@article{KellerSchultz2014,
  author    = {Keller, Daniela Barbara and Schultz, J{\"o}rg},
  title     = {Word Formation Is Aware of Morpheme Family Size},
  doi       = {10.1371/journal.pone.0093978},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-112848},
  year      = {2014},
  abstract  = {Words are built from smaller meaning bearing parts, called morphemes. As one word can contain multiple morphemes, one morpheme can be present in different words. The number of distinct words a morpheme can be found in is its family size. Here we used Birth-Death-Innovation Models (BDIMs) to analyze the distribution of morpheme family sizes in English and German vocabulary over the last 200 years. Rather than just fitting to a probability distribution, these mechanistic models allow for the direct interpretation of identified parameters. Despite the complexity of language change, we indeed found that a specific variant of this pure stochastic model, the second order linear balanced BDIM, significantly fitted the observed distributions. In this model, birth and death rates are increased for smaller morpheme families. This finding indicates an influence of morpheme family sizes on vocabulary changes. This could be an effect of word formation, perception or both. On a more general level, we give an example on how mechanistic models can enable the identification of statistical trends in language change usually hidden by cultural influences.},
  language  = {en}
}
@article{SchultzKeller2013,
  author    = {Schultz, J{\"o}rg and Keller, Daniela Barbara},
  title     = {Connectivity, Not Frequency, Determines the Fate of a Morpheme},
  series = {PLoS ONE},
  journal   = {PLoS ONE},
  doi       = {10.1371/journal.pone.0069945},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-97039},
  year      = {2013},
  abstract  = {Morphemes are the smallest meaningful parts of words and therefore represent a natural unit to study the evolution of words. To analyze the influence of language change on morphemes, we performed a large scale analysis of German and English vocabulary covering the last 200 years. Using a network approach from bioinformatics, we examined the historical dynamics of morphemes, the fixation of new morphemes and the emergence of words containing existing morphemes. We found that these processes are driven mainly by the number of different direct neighbors of a morpheme in words (connectivity, an equivalent to family size or type frequency) and not its frequency of usage (equivalent to token frequency). This contrasts words, whose survival is determined by their frequency of usage. We therefore identified features of morphemes which are not dictated by the statistical properties of words. As morphemes are also relevant for the mental representation of words, this result might enable establishing a link between an individual's perception of language and historical language change.},
  language  = {en}
}