Linguistic and non-linguistic factors affecting intelligibility across closely related varieties in Pentecost Island, Vanuatu

Mutual intelligibility between speakers of four related language varieties spoken in the northern half of the island of Pentecost in Vanuatu (Raga, Suru Kavian, Suru Rabwanga and Suru Mwerani) is investigated. Raga is a separate language spoken in the northernmost part of Pentecost and is intelligible to varying degrees to speakers of the other three varieties. The other three varieties are considered dialects of the same language, Apma. However, intelligibility between the dialects is asymmetric. Although Suru Kavian speakers claim to understand Suru Rabwanga and Suru Mwerani without difficulty, speakers of the latter two varieties maintain that they have significant problems understanding Suru Kavian. These claims are supported by the results. To explain the intelligibility results they were correlated with quantitative measures of linguistic (phonetic and lexical distances) and non-linguistic (geographical distances and a measure of exposure) factors that may play a role in mutual intelligibility.