Very thorough book about recent findings differentiating brain signal processing and consciousness. It contains an extensive bibliography and an excellent index, though the information content could be improved slightly through more color images.

The unconscious brain still responds to external stimulus (primarily sounds) at one level, but these responses don't go anywhere. The author uses the interesting metaphor of Sherlock Holmes, gathering several clues before acting on the information. In the unconscious mind, Sherlock is absent, and the clues go unprocessed.

This book describes a process of masking information, similar to optical illusions, so the conscious mind does not see it. Another example is the famous gorilla that walks through the basketball scene - when the brain is focused on one thing, it misses another. This masking is then utilized, with MRI and other modern methods, to study just how information flows in the brain. When conscious, this leads to an information cascade that doesn't appear otherwise.

These techniques can be (and have been) used on patients assumed to be in a vegetative state, what earlier generations would have called brain-dead, and was successful in predicting recovery of some patients. To me, this was the most important part of the book - reaching a patient who could be "locked in" their own unresponsive body.

The author has participated in some preliminary work on modeling this brain function on a computer, and this wasn't explained as well as it could be. I hope that other people working on this with him present papers, articles or books on this topic soon - computing capacity continues to grow and what seemed impossible years ago is much easier today.

In summary, some great ideas are presented, occasional anecdotes get the message across, and the topic is fairly accessible. The language was a bit technical at times, and a few more illustrations would help with those less knowledgeable about the brain. A solid 4½ stars, and highly recommended.