People in many countries generally think their homeland did the most in the Second World War.

Which country put the most effort into the Second World War? It depends on whom you ask.

Henry Roediger III at Washington University in St. Louis, Missouri, and his colleagues surveyed 1,338 people from 11 countries that participated in the Second World War about their homeland’s contribution. The team found that individuals from many nations tended to overestimate their countries’ efforts, although the researchers also note that precise measurements of a nation’s contribution to the war are impossible.

People from Russia, the United Kingdom and the United States assigned more than 50% of the victory to their own country. Participants from Germany — one of the defeated powers — assigned their country 64% of the effort in the losing cause.

Although far more Soviet soldiers died than did soldiers from any other country, participants from outside Russia tended to minimize Soviet efforts. Few respondents listed the Battle of Stalingrad as one of the war’s most important events, although most historians consider it a turning point.

These skewed perceptions reveal an example of what the researchers call ‘national narcissism’ — a tendency to believe that one’s own country is exceptional compared with other countries.