How well can intelligibility of closely related languages in Europe be predicted by linguistic and non-linguistic variables?

We measured mutual intelligibility of 16 closely related spoken languages in Europe. Intelligibility was determined for all 70 language combinations using the same uniform methodology (a cloze test). We analysed the results of 1833 listeners representing the mutual intelligibility between young, educated Europeans from the same 16 countries. Lexical, phonological, orthographic, morphological and syntactic distances were computed as linguistic variables. We also quantified non-linguistic variables (e.g. exposure, attitudes towards the test languages). Using stepwise regression analysis the importance of linguistic and non-linguistic predictors for the mutual intelligibility in the 70 language pairs was assessed. Exposure to the test language was the most important variable, overriding all other variables. Then, limiting the analysis to the prediction of inherent intelligibility, we analysed the results for a subset of listeners with no or little previous exposure to the test language. Linguistic distances, especially lexical distance, now explain a substantial part of the variance.