Is phonological learning subject to the same inductive biases as learning in other domains? Previous studies of non-linguistic learning found that intra-dimensional dependencies (between two instances of the same feature) were learned more easily than inter-dimensional ones. This study compares implicit learning of intra- and inter-dimensional phonotactic dependencies. A series of six unsupervised implicit-learning experiments shows that a pattern based on agreement between two instances of the same feature is easier to learn than one based on correlation between instances of two different features. The results are interpreted as evidence for domain-general restrictions on the form of domain-specific learning primitives. (Contains 20 tables and 2 figures.)