And while marked syllables, such as lbif, are typically ones that are also harder to articulate and perceive on purely phonetic grounds, by hypothesis, grammatical markedness constraints are independently represented in the grammar, irreducible to their analog phonetic precursors ( de Lacy 2006b). Consequently, marked structures are less likely to emerge in typology, they are disfavored as the output of active phonological alternations, and they are more difficult to master in language acquisition. Because the variant lbif incurs a more severe violation of markedness constraints, grammars are less likely to admit this marked variant compared to its unmarked counterpart, blif. Markedness constraints, for example, disfavor syllables such as lbif over blif. In this view, all phonological grammars include a universal set of grammatical well-formedness restrictions called markedness constraints. Others, however, assert that productivity might be constrained, in part, by grammatical principles that are potentially specific to language (e.g., Jakobson 1968 Prince & Smolensky 1993/2004 de Lacy 2006a).

Some authors attribute linguistic generalizations to domain-general mechanisms, including statistical learning, articulatory and auditory preferences (e.g., Blevins 2004 Bybee & McClelland 2005 MacNeilage 2008). But while the productivity of language is widely recognized, its source is contentious. Infants as young as nine months of age, for instance, favor syllables like blif over lbif despite no experience with either (e.g., Friederici & Wessels 1993). A large body of research demonstrates the sensitivity of young children and adults to the sound-pattern of novel linguistic forms that they have never heard before.

Sonority hierarchy example