Lexical and orthographic distances between Germanic, Romance and Slavic languages and their relationship to geographic distance

When reading texts of different but closely related languages, intelligibility is determined among others by the number of words which are cognates of words in the reader’s language, and orthographic differences. Orthographic differences partly reflect pronunciation differences and therefore are partly a linguistic level. Dialectometric studies in particular showed that different linguistic levels may correlate with each other and with geography. This may raise the question of whether both lexical distance and orthographic distance need to be included in a model which explains written intelligibility, or whether both factors can even be replaced by geographic distance. We study the relationship between lexical and orthographic variation among Germanic, Romance and Slavic languages to each other and to geography. The lexical distance is the percentage of non-cognate pairs, and the orthographic distance is the average of the Levenshtein distances of the cognate pairs. For each language group we found a significant correlation between lexical and orthographic distances with a medium effect size. Therefore, when modelling written intelligibility preferably both factors are included in the model. We considered several measures of geographic distance where languages are located at the center or capital of the countries where they are spoken. Both as-the-crowflies distances and travel distances were considered. Largest effect sizes are obtained when correlating lexical distances with travel distances between capitals and when correlating orthographic distances with as-the-crow-flies distances between capitals. The results show that geographic distance may represent lexical and orthographic distance to some extent in a model of written intelligibility.