Young children often talk to themselves out loud. Indeed, there is a substantial literature on children's private speech demonstrating that verbal mediation in the form of overt self-directed speech is an important feature of children's engagement with the world (e.g., see edited volumes by Díaz & Berk, 1992, and Zivin, 1979). Adults, too, talk to themselves out loud – this in spite of the stigma often associated with private speech. In this regard, the American sociologist Irving Goffman (1981) reminds us that “in our society a taboo is placed on self-talk” (p. 81), a taboo whose existence could quite reasonably be expected to inhibit private speech in those (mostly adults) for whom this taboo has some authoritative value. Goffman notes that due to the taboo nature of self-talk, “it is mainly through self-observation and hearsay that one can find out that a considerable amount goes on” (p. 81). A small but growing empirical literature on adolescents' and adults' use of private speech – on its “persistence,” as our title indicates – appears to confirm this suspicion.

Our emphasis on the persistence of private speech already suggests a direction for our argument: namely, that of expanding the conventional Vygotskian view – perpetuated, implicitly if not explicitly, in almost all the contemporary literature on the subject – that private speech is limited to a particular developmental stage occurring during childhood.