Gesture and speech are integrated in adult communication, and growing evidence suggests that their coordination begins early in infancy. However, the developmental processes through which motor and vocal behaviors evolve into communicative acts remain insufficiently understood. This longitudinal study examines the frequency and developmental trajectories of spontaneous movements, rhythmic movements, and gestures—produced both independently and in coordination with vocalizations— during naturalistic triadic interactions (adult-infant-object). Nine infants (2–12 months) were observed monthly and analyzed through fine-grained microanalytic coding using ELAN. Communicative development was also assessed using the Spanish version of the MacArthur–Bates inventory. Results showed a decline in spontaneous movements after the first trimester, an inverted U-shaped pattern for rhythmic movements with a peak between 6 and 9 months, and a rise in gestures in the final trimester of the first year. Multimodal combinations were infrequent and remained stable across age. Only rhythmic movement frequency correlated with productive vocabulary at 9 months. These findings suggest that expressive development during infancy involves a gradual reorganization of motor behaviors, with distinct temporal and communicative profiles. The limited presence of stable multimodal patterns likely reflects an early phase in the emergence of multimodal coordination. By capturing these early forms of expressivity, the study sheds light on how specific motor behaviors—particularly rhythmic movements—contribute to the foundation of intentional and coordinated communication.
Azagra et al. (Wed,) studied this question.