Using big data from examination results, we studied the impact of L1 to additional language (Ln) Dutch similarity measures on examination scores. Our conclusion is (1) that less L1-Ln language similarities return a higher complex Ln learning task, and (2) that similarity measures for different language components complement each other.
We studied the impact of L1 to additional language (Ln) Dutch similarity measures on the speaking test scores of more than 50,000 higher-educated adult learners of Dutch: lexical, morphological, and phonological similarity. Our hypotheses were that less L1-Ln language similarity returns a higher complex Ln learning task, and (2) that similarity measures for different language components complement each other. Lexical similarity was measured by an absolute measure that expresses branch lengths in a phylogenetic language tree based on expert cognacy judgements of words in Swadesh lists (Gray & Atkinson, 2003). Morphological similarity was a relative measure relating the properties of an L1 to the properties of an Ln (Ln Dutch) that is based on selected morphological features as described in WALS, used by Lupyan and Dale (2010). Phonological similarity was a relative measure, too, relating the new features for an L1 to the features of an Ln (Ln Dutch). This measure is based on selected phonological features as described in PHOIBLE (Moran, McCloy & Wright, 2014; Schepens, Jaeger & van Hout, 2019). The impact of the similarity measures on the acquisition of Dutch as an additional language was examined in immigrants from 49 mother tongue backgrounds, spoken in 74 countries, 20 of which were Indo-European and 13 non-Indo-European. We found that combining different similarity measures yielded an accumulative, unbiased, and fairly complete account of L1 differences in Ln Dutch speaking test scores. Using specific L1-Ln similarity measures for different language components means that complexity is relative, depending on the language pairs and the language components involved. To further test the applicability of these measures, (1) we analyzed the writing, listening, and reading test scores of these higher educated Ln learners, and (2) we analyzed another large L2 database on lower-educated adult learners of Dutch, for all four language modalities.
