This article summarizes the results of two experiments that use artificial grammar learning in order to test proposed phonological universals. The first universal involves limits on precedence-modification in phonological representations, drawn from a typology of ludlings (language games). It is found that certain unattested precedence-modifying operations in ludlings are also dispreferred in learning in experimental studies, suggesting that the typological gap reflects a principled and universal aspect of language structure. The second universal involves differences between vowels and consonants, and in particular, the fact that phonological typology finds vowel repetition and harmony to be widespread, while consonants are more likely to dissimilate. An artificial grammar task replicates this bias in the laboratory, suggesting that its presence in natural languages is not due to historical accident but to cognitive constraints on the form of linguistic grammars.