Te Mental Lexicon 2:2 (2007), 2c–8. issn 1871–1340 / e-issn 1871–1375 © John Benjamins Publishing Company Te dislike of regular plurals in compounds Phonological familiarity or morphological constraint?* Iris Berent and Steven Pinker Department of Psychology, Florida Atlantic University / Department of Psychology, Harvard University English speakers disfavor compounds containing regular plurals compared to irregular ones. Haskell, MacDonald and Seidenberg (2003) attribute this phenomenon to the rarity of compounds containing words with the phonologi- cal properties of regular plurals. Five experiments test this proposal. Experi- ment 1 demonstrated that novel regular plurals (e.g., loonks-eater) are disliked in compounds compared to irregular plurals with illicit (hence less frequent) phonological patterns (e.g., leevk-eater, plural of loovk). Experiments 2–3 found that people show no dispreference for compounds containing nouns that merely sound like regular plurals (e.g., hose-installer vs. pipe-installer). Experiments 4–5 showed a robust effect of morphological regularity when phonological familiar- ity was controlled: Compounds containing regular plural nonwords (e.g., gleeks- hunter, plural of gleek) were disfavored relative to irregular, phonologically-iden- tical, plurals (e.g., breex-container, plural of broox). Te dispreference for regular plurals inside compounds thus hinges on the morphological distinction between irregular and regular forms and it is irreducible to phonological familiarity. Keywords: compound, inflection, morphology, phonology In explaining patterns of language, it is virtually impossible to avoid couching generalizations in terms of grammatical categories such as noun, verb, adjective, phrase, clause, word, root, stem, and suffix. Virtually all theories of grammar in- voke productive combinatorial rules that manipulate variables or symbols for such categories (e.g., Chomsky, 1980; Prince & Smolensky, 1993/2004). In contrast, connectionist models have tried to account for certain phenomena of language by associating sounds, meaning elements, or both according to their statistics in the language, with no representations of grammatical categories (e.g., Rumelhart & McClelland, 1986).