Infants generalize from just (the right) four words

•11-month-olds learn a phonological rule from just 4 words.•Learning is influenced by the degree of potential conflicting generalization.•Infants are not insurmountably biased to generalize based on phonetic features. Infants in the lab can generalize from 2min of language-like input. Given that infants might fail to fully encode so much input, how many examples do they actually need? And if infants only encode a subset of their input at one time, does generalization change when that subset supports multiple generalizations? Exp. 1 asked whether 11-month-olds generalize the relation between two consonants in a word when just four input words provided non-conflicting vs. partially conflicting support for a phonological feature-based generalization. Infants learned under both conditions, although the latter appears to be more difficult. Exp. 2 asked whether infants’ robust learning reflects a bias toward feature-based generalizations. Infants failed to generalize when input provided completely conflicting support for two generalizations. Together, the data suggest that infants are able to generalize from much less input than previously observed, but generalization depends on the specific subset of the input they encounter.