This is hidden brain.
I'm Shankar Vedantam.
One of the most enduring puzzles of the human brain is that when we look inward, we see what feels like a complete picture.
We perceive our feelings, remember memories, and make plans for the future.
Over the last several decades, however, psychologists have shown that significant portions of our minds are, in fact, hidden from us.
They operate outside or below the spotlight of conscious awareness.
Here's a simple way to demonstrate this.
I'll ask you a question, and you give me an answer.
Here's the question.
Fill in the last word in this sentence.
The 4 July is celebrated as Independence day in the United States of blank.
Okay, you think that was too easy?
It's the United States of America, of course.
But take a moment and reflect on what just happened inside your brain.
You heard my question, which is to say, the sound waves carrying my voice entered your ear.
The 4 July were converted into electrical signals and sent to your brain.
Neural networks transform these signals into words, into a sentence, decoded what it meant, and figured out the meaning of the question.
Systems in your brain that produce reasoning and memory retrieved the answer to the question.
This answer was then routed to centers in the brain that produced language.
Other brain systems shaped how your muscles pushed air through your lungs and pursed your lips, and you came up with America.