Investigators have uncovered evidence for phonological learning biases: biases inherent in learners that favor certain language phonologies over others (eg, Wilson 2006, Finley 2012, Moreton and Pater 2012, Hayes and White 2013, McMullin and Hansson 2014, White 2014). To what extent can a learning bias be defied in language? This question bears directly on the theory of phonological learning, as it addresses the limits of learner capability. A growing family of findings suggests that learners tend to favor phonological constraints that are morphosyntactically general—that is, obeyed by at least several morphemes, or in multiple or all grammatical contexts. That phonological alternations are typically corroborated by the phonotactics of a given language was observed as early as Chomsky and Halle 1968 and Kenstowicz and Kisseberth 1977, but the generalizing tendency just mentioned has also been observed in a number of recent corpus studies. Martin (2007, 2011), Shih and Zuraw (2018), and Breiss and Hayes (2019) observe cases of grammatical “leaking,” in which strong phonotactic restrictions tend to manifest across word boundaries or compound boundaries, or affect the choice between grammatical constructions. Chong (2017) found that certain alternations purported to be apparent derived-environment effects are just that—merely apparent. For example, though Korean t-palatalization triggered by high front vocoids was previously proposed to constitute a derived-environment effect because [ti]-sequences exist in some roots, Chong showed that such sequences are highly underattested in the Korean lexicon. Generalization effects have also been borne out in artificial-language-learning experiments: Myers and Padgett (2014) found that participants generalize a phrase-final devoicing pattern to the word-final domain without exposure to unambiguous evidence; Chong (2017) found that participants more readily learned a suffixal harmony alternation when they were exposed to higher rates of root harmony, corroborating proposals that phonotactic generalizations assist in acquiring alternations (eg, Tesar and Prince 2003, Hayes 2004, Jarosz 2006).

In light of these findings, Martin (2011) and Chong (2017) propose learning models whereby whenever the learner weights positively a structure-specific constraint (eg, applying only across a suffix boundary), it gives positive weight to an analogous structure-insensitive constraint, leading to the generalizing tendency. If there were to exist an alternation that applies consistently in a constrained morphosyntactic context without even an analogous statistical tendency in phonotactics to accompany it, then that would complicate our understanding of learners’ preference for morphosyntactically general pat-