Isaac, five, is doing some homework at the kitchen table. He has been given some letter shapes to trace, and he is concentrating hard, working on the flicks and flourishes that link one letter to another. He is relaxed and happy, and enjoying the chance to show off what he has been learning at school. His little hands still find the pencil a handful, and the complexities of joined-up writing make this demanding work. I am not watching his hands, though, or the fine motor actions that drive his pencil lead across the page. I am watching his lips.
Have you ever been in a kindergarten classroom, or watched a first-grade class getting busy with a task? If so, you'll know that there is no such thing as quiet seatwork. It is not social chit-chat that adds to the decibel levels in these situations, so much as a different kind of speech. Give a child a puzzle to work on, and they will talk: not to their neighbors or their teachers, but to themselves. The more that psychologists investigate this phenomenon, the more convinced they become that the study of self-directed speech can add something important to our picture of how cognition works.
We call this phenomenon private speech. Piaget was the first to take it seriously as a issue in developmental psychology, but it is Vygotsky's explanation of it that attracts the most interest these days. Vygotsky argued that talking to yourself shapes thought. Thinking begins as a linguistic collaboration with other individuals, which gradually becomes internalized into a private dialogue with the self. When you see a child talking to herself during an episode of play or puzzle-solving, you are witnessing just such a private dialogue.
As development progresses, these private dialogues become steadily less noticeable to an external observer. Here's how I describe this process of internalization in my book
A Thousand Days of Wonder: A Scientist's Chronicle of His Daughter's Developing Mind
, where I describe Athena's persistent attempts to solve a jigsaw puzzle:
Since she brought a clattering conclusion to her first attempt, Athena's renewed application to her puzzle is proving to have a rather different feel. [...] The rich, mutually sensitive dialogue of a moment ago has been almost entirely appropriated by Athena. She is doing the elaborating for herself, such as making police car noises to accompany the placing of the car. She doesn't need Lizzie [her mother] to bring her attention repeatedly back to the task; she can keep her own self focused. And through it all she is talking: naming pieces, stating their destinations, asking questions and then answering them on her own. We are witnessing a new kind of thought taking shape, transforming from a shared, social activity to Athena's dialogue with herself. As thinking continues to move inwards-as it becomes ‘internalized'-she will be able to conduct these dialogues of thought completely silently. Like a pensive adult, she'll do it all in her head. Language will still be mediating her thinking, but it will be a new kind of language, the sort that only she will hear.
Researchers have been studying private speech in the laboratory, classroom, and other contexts for several decades now. A couple of months ago we published the first edited volume on this topic since Diaz and Berk's 1992 collection1. This was a great opportunity for me and my co-editors (Adam Winsler from George Mason University and Nacho Montero from the Universidad Autónoma of Madrid) to see what was going on in the field as a whole. Our contributors describe some fascinating findings on private speech in children and adults, in typical and atypical development, in the classroom and in the MRI scanner. You can read more about the resulting volume here.
1 R. M. Diaz and L. E. Berk (1992). Private Speech: From social interaction to self-regulation. Hillsdale, NJ: Lawrence Erlbaum Associates.