Having heard that Scandinavians can understand each others’ languages, clients sometimes ask us for a combined Danish/Norwegian/Swedish translation. Such translations tend to appear on cosmetics packaging where space is at a premium. The idea is to first translate everything into e.g. Danish and then add any Norwegian and Swedish words with slashes where the reader would not understand the Danish. A hair conditioner bottle could thus say: “Bruksanvisning: Etter sjamponering, klem/krama ut overflødig vann/vatten fra håret”.
In linguistics, the phenomenon of speakers of related languages being able to understand each other without any study or excessive effort is called “mutual intelligibility”. Apart from the three Scandinavian languages, other such language groups are Serbian/Croatian/Bosnian and Galician/Portuguese/Spanish.
Intelligibility between languages can be asymmetric, with speakers of one understanding more of the other than speakers of the second understand of the first. Intelligibility is only characterised as “mutual” when it is relatively symmetric.
So, how well do Scandinavians really understand each others’ languages? During 2002–2005, Lars-Olof Delsing and Katarina Lundin Åkesson undertook a study funded by the Nordic Cultural Fund, where native speakers under the age of 25 were asked to participate in a test consisting of a video, listening comprehension and two written articles (available in Swedish here). The result showed that Swedish-speakers in Stockholm and Danish-speakers in Copenhagen have the greatest difficulty in understanding other Scandinavian languages.
Norwegian and Danish have similar vocabulary but a different sound system, whilst Norwegians and Swedes are helped by the similarity of their sound systems but struggle with the differences in vocabulary. Swedes and Danes struggle with differences in both. Danish differs the most between its spoken and written forms, consequently Swedes find the written form much more easy to understand than the spoken. In Norway, of the two variants of Norwegian, bokmål is closer to Danish while nynorsk has more in common with Swedish.