RETHINKING CONSCIOUSNESS

Graziano (Psychology and Neuroscience/Princeton Univ.; The Spaces Between Us: A Story of Neuroscience, Evolution, and Human Nature, 2018, etc.) continues to probe the mysteries of consciousness.

Explaining how our physical brain generates consciousness is officially labeled the “hard problem,” and readers of this admirable attempt to solve it will not disagree. A thermostat registers temperature; a computer can evaluate information and make decisions. The assembly of neurons in the brain does the same, and neuroscientists are working out the mechanism. However, brains not only do stuff; their possessors also know that they are doing stuff. They are having mental experiences. Brain cells detect color, but how do we experience redness? “A modern computer can process a visual image,” writes the author, “but engineers have not yet solved how to make the computer conscious of that information.” Although their numbers are diminishing, some scholars insist that something as amorphous as consciousness can never be explained scientifically. Graziano points out that plenty of theories exist, including one he favors, which “can apply equally to biological brains and artificial machines.” He opts for what he calls the attention schema, which emphasizes that the brain is an information-processing machine that generates a conscious experience but has no way to relate this to reality. As a result, we construct a rich internal model that we consult to assure us that our perceptions are correct. We also use this model to predict the behavior of others—i.e., social cognition. It works pretty well but not perfectly. Graziano also provides an excellent history of brain evolution beginning with the first nerve cell 700 million years ago. Since consciousness is complex—but not confined to humans; other animals have it—understanding it requires a knowledge of brain function. The author delivers a lucid account, but once he focuses on his specialty, few readers will doubt that the phrase “hard problem” is no exaggeration.

A fine popular introduction to the brain and an earnest if difficult attempt to explain how it generates consciousness.