There have been numerous research studies dedicated to the analysis of the development of language, but until only a few decades ago those dedicated to communication were relatively scarce. The 1980s witnessed an increase in studies on human communication considered as a social, interactive phenomenon (Dickson, 1981; Noizet, Bélanger, & Bresson, 1985). But social interaction does not account for the entirety of the communicative event. Communicative exchange requires the conjunction of a series of cognitive, linguistic, and social abilities, which are activated to differing degrees in the act of communicating (Shantz, 1983).
Within the vast domain of human communication, our specific interest concerns communicative processes in which cognitive, linguistic, and social abilities are closely related. The linguistic instrument occupies a privileged place, because it allows people to control their own behavior as encoders and decoders of their own messages (Flavell, 1981). Along these lines, an important body of research on public and private communicative functions can be found that starts from the classic studies on egocentric speech related by Piaget (1923/1962) and criticized by Vygotsky (1934/1987). Whereas Piaget did not assign this type of speech any useful function, Vygotsky stressed its importance in the control and progressive planning of behavior through a process of internalization. In this process of internalization, a barely audible or silent speech is produced that complicates a methodological approach. As a result, the taxonomies and procedures employed in order to study it have been both numerous and controversial (Frauenglass & Díaz, 1985; Frawley & Lantolf, 1986).