Abstract
The development of prelinguistic communication in typically developing infants is marked by changes in complexity as well as frequency, yet most measures focus on frequency. In the current study we used the Communication Complexity Scale (CCS) to measure prelinguistic complexity of typically developing infants in a cross-sectional sample of 6-, 8-, 10- and 12-month-olds (N = 204) during semi-structured play interaction. For each toy/interactive episode, infants' highest level of communication complexity (ranging from 0 for no response to 12 for multi-word verbalization), for both joint attention (i.e., social) and behavior regulation (e.g., requesting) functions, was scored. In addition, the same interaction was coded for frequency of all prelinguistic communication acts. Results of multivariate models indicated age-related differences in prelinguistic complexity. Measures of prelinguistic complexity and frequency evidenced moderate to strong correlations, with age-related differences by function (joint attention and behavior regulation). Significant associations with parent-report communication questionnaires were observed for both complexity and frequency measures. Results indicate that evaluating complexity of infant preverbal communication skill with the CCS is a valuable approach that can meaningfully index developmental differences in prelinguistic and early linguistic communication.