STAGE 1

When children learn their first language, they start speaking out loud to communicate with other children and with adults. This is the first stage of inner speech development, which is also known as the external dialogue stage. 

For example, Lenny, a preschool student, may say “Stop!” when poked too many times by his friend Bob.

STAGE 2

As children practice their speaking and listening skills more and more, they transition into stage 2 of the developmental model: private speech. This stage, on average, begins around the age of 3-4. In this second stage, children will start speaking to themselves out loud, engaging in self-regulation, or guidance they give themselves, sounding much like a scolding or supportive adult as they comment on their current activity. 

For example, Lenny may build a sandcastle in the sandbox and comment out loud “Good job!” to himself for his great building work.

STAGE 3

Once children begin thinking silently to themselves about tasks such as math, reading, or writing, they have entered stage 3 of the model: expanded inner speech. Expanded inner speech develops around the age 6-7, it focuses on activities happening in the present or in the future, and it has been compared to a top-down process (another top-down process is perception, when our brain organizes data to create a conclusion) since brain scans of expanded inner speech use similar regions of the brain. 

For example, Lenny, now in first grade, struggles through a math problem: One plus one equals what again? he thinks. I’ll hold up one finger for each one… oh right, two.

STAGE 4

The final stage of inner thought, condensed inner speech, is spontaneous and unconscious. It is ungrammatical, fast, and reflects the thinker’s current experience. This process resembles bottom-up processing in brain scans. 

For our final stage, Lenny has grown up and is a financial analyst at his friend Bob’s company. As he thinks about preparing for his big presentation to a client, an excerpt from his inner speech looks something like this: forgotkeyswalletohno gotta calculate profit margins slidesnotpretty howfix?  This example also demonstrates that as children grow into adults, their inner speech often becomes more and more abbreviated.

A note about the last two stages: Vygotsky had these two stages combined, but recent research by the guy from the YouTube video in the last section, Fernyhough, has suggested that we should have them as two separate stages.