Explorations of Inner Space: Cognitive Neuroscience at the Brink of the 21st Century

The fascinating and unexpected syndromes associated with focal insult to the brain have led to important advances in our understanding of human cognition. Cognitive neuroscience builds on such observations to investigate how we can read this sentence and to solve other mental problems that previously seemed so impenetrable. Several engaging books have been published recently by world-class experts in the field, and this review samples some of the thinking presented in these superb volumes.

Consider the complexity of the mental processes involved in reading. Our visual apparatus interprets a random set of squiggles as symbols representing the letters of a word. The arbitrary pairing of each word with its associated concept is decoded in our mental dictionary, and our grammatical processor assembles the words of the sentence so that we can establish who is doing what to whom. Because this process evolves over time, our working memory must retain critical aspects of these representations until the processing of the sentence is complete. Ultimately, the overall meaning of the sentence emerges.

One central theme of Steven Pinker's 1997 book, How the Mind Works [1], is the computational theory of cognition, according to which a massive number of simple processing devices work in concert to accomplish complex tasks. This view is outlined lucidly for several cognitive domains, including visual perception, spatial relations, and logical reasoning. Consider one example related to reading-the task of interpreting the visual squiggles that we call a letter. Remarkable flexibility is required to recognize all of the different fonts in all of the possible sizes in which letters can be written. Commuters appreciate that letters can be recognized upside-down, sideways, and in a mirror (with a little practice), despite the bouncing that newspaper readers endure in the subway. Letters are routinely written in radically different shapes (for …