Heaven is where the police are English, the cooks are French, the mechanics are German, the lovers are Italian and everything is organized by the Swiss. Hell is where the police are German, the cooks are English, the mechanics are French, the lovers are Swiss, and everything is organized by the Italians. "

Obviously the national stereotypes in this old joke are generalizations(普遍化), but such stereotypes are often said to "exist for a reason". Is there actually a sliver of truth in them? Not likely, an international research team now says.

"National and cultural stereotypes do play an important role in how people see themselves and others, and being aware that these are not dependable is a useful thing," said study author Robert McCrae of the National Institute on Aging. "These are in fact unfounded stereotypes. They don't come from looking around you," McCrae said.

If national stereotypes aren't rooted in real experiences, then where do they come from? One possibility is that they reflect national values, which may become known from historical events. For example, many historians have argued that the spirit of American individualism has its origins in the experiences of the pioneers on the Old West.

Social scientists such as psychologist Richard Robins have given several other possible explanations for stereotypes and why they may be incorrect. Robins notes that some stereotypes may have been correct at one point in history and then remained unchanged while the culture changed.

We may be "hard-wired", to some degree, to keep incorrect stereotypes, since we are less likely to notice and remember information that is different from our stereotypes. Generally, according to Robins, when we meet people who are different from our stereotypes, we see them as unique individuals rather than typical national or cultural groups.