The study measured the gap between public perception and reality on Islamic immigration old and new, finding French respondents were the most likely to overstate their country's current and projected Muslim population. On average, the French estimate 31% of the population is Muslim (the reality, according to Pew Research, is actually 7.5%), and this total will rise to 40% by 2020 (Pew's forecast is 8.3%).
Belgians, Germans and Italians all guessed over a fifth of their populations were Muslim, but in reality the respective totals are 7, 5 and 3.7 percent. Respondents in all three countries also greatly overestimated how much their Muslim population would've grown by 2020, although Italians were the worst offenders in this regard, projecting this figure to rise to a third of the overall population, while the actual projection is 4.9 percent.
UK residents placed the country's Muslim population at 15 percent, three times the actual figure, while they projected the 2020 population to be 22 percent almost six times the actual figure.
However, the UK scored very highly in Ipsos' 'index of ignorance' rankings, finishing second in terms of most accurate responses, behind the Netherlands.
Dutch respondents had significant misperceptions of their own in certain areas. The survey also examined how effectively people could measure national attitudes to abortion, homosexuality and pre-marital sex, asking respondents what proportion of their overall population considered them morally unacceptable. The Dutch were the most inaccurate on every single question.
Respondents expected personal objections to abortion to run at 37 percent, when the reality is 8 percent, and believed objections to homosexuality and sex before marriage to be around 36 percent and 34 percent respectively, when the reality is 5 percent on each question.
Bobby Duffy, managing director of the Ipsos MORI Social Research Institute in London, said the results show populations get a lot wrong.
"Across all 40 countries in the study, each population gets a lot wrong. There are multiple reasons for these errors — from our struggle with simple maths and proportions, to media coverage of issues, to social psychology explanations of our mental shortcuts or biases. It is also clear from our index that the countries who tend to do worst have relatively low internet penetrations."
In all, Ipsos MORI conducted 27,250 interviews in the 40 countries.