The development of vocabulary and grammar: a longitudinal study of European Portuguese speaking toddlers

The goals of this study were to analyze the growth and stability of vocabulary, mean length of the three longest utterances (MLLUw), and sentence complexity in European Portuguese-speaking children aged 1;4–2;6, to explore differences in growth as a function of personal and family-related variables, and to investigate the interrelationships among the three language dimensions. Fifty-one European Portuguesespeaking toddlers were longitudinally assessed at 1;4, 1;9, 2;1, and 2;6, through parent reports. Exponential growth models best described acquisition patterns during this period, but the vocabulary growth accelerated across the full age-range, whereas the growth of grammar dimensions accelerated mainly after 1;9. High variability was observed in the scores, but the toddlers’ relative positions were mostly stable over time. Gender approached significance as a predictor of vocabulary growth. Maternal educational level did not predict the growth of any of the three language dimensions. Both vocabulary and MLLUw predicted sentence complexity.This research was supported by European Regional Development Fund (FEDER) through the European program COMPETE (Operational Programme for Competitiveness Factors), under the National Strategic Reference Framework (QREN) - FCOMP-01-0124-FEDER-029556, by FCT (Fundação para a Ciência e a Tecnologia PTDC/MHC-PED/4725/2012), and by the Research Centre on Child Studies (CIEC-UM, reference POCI-01-0145-FEDER-007562). The first and fourth authors are also supported by grants SFRH/BPD/102549/2014 and SFRH/BD/86795/2012 from FCT