DePaulo B M, Coleman L M
J Pers Soc Psychol. 1986 Nov;51(5):945-59. doi: 10.1037//0022-3514.51.5.945.
Speech addressed to different categories of listeners was examined in a study in which undergraduate women taught a block design task to either a 6-year-old child, a retarded adult, a peer who spoke English as a second language (foreigner), or a peer who was an unimpaired native speaker of English. The speech addressed to children differed from the speech addressed to native adults along every major dimension that emerged in this study: It was clearer, simpler, and more attention maintaining, and it included longer pauses. Speech addressed to retarded adults was similar in numerous ways to the speech addressed to 6-year-olds; in some ways (e.g., repetitiveness), it was even more babyish. However, speech to the retarded adults did differ in timing from the other styles of speaking in that it included fewer and somewhat shorter pauses. Speech addressed to foreigners was more repetitive than speech addressed to native speakers, but in all other ways it was very similar. There was some evidence that speakers fine-tuned their communications to the level of cognitive and linguistic sophistication of their particular listener; for example, speakers addressing the more sophisticated foreigners (relative to those addressing the less sophisticated foreigners) used speech that included fewer devices for clarifying, simplifying, and maintaining the listeners' attention. We discuss the hypothesis that baby talk (the speech addressed to children) is a prototypical special speech register from which other special registers are derived.
