"One researcher... clocks inner speech at an average pace of 4,000 words per minute—10 times faster than verbal speech."

"And it’s often more condensed—we don’t have to use full sentences to talk to ourselves, because we know what we mean. But it does maintain many of the characteristics of dialogue. We may imagine an exchange with someone else, or we may just talk to ourselves. But that doesn’t mean it’s not a conversation. Our minds contain many different perspectives, and they can argue or confer or talk over each other. 'We are all fragmented... There is no unitary self. We are all in pieces, struggling to create the illusion of a coherent "me" from moment to moment.'"

From "The Running Conversation in Your Head/What a close study of "inner speech" reveals about why humans talk to themselves."

ADDED: If thought-speech really runs 10 times faster than spoken-speech, then 6 minutes of thinking on your own is like an hour of talking with someone else. Assuming the substance and quality of the word flow are exactly the same, it's just way more efficient to think.

There is an obvious up-side to talking with someone else: You're getting feedback and new input, and you're feeling the warmth and excitement of the presence of another human being. To think of the up-side is immediately to see the downside: The quality of what the other person has to say might not be so wonderful, and the relationship might not be so good. And if your mind is talking to you at 10 times the speed of what your interlocutor is saying, how exasperating! The other person will seem hopelessly slow, and you want to interrupt.

But this new statistic — I wonder if it's really true — could help you to become a good listener. Realize that the other person isn't really only 10% as smart as you. It just feels that way, because you're thinking and he's speaking. Tell yourself: I should be having 10 thoughts for every one this seemingly tedious person gets out, and if I don't, I'm the slow one.

This subject reminded me of the much-reported research that supposedly showed that highly intelligent persons are happier with less socializing and more time to themselves. The 10 to 1 ratio is for one individual: The conversation in your head goes 10 times as fast as your spoken word. But what's the ratio between the speed of your thoughts and the speed of the speech of that person you're stuck talking to? If you are a highly intelligent person talking to somebody average, maybe the ratio is 100 to 1. No wonder the HIP wants to stay home and read.

Ah, reading. That's another topic entirely. Just because your thought-speech is fast doesn't mean you're reading that fast. I would hypothesize that a HIP might read slowly because his own thought flow is overwhelming the process of eyeballing words on the page. What is the ratio of the speed of the words generated in your mind as you read? Perhaps some people produce 10 thought words for every word on the page they manage to absorb. Maybe HIPs have a 100 to 1 ratio. Takes him all day to read a blog post.