Jean Piaget, a pioneering Swiss psychologist, observed three 6-year-olds in 1921-22 at the Institute Rousseau. The children were in an open-classroom setting, and adults transcribed their speech, then listed it in numbered sentences for analysis. The observers noted that in many cases, the children expressed out loud what they were doing, with little need for a response from their companions. In fact, they might not respond to a change of subject from someone else. They believed that the children's conversation could be divided into two categories: egocentric speech and socialized speech.
Egocentric speech can be repetitive phrases, similar to echolalia, or repetitions of phrases, heard in toddler speech, or it can be a monologue of ideas that requires no listener. A child age 5 to 7 might be heard describing what his toys are doing. Piaget noted that this verbalization is similar to the way people who live alone might verbalize their activities. According to an article at Psych Central, talking to yourself as a sign of sanity -- it helps you make decisions. Modern psychology texts describe the behavior Piaget observed as parallel play. The Child Development Institute places this behavior as being normal for children ages 3 through late kindergarten.
Socialized speech involves more of a give-and-take between people. In "The Language and Thought of the Child," Piaget stated that early language denotes cries of desire. He mentions the word "mama" as coming from a labial motion having to do with sucking. He attributed his information to Sabina Spielrein, who was the first patient of Carl Jung, the father of analytical psychology.
Piaget stated in his notes that only about 14 percent of the children's conversation was interactive responses to each other. However, he also noted that before attending school, the children involved in the study had not been accustomed to other children. Piaget placed questions in a special category of conversation. He felt that the children were not seeking an actual explanation when they asked ritualistic questions, such as "Why?" and that they had not really developed sufficient mental complexity to understand causation. Piaget found that more than half of the children's conversation was egocentric speech, indicating to him that much of these 6-year-olds' attention was centered upon themselves and their own concerns.
In the final chapter of "The Language and Thought of the Child," Piaget summed up his study by saying he believed that adults should understand that children are far more egocentric than adults, and that they interact differently even when behaving socially. He added that adults should not expect young children to form social groups, but should expect a gathering of children to be very noisy because the youngsters would all be talking at once. He stated that even when an adult is engaged in an individual pursuit, he still thinks socially. Whereas a child, even when engaged in what appears to be a social activity, still functions individually.