The ability to generalize previous knowledge to new contexts is a key aspect of human cognition and relational learning. A well-known learning maxim is that breadth of training predicts "breadth of transfer." When examples vary in their surface features, this provides evidence that only the common relational structure is relevant. However, there is some evidence suggesting that the above maxim may not apply well in early relational learning. Here, we present a further test whether the maxim holds for young infants. We find that 3-month-old infants perform better with a narrow, perceptually similar training set than with a broad, perceptually variable set. We argue that lower-level perceptual similarities can prompt comparison processes that facilitate relational abstraction. These findings cohere with research arguing relational learning depends on relational alignment. [This paper was published in: M. Goldwater, F. K. Anggoro, B. K. Hayes, and D. C. Ong (Eds.), "Proceedings of the 45th Annual Conference of the Cognitive Science Society." Cognitive Science Society, 2023, pp. 208-215.]