The assumption of national psychology is that different ethnic groups, or the people living in a national territory, are characterized by a distinctive "mix" of human attitudes, values, emotions, motivation and abilities which is culturally reinforced by language, the family, schooling, the state and the media.
According to the German pioneer psychologist Wilhelm Wundt, the attempt to theorize scientifically about national psychology dates from the mid-19th century [2].
In post-1871 Germany, but especially during the Third Reich, some German professors of linguistics and literature tried to influence English studies with a politically motivated "cultural science", which Ernst Leisi called the "Nationalpsychologische Methode.
[2] Around 1900, national psychology had become an accepted topic of study in the social sciences, at universities in Europe and North America.
Marketing and Media experts have found that at most people can identify a representative stereotype, archetype or caricature which symbolises a particular ethnic group, or characteristic ways of relating which a nation has.
Some additional complications are, that: Because of all these difficulties in defining national psychology, often the most insightful portrayals of it are not really "scientific", but are found rather in the metaphors of fiction, for example in novels and films.
Especially in Europe but also in many other parts of the world, adherence to a religion has strongly declined, and therefore the shared view of morality and human nature which religious authorities previously provided is no longer accepted.
Yet researchers often cannot avoid altogether being drawn into disputes about national sentiments, sometimes making it difficult to stay neutral, detached and objective.