In this paper, we analyse spatial variation in the Japanese dialectal lexicon by assembling a set of methodologies using theories in variationist linguistics and GIScience, and tools used in historical GIS. Based on historical dialect atlas data, we calculate a linguistic distance matrix across survey localities. The linguistic variation expressed through this distance is contrasted with several measurements, based on spatial distance, utilised to estimate language contact potential across Japan, historically and at present. Further, administrative boundaries are tested for their separation effect. Measuring aggregate associations within linguistic variation can contrast previous notions of dialect area formation by detecting continua. Depending on local geographies in spatial subsets, great circle distance, travel distance and travel times explain a similar proportion of the variance in linguistic distance despite the limitations of the latter two. While they explain the majority, two further measurements estimating contact have lower explanatory power: least cost paths, modelling contact before the industrial revolution, based on DEM and sea navigation, and a linguistic influence index based on settlement hierarchy. Historical domain boundaries and present day prefecture boundaries are found to have a statistically significant effect on dialectal variation. However, the interplay of boundaries and distance is yet to be identified. We claim that a similar methodology can address spatial variation in other digital humanities, given a similar spatial and attribute granularity.

In this paper we analyse spatial variation in Japanese dialectal lexicon by assembling a set of methodologies using theories in variationist linguistics and GIScience, and tools used in historical GIS. Based on historical dialect atlas data, we calculate a linguistic distance matrix across survey localities. The linguistic variation expressed through this distance is contrasted with several measurements, based on spatial distance, utilised to estimate language contact potential across Japan, historically and at present. Further, administrative boundaries are tested for their separation effect. Measuring aggregate association within linguistic variation can contrast previous notions of dialect area formation by detecting continua. Depending on local geographies in spatial subsets, great circle distance, travel distance and travel times explain a similar proportion of the variance in linguistic distance despite the limitations of the latter two. While they explain the majority, two further measurements estimating contact have lower explanatory power: least cost paths modelling contact before the industrial revolution, based on DEM and seafaring, and a linguistic influence index based on settlement hierarchy. Historical domain boundaries and present day prefecture boundaries are found to have a statistically significant effect on dialectal variation. However, the interplay of boundaries and distance is yet to be identified. We claim that a similar methodology can address spatial variation in other digital humanities, given a similar spatial and attribute granularity.

<p><strong>Abstract.</strong> Since the end of the 19th century in Japan, the official language policy enforced using Standard Japanese, based on the variety spoken in Tokyo (formerly Edo), in all official situations and in schools. Since then, Japanese dialects have been dwindling and ‘flattening’ (i.e., they retain less regional variation). Nevertheless, differences of language varieties keep being important topics and they reinforce the feeling of belonging and group formation in Japan, similarly to most languages with dialects. This study explores the spatial patterns in Japanese lexical variation based on digitised dialectal survey data (using the Linguistic Atlas of Japan) and presents first results of a dialectometric analysis, quantifying a number of factors assumed to affect lexical variation in Japanese.</p>

We assemble a set of methodologies using theories in variationist linguistic and GIScience, and tools used in historical GIS to analyse spatial variation in Japanese dialectal lexicon. Based on historical dialect atlas data, we calculate a linguistic distance matrix across survey localities. The linguistic variation expressed through this distance is contrasted with several distance based measurements utilised to estimate the potential of language contact across Japan historically and at present. Besides, administrative boundaries are tested for their separation effect. Aggregate association measures within linguistic variation can challenge previous notions of dialect area formation. Depending on local geographies in spatial subsets, great circle distance, travel distance and travel times explain a similar proportion of the variance in dialectal variation despite the limitations of the latter two. While they explain the majority, two further contact estimations have lower explanatory power: least cost paths implemented to model contact before the industrial revolution, based on DEM and seafaring, and a linguistic influence index based on the law of gravity. Historical domain boundaries and present day prefecture boundaries are found to have a substantial effect on dialectal variation. However, the interplay of boundaries and distance is yet to be identified. We claim that a similar methodology can address spatial variation in other digital humanities, given a similar spatial and attribute granularity.