The intentionality model and language acquisition: engagement, effort, and the essential tension in development.

The purpose of the longitudinal research reported in this Monograph was to examine language acquisition in the second year of life in the context of developments in cognition, affect, and social connectedness. The theoretical focus for the research is on the agency of the child and the importance of the child's intentionality for explaining development, rather than on language as an independent object. The model of development for the research is a Model of Intentionality with two components: the engagement in a world of persons and objects that motivates acquiring a language, and the effort that is required to express and articulate increasingly discrepant and elaborate intentional state representations. The fundamental assumption in the model is that the driving force for acquiring language is in the essential tension between engagement and effort for linguistic, emotional, and physical actions of interpretation and expression. Results of lag sequential analyses are reported to show how different behaviors--words, sentences, emotional expressions, conversational interactions, and constructing thematic relations between objects in play--converged, both in the stream of children's actions in everyday events, in real time, and in developmental time between the emergence of words at about 13 months and the transition to simple sentences at about 2 years of age. Patterns of deviation from baseline rates of the different behaviors show that child emotional expression, child speech, and mother speech clearly influence each other, and the mutual influences between them are different at times of either emergence or achievement in both language and object play. The three conclusions that follow from the results of the research are that (a) expression and interpretation are the acts of performance in which language is learned, which means that performance counts for explaining language acquisition; (b) language is not an independent object but is acquired by a child in relation to other kinds of behaviors and their development; and (c) acquiring language in coordination with other behaviors in acts of expression and interpretation takes work, so that acquiring language is not easy.