Nonce words show that Russian yer alternations are governed by the grammar

of alternating vowels is partially predictable: only mid vowels delete, but even mid vowels cannot delete in some contexts. We report on two nonce word studies ask-ing Russian speakers to rate paradigms in which a vowel was deleted. The ratings strongly correlated with the quality of the vowel: deletion of mid vowels was rated higher than deletion of high and low vowels. We also found that deletion in certain syllabic contexts was rated as ungrammatical: deletion cannot affect words that have a complex coda, and it cannot create clusters with a medial sonorant. Finally, deletion in disyllables was rated higher than deletion in monosyllables, reflecting the trends in the lexicon. These results suggest that even for this lexically-restricted alternation, speakers have formed a phonological generalization