Internal Monologue

Also known as interior monologue, inner voice, internal speech, or stream of consciousness.

Much of what people consciously report "thinking about" may be thought of as an internal monologue, a conversation with oneself. Some of this can be considered as speech rehersal, and it seems to be that the internal monologue is generally in the native language of the person concerned.

Discussion
In fiction, when one person reads the mind of another, it is often described as being able to hear this internal monologue as if it was said out loud.

If presented with a transcript purporting to be record of one's recent internal monologue, a person would be able to recognize the accuracy and inaccuracy in the transcript. Unfortunately for researchers no magic mind reading device exists that would allow us to produce such a transcript.

When children are taught to read out loud and then later taught to read quietly, they often subvocalize. This has lead to a discipline called Speed reading that attempts to suppress this. If one were able to pick up on this subvocalization it might lead to a transcript device.

In some conditions there is an uncertainty about what the source of these internal sentences is. Attribution for a recently produced internal sentence may lead to concerns over schizophrenia, hallucinations, or hearing voices. The religious practice of Zen attempts to quiet the internal voice by various means.

Inner speech is by nature a person's authentic set of expressions, revealed before internal censors can come into play, truly free speech. When an internal sentence crosses a societal taboo, it can be considered a thought crime, at least in certain fictional realms.

Production
In order to create internal speech, many of the various components of normal language production must come into play. The mental faculties that deal with semantics and syntax do just as much work in creating an internal sentence as they do in creating one for external use.

Consumption
The person creating the inner speech is also the sole consumer of the monologue. Propositions once created allow a person to consider their implications and formulate logical correlates.

Flow
Over a period of time the topic of a stream of conscious will wander. How the stream changes can be described as the flow. Various internal and external causes may affect the flow, including smells, music, and memories. Changes in the flow of consciousness can be logical or seemingly quite random. In the latter case, the subconscious may be at work.