Minimal gains for minimal pairs: Difficulty in learning similar-sounding words continues into preschool.

A critical indicator of spoken language knowledge is the ability to discern the finest possible distinctions that exist between words in a language-minimal pairs, for example, the distinction between the novel words beesh and peesh. Infants differentiate similar-sounding novel labels like "bih" and "dih" by 17 months of age or earlier in the context of word learning. Adult word learners readily distinguish similar-sounding words.

Perceptual flexibility in word learning: Preschoolers learn words with speech sound variability.

Children's language input is rife with acoustic variability. Much of this variability may facilitate learning by highlighting unvarying, criterial speech attributes. But in many cases, learners experience variation in those criterial attributes themselves, as when hearing speakers with different accents.