Morphological Complexity outside of Universal Grammar1

There are many logical possibilities for marking morphological features. However only some of them are attested in languages of the world, and out of them some are more frequent than others. For example, it has been observed (Sapir 1921; Greenberg 1957; Hawkins & Gilligan 1988) that inflectional morphology tends to overwhelmingly involve suffixation rather than prefixation. This paper proposes an explanation for this asymmetry in terms of acquisition complexity. The complexity measure is based on the Levenshtein edit distance, modified to reflect human memory limitations and the fact that language occurs in time. This measure produces some interesting predictions: for example, it predicts correctly the prefix-suffix asymmetry and shows mirror image morphology to be virtually impossible. 1We thank Chris Brew, Beth Hume, Brian Joseph, John Nerbonne and 3 anonymous reviewers from the Cognitive Science Journal for valuable feedback on various versions of this paper. We also thank to Mary Beckman and Shari Speer. Jirka Hana & Peter W. Culicover. Morphological Complexity Outside of Universal Grammar. OSUWPL, Volume 58, Spring 2008, pp. 85–109. 86 JIRKA HANA & PETER W. CULICOVER