Elamur Research⌕
☰
home / papers / 2026 / Improving phonological distance measures for signs: the CatFormCompare tool

Improving phonological distance measures for signs: the CatFormCompare tool

Paper · 2026 · Hope E. Morgan, Amy Isard and Anh Dang

Summary

Sign language phonology lacks a notation precise enough to find minimal pairs automatically. A minimal pair is two signs with different meanings that differ in only one form value. Levenshtein-style edit distances assume sequential segments, but sign features are mostly simultaneous and contrast mainly by substitution. A naive field-by-field match/no-match comparison also fails because it ignores dependencies between features; for example, an ending handshape may be predictable from the type of handshape change. The authors propose a two-part pipeline. Signs are first encoded as SL CatForm strings, and then CatFormCompare, a Python tool, compares pairs of strings while applying "conditionalities" that model these dependencies, so only linguistically meaningful differences are counted. The pipeline was evaluated on 1,880 Kenyan Sign Language (KSL) signs, with 449 previously identified same-signer minimal pairs serving as ground truth. It works in principle but still misses some pairs, notably location contrasts, and needs refinement. The work matters because it grounds phonological distance in actual linguistic structure rather than in artefacts of a coding system, and it gives schema designers a feedback loop.

Key points

  • The SL CatForm coding schema has 42 categorical variables (0–41), each value coded as one or two ASCII characters. It is based on the Dependency Model with changes inspired by the Prosodic Model, and it has previously been applied to KSL and Israeli Sign Language.
  • Evaluation data: 1,880 KSL signs and 449 minimal pairs. Only pairs produced by the same signer were kept, so each pair reflects a single grammar.
  • Example conditionality: handshape contours vs. handshape contrasts (variables 7, 8 and 32). In a closing contour, the contrast is in the starting handshape, while a true contrast can sit in the ending handshape.
  • The tool, coding schema and a KSL data sample are released via the Hamburg University Research Data Repository (doi:10.25592/uhhfdm.18534).
  • Planned next steps: diagnose mismatches, especially missed location pairs; expand the diagnostic test set; and rethink how orientation is coded.

Our summary of the paper, in our own words — not its text. The work belongs to its authors; read it at the links above.

 Institutions

🎓Universität HamburgHamburg · Germany79 works · 5,422 citations🎓Utrecht UniversityUtrecht · Netherlands39 works · 1,603 citations

 Fields, topics and concepts

📚 Shelves 7The field of science this work belongs to (OpenAlex fields).Computer Science · 16,667 worksArts and Humanities · 16,039 worksLanguage and Linguistics · 15,891 worksPsychology · 1,552 worksExperimental and Cognitive Psychology · 870 worksDevelopmental and Educational Psychology · 499 worksHuman-Computer Interaction · 141 works

Cite

Cite as Hope E. Morgan, Amy Isard and Anh Dang. 2026. Improving phonological distance measures for signs: the CatFormCompare tool. Proceedings of the LREC 2026 12th Workshop on the Representation and Processing of Sign Languages: Language in Motion.

The paper itself, not this page. BibTeX from the library's record of the work. DOI 10.63317/3etemouixntr

@inproceedings{morgan2026improving,
  title = {{Improving phonological distance measures for signs: the CatFormCompare tool}},
  author = {Hope E. Morgan, Amy Isard and Anh Dang},
  booktitle = {Proceedings of the LREC 2026 12th Workshop on the Representation and Processing of Sign Languages: Language in Motion},
  year = {2026},
  doi = {10.63317/3etemouixntr},
  url = {https://doi.org/10.63317/3etemouixntr}
}

References

22 references, 1 of them with a card of ours. ↗ leads to the work, «find» searches for one we have no id for yet.

  1. Robbin Battison. 1978. Lexical Borrowing in American Sign Language. Linstok Press, Silver Spring, MD. find
  2. Carl Börstell, Onno Crasborn, and Lori Whynot. 2020. Measuring lexical similarity across sign languages in Global Signbank. In Proceedings of the LREC2020 9th Workshop on the Representation and Processing of Sign Languages, pages 21–26, Marseille, France. European Language Resources Association (ELR… find
  3. Diane Brentari. 1989. A Prosodic Model of Sign Language Phonology. MIT Press, Cambridge, MA. find
  4. Naomi K. Caselli, Karen Emmorey, and Ariel M. Cohen-Goldberg. 2021. The signed mental lexicon: Effects of phonological neighborhood density, iconicity, and childhood language experience. Journal of Memory and Language, 121:104282. find
  5. Rachel Elizabeth Channon. 2002. Phonological Representations and Temporal Sequencing in ASL and Other Sign Languages. Ph.D. thesis, University of Maryland, College Park. find
  6. David P. Corina. 1993. To branch or not to branch: Underspecification in ASL handshape contours. In Geoffrey R. Coulter, editor, Phonetics and Phonology: Current Issues in ASL Phonology, pages 63–95. Academic Press. find
  7. Bart de Boer, Wendy Sandler, and Simon Kirby. 2012. New perspectives on duality of patterning: Introduction to the special issue. Language and Cognition, 4:251–259. find
  8. Thomas Hanke. 2004. HamNoSys – representing sign language data in language resources and language processing contexts. In Proceedings of the LREC2004 Workshop on the Representation and Processing of Sign Languages: From Sign-Writing to Image Processing. Information techniques and their implications… find
  9. Lisa Loy and Hope E. Morgan. 2026. Hns2cf: A mapping tool from hamnosys to sl catform. In Proceedings of the LREC-COLING 2026 12th Workshop on the Representation and Processing of Sign Languages: Language in Motion, Palma, Mallorca (Spain). ELRA Language Resources Association (ELRA).
  10. Mark Alan Mandel. 1981. Phonotactics and Morphophonology in American Sign Language. Ph.D. thesis, University of California, Berkeley. find
  11. Aurora Martinez del Rio, Casey Ferrara, Sanghee J. Kim, Emre Hakgüder, and Diane Brentari. 2022. Identifying the correlations between the semantics and the phonology of American Sign Language and British Sign Language: A vector space approach. Frontiers in Psychology, 13:806471. for sign languages.… find
  12. Hope E. Morgan, Wendy Sandler, Rose Stamp, and Rama Novogrodsky. 2022. ISL-LEX v.1: An online lexical resource of Israeli Sign Language. In Proceedings of the LREC2022 10th Workshop on the Representation and Processing of Sign Languages: Multilingual Sign Language Resources, pages 148–153, Marseille… find
  13. Jason Parks. 2011. Sign language word list comparisons: Toward a replicable coding and scoring methodology. Master’s thesis, University of North Dakota. find
  14. Lorna Grace Rozelle. 2003. The Structure of Sign Language Lexicons: Inventory and Distribution of Handshape and Location. Ph.D. thesis, University of Washington. find
  15. Wendy Sandler. 1989. Phonological Representation of the Sign: Linearity and Nonlinearity in American Sign Language. De Gruyter Mouton, Berlin, New York. find
  16. Yue Sun and David Poeppel. 2023. Syllables and their beginnings have a special role in the mental lexicon. Proceedings of the National Academy of Sciences, 120(36):e2215710120. find
  17. Els van der Kooij. 2002. Phonological categories in Sign Language of the Netherlands: The role of phonetic implementation and iconicity. LOT Publications, Leiden, Netherlands. find
  18. Andrew Wedel, Abby Kaplan, and Scott Jackson. 2013. High functional load inhibits phonological contrast loss: A corpus study. Cognition, 128(2):179–186. find
  19. Shi Yu, Carlo Geraci, and Natasha Abner. 2018. Sign languages and the online world online dictionaries & lexicostatistics. In 11th International Conference on Language Resources and Evaluation (LREC 2018), Miyazaki, Japan. European Language Resources Association (ELRA). find
  20. David McKee and Graeme Kennedy. 2000. Lexical comparison of signs from american, australian, british and new zealand sign languages. In Karen Emmorey and Harlan L. Lane, editors, The signs of language revisited: An anthology to honor Ursula Bellugi and Edward Klima. Psychology Press. find
  21. Hope E. Morgan. 2022. A Phonological Grammar of Kenyan Sign Language. De Gruyter Mouton, Berlin, Boston. find
  22. Hope E. Morgan. 2026. SL CatForm coding schema v.1: A field-based phonological coding find

Updated

↑ back to top

This page in Markdown → https://md.research.elamur.ai/free/en/papers/morgan-2026-improving-phonological-distance-measures-signs/