It comes as no surprise that neuroplasticity has been linked to mental afflictions ranging from depression to obsessive-compulsive disorder to tinnitus. The more a sufferer concentrates on his symptoms, the deeper those symptoms are etched into his neural circuits. In the worst cases, the mind essentially trains itself to be sick.

Dozens of studies by psychologists, neurobiologists, educators, and Web designers point to the same conclusion: when we go online, we enter an environment that promotes cursory reading, hurried and distracted thinking, and superficial learning. It’s possible to think deeply while surfing the Net, just as it’s possible to think shallowly while reading a book, but that’s not the type of thinking the technology encourages and rewards.

The Net’s interactivity gives us powerful new tools for finding information, expressing ourselves, and conversing with others. It also turns us into lab rats constantly pressing levers to get tiny pellets of social or intellectual nourishment.

We usually make better decisions, his experiments reveal, if we shift our attention away from a difficult mental challenge for a time. But Dijksterhuis’s work also shows that our unconscious thought processes don’t engage with a problem until we’ve clearly and consciously defined the problem.3 If we don’t have a particular intellectual goal in mind, Dijksterhuis writes, “unconscious thought does not occur.”

was once assumed that long-term memory served merely as a big warehouse of facts, impressions, and events, that it “played little part in complex cognitive processes such as thinking and problem-solving.”14 But brain scientists have come to realize that long-term memory is actually the seat of understanding. It stores not just facts but complex concepts, or “schemas.” By organizing scattered bits of information into patterns of knowledge, schemas give depth and richness to our thinking. “Our intellectual prowess is derived largely from the schemas we have acquired over long periods of time,” says Sweller. “We are able to understand concepts in our areas of expertise because we have schemas associated with those concepts.”15

In worrying that writing would enfeeble memory, Socrates was, as the Italian novelist and scholar Umberto Eco says, expressing “an eternal fear: the fear that a new technological achievement could abolish or destroy something that we consider precious, fruitful, something that represents for us a value in itself, and a deeply spiritual one.”

The research also revealed the basic physiological difference between the two types of memory: “Short-term memory produces a change in the function of the synapse, strengthening or weakening preexisting connections; long-term memory requires anatomical changes.”

memory.”26 When our sleep suffers, studies show, so, too, does our memory.27

In contrast to working memory, with its constrained capacity, long-term memory expands and contracts with almost unlimited elasticity, thanks to the brain’s ability to grow and prune synaptic terminals and continually adjust the strength of synaptic connections. “Unlike a computer,” writes Nelson Cowan, an expert on memory who teaches at the University of Missouri, “the normal human brain never reaches a point at which experiences can no longer be committed to memory; the brain cannot be full.”31 Says Torkel Klingberg, “The amount of information that can be stored in long-term memory is virtually boundless.”

We don’t constrain our mental powers when we store new long-term memories. We strengthen them. With each expansion of our memory comes an enlargement of our intelligence. The Web provides a convenient and compelling supplement to personal memory, but when we start using the Web as a substitute for personal memory, bypassing the inner processes of consolidation, we risk emptying our minds of their riches.

WHAT DETERMINES WHAT we remember and what we forget? The key to memory consolidation is attentiveness. Storing explicit memories and, equally important, forming connections between them requires strong mental concentration, amplified by repetition or by intense intellectual or emotional engagement. The sharper the attention, the sharper the memory. “For a memory to persist,” writes Kandel, “the incoming information must be thoroughly and deeply processed. This is accomplished by attending to the information and associating it meaningfully and systematically with knowledge already well established in memory.”

A series of psychological studies over the past twenty years has revealed that after spending time in a quiet rural setting, close to nature, people exhibit greater attentiveness, stronger memory, and generally improved cognition. Their brains become both calmer and sharper.

The reason, according to attention restoration theory, or ART, is that when people aren’t being bombarded by external stimuli, their brains can, in effect, relax. They no longer have to tax their working memories by processing a stream of bottom-up distractions. The resulting state of contemplativeness strengthens their ability to control their mind.