The interrelatedness between infants' communicative gestures and lexicon size: A longitudinal study

- The number of gestures at 0;9 and 1;0 predicted word comprehension 3 months later.
- The number of gestures at 0;9 predicted word production at 1;0.
- Lexicon size did not predict the number of communicative gestures at any time point.

Research has shown a close relationship between gestures and language development. In this study, we investigate the cross-lagged relationships between different types of gestures and two lexicon dimensions: number of words produced and comprehended. Information about gestures and lexical development was collected from 48 typically developing infants when these were aged 0;9, 1;0 and 1;3. The European Portuguese version of the MacArthur-Bates Communicative Development Inventory: Words and Gestures (PT CDI:WG) was used. The results indicated that the total number of actions and gestures and the number of early gestures produced at 0;9 and at 1;0 year predicted the number of words comprehended three months later. Actions and gestures' predictive power of the number of words produced was limited to the 0;9-1;0 year interval. The opposite relationship was not found: word comprehension and production did not predict action and gestures three months later. These results highlight the importance of non-verbal communicative behavior in language development.