion of the poor, commonly defined as people on incomes of 60 per cent or less of the median.

Only the US has a more unequal income distribution than its citizens imagined, with many more poor people.

Explore the report’s findings on different countries

In Europe, people on middle incomes are far more numerous than those at the bottom or the top of the pay ladder. So a European income distribution chart resembles a barrel, with a bulge in the middle. But many people see it as a tower standing on a broad plinth, with a small elite, a modest middle-class and a big base of low earners.

This is particularly true in Germany and France, where people see income distribution as far more unequal than it really is. By contrast in Britain and Spain, where income distribution is somewhat less equal than in France and Germany, people’s perceptions are more accurate.

In the US, more than 30 per cent of Americans have incomes of 60 per cent or less of the median. But most people think that only 24 per cent of their fellow citizens are at this level. “The middle class is truly smaller in the USA and the lower income group considerably more numerous than its citizens suppose,” says a summary of the study.

The report suggests this might be partly linked to social mobility in the US – people may be less focused on inequality if they think they are climbing the income ladder. The relative lack of concern about inequality could explain why pressure for redistributive taxation is lower in the US than on the other side of the Atlantic.

In Europe, the gap between perception and reality is particularly wide in the former Communist states, with citizens convinced their countries are far less equal than they are.

In addition to perceptions of income distribution, the report also looks at levels of concern about inequality. This tends to be greater in countries with higher levels of perceived inequality – such as France and Germany – than in countries with higher levels of actual inequality – such as the UK and Spain. More than 50 per cent of Germans and 79 per cent of French think income differentials are too great, compared with around 30 per cent of Britons and Spaniards.

The report suggests that all this should matter to policymakers designing tax and social transfer systems because actual levels of inequality seem less important to voters than perceived levels of inequality.

But it does not address the core argument in Mr Piketty’s book, which focused on inequalities of wealth rather than income, and argued that wealth inequalities are more significant in driving overall social inequality.

Subjective Perceptions of Inequality and Redistributive Preferences: An International Comparison, by Judith Niehues, Cologne Institute for Economic Research