The present study investigated the moderating role of early communicative pointing on the developmental trends of word comprehension and production over the second year of life. Seventy-seven infants were involved in an experimental pointing task (T-POINT) in sessions at 9 and 12 months, and the MB-CDI questionnaire was filled in by their parents at 15, 18 and 24 months. Based on the age at which the infants were seen to use pointing, they were classified into three groups: the 'Early' pointers, who first pointed during the 9-month session; the 'Typical' pointers, who first pointed in the 12-month session; and the 'Late' pointers, who never pointed in either of the sessions. Using multilevel modelling, we traced the developmental trajectories and individual differences for the two lexical domains of word comprehension and production according to the three pointing groups. The main results showed that compared to the Typical pointers: (i) the Early pointers were faster for word comprehension development, and were similar for word production; (ii) the Late pointers showed lexical delay before 18 months for word comprehension, and between 18 and 24 months for word production. These data are discussed in light of the different roles of early pointing on receptive compared to expressive vocabulary development.
Keywords: MB-CDI; developmental trajectories; individual differences; infancy; moderating effects; multilevel modelling; pointing gesture; word comprehension and production.