Achievement

A central view within cognitive science is that young children master highly subtle aspects of language surprisingly easily, but this remains controversial, and more up-to-date, interdisciplinary evidence is needed. Where English has only 'to be', Spanish has two verbs, 'estar' and 'ser', and adequately characterizing the difference has been a major challenge for linguists. But very few errors with these verbs appear in child speech, as shown by trainee Monica Lopez Gonzalez. Gathering new data in Mexico, she showed that children younger than 42 months did not yet *comprehend* the difference, although their *productions* showed correct use of both verbs as early as 30 months -- a reversal of the usual 'comprehension precedes production' pattern of child language. Through comprehensive formal syntactic and formal semantic analysis, Gonzalez showed that correct use requires quite different syntactic structures for the two verbs, and three different semantic structures just for 'ser'.