British people's guess for number of immigrants in UK prisons is staggeringly wrong

The British public has hugely inaccurate knowledge about crime rates, terrorism, immigration and health and often perceive things as much worse than they actually are, according to a survey.

According to an Ipsos Mori online poll of 38 countries, a majority of people around the world overestimate the statistics behind key issues from murder rates to the prevalence of diabetes. Some miss the mark by a "staggering" amount, say the survey authors.

The results show that the UK is no different in its off-kilter perceptions. Among some of the key findings in the Perils of Perception 2017 survey, British people believe that foreign-born prisoners make up a much higher proportion of the prison population than they actually do. According to the survey results, British people said 34% of all prisoners in UK jails were born in a foreign country. The actual figure is 11.8%.

That figure is in line with the overall population figures: around one in seven (14%) of people living in the UK were born abroad and one in 11 (9%) had non-British nationality in 2016.

Other perceived statistics were equally off the mark.

Two thirds of those surveyed think the murder rate is higher now than it was in 2000, when it in reality it is 29% lower. Only 19% of those surveyed correctly believe the murder rate has fallen.

Only 15% of those asked correctly said that deaths from terrorist attacks in Britain were lower between 2002-2016 – which saw 62 people killed in attacks - than they were between 1985-2000, when there were more than 300 deaths due to terrorism.

This perception could have been even more inaccurate if the results took into account the deaths from the four terror attacks in London and Manchester this year in which 36 innocent people were killed.

Another subject which the UK hugely overestimates is the number of teenage pregnancies. The public think that the proportion of pregnant girls and women aged 15-19 is as high as 19% (one in five) when it is actually a mere 1.4% (one in70).

More than half (55%) of Britons also still either believe or are unsure that there is a link between some vaccines and autism in healthy children despite the claims being dismissed and discredited by professionals for a number of years.

At least one in five (20%) still believe the link between vaccines and autism to be true, with 35% saying they don't know. A little under half (45%) of the UK say there is no link.

Despite the number of false beliefs, the UK ranks 9th out of the 39 countries in Ipsos Mori's "Misconception index".

South Africans are ranked first in terms of inaccurate perceptions about their country - for example 85% believing the murder rate is higher when it's actually down 29% - followed by Brazil and the Philippines.

Sweden, Norway and Denmark are the most accurate populations in terms of views of their country.

Bobby Duffy, managing director of Ipsos Mori Social Research Institute, said: "There are multiple reasons for these errors – from our struggle with maths and proportions, to media and political coverage of issues, to social psychology explanations of our mental shortcuts or biases.

"But in particular, we know from previous studies that this is partly because we overestimate what we worry about: the more we see coverage of an issue, the more prevalent we think it is, especially if that coverage is frightening or threatening.

"Our brains process negative information differently - it sticks with us and affects how we see realities. We're more worried than we should be about how our countries are and how they're changing.

"Some of the patterns are also worrying for our own decisions: our uncertainty about the link between vaccines and autism in healthy children, despite this being widely discredited, can affect our behaviour and therefore health outcomes in nations."