What kind of brain is the Web giving us? That question will no doubt be the subject of a great deal of research in the years ahead. Already, though, there is much we know or can surmise—and the news is quite disturbing. Dozens of studies by psychologists, neurobiologists, and educators point to the same conclusion: When we go online, we enter an environment that promotes cursory reading, hurried and distracted thinking, and superficial learning. Even as the Internet grants us easy access to vast amounts of information, it is turning us into shallower thinkers, literally changing the structure of our brain.