Purpose

This experiment examined English- or Spanish-learning preverbal (8–9 months, n = 32) and postverbal (12–14 months, n = 40) infants' learning of word–action pairings prior to and after the transition to verb comprehension and its relation to naturally learned vocabulary.

Method

Infants of both verbal levels were first habituated to 2 dynamic video displays of novel word–action pairings, the words /wem/ or /bæf/, spoken synchronously with an adult shaking or looming an object, and tested with interchanged (switched) versus same word–action pairings. Mothers of the postverbal infants were asked to report on their infants' vocabulary on the MacArthur–Bates Communicative Development Inventories (Fenson et al., 1994).

Results

The preverbal infants looked longer to the switched relative to same pairings, suggesting word–action mapping, but not the postverbal infants. Mothers of the postverbal infants reported a noun bias on the MacArthur–Bates Communicative Development Inventories; infants learned more nouns than verbs in the natural environment. Further analyses revealed marginal word–action mapping in postverbal infants who learned fewer nouns and only comprehended verbs (post–verb comprehension), but not in those who learned more nouns and also produced verbs (post–verb production).

Conclusions

These findings on verb learning from inside and outside the laboratory suggest a developmental shift from domain-general to language-specific mechanisms. Long before they talk, infants learning a noun-dominant language learn synchronous word–action relations. As a postverbal language-specific noun bias develops, this learning temporarily diminishes.