The Shallows: What the Internet Is Doing to Our Brains

Chapter 1 begins with a description of the supercomputer HAL’s death scene in Stanley Kubrick’s 2001: A Space Odyssey. Carr compares how HAL could feel its mind changing to how Carr has noticed his own mind changing over the course of his lifetime: “Over the last few years I’ve had an uncomfortable sense that someone, or something, has been tinkering with my brain, remapping the neural circuitry” (5). Carr notes that his memory and focus have both been affected by his increasing use of the Internet. He isn’t the only person to notice these changes; Carr quotes bloggers, doctoral students, university professors, and communications professionals who all claim that their thinking has become more scattered, their reading shallower, and their need for quickly changing stimuli more powerful the more they rely on the Internet. 

Carr provides a brief timeline of the Internet’s rise using his own life as an example. Born in 1959, Carr says, “My life, like the lives of most Baby Boomers and Generation Xers, has unfolded like a two-act play. It opened with Analogue Youth and then, after a quick but thorough shuffling of the props, it entered Digital Adulthood” (10-11). Carr went to college in 1977 at Dartmouth, where he sparingly used the university’s early form of computing, and he bought his first personal computer, the Mac Plus, in 1986. From 1986 to 1995, Carr purchased upgraded Apple products as they launched, and his writing life moved from printed pages to word processing. When the Internet, a “network of networks,” appeared, Carr adopted its use, eventually becoming a “social networker and content generator” by 2005 (14-15). Around 2007, Carr noticed, “just as Microsoft Word had turned [him] into a flesh-and-blood word processor, the Internet, [he] sensed, was turning [him] into something like a high-speed data-processing machine, a human HAL” (16).

Chapter 2 explores how neuroscience shifted from assuming the adult brain was fixed in its thinking patterns and physical structure to discovering that the adult brain is constantly adjusting to external stimuli: The brain is plastic, and it can change. Despite advances in neuroscience through the 20th century, like Sigmund Freud’s discovery of the neuron, the synapse, and neurotransmitters, “most biologist and neurologists continued to believe, as they had for hundreds of years, that the structure of the adult brain never changed” (20). Carr connects this scientific assumption to the Industrial and Enlightenment Age metaphor of the brain as a mechanical device, a machine with specific parts that cannot change. In 1968, neuroscientist Michael Merzenich observed the nervous system of primates reorganizing itself after nerve damage, and subsequent experiments proved that the human brain is equally plastic: “virtually all of our neural circuits—whether they’re involved in feeling, seeing, hearing, moving, thinking, learning, perceiving, or remembering—are subject to change” (26). Carr explains Eric Kandel’s 1970s experiment on the sea slug, which showed that lived experiences can train synapses to increase or decrease their sensitivity: The brain physically changes itself quickly in response to repeated stimulus. These experiments, among others, prove that the human brain is designed to reorganize itself throughout its lifetime based on shifts in behavior and circumstance.

The brain not only changes itself based on physical stimuli, but it can also change itself based on repeated thought patterns. Carr describes two experiments, one from the 1990s with London cab drivers and one by Pascual-Leone with piano players, where participants showed the same kind of neural development after repeated mental activity as they did after repeated physical activity. Carr summarizes these findings by saying, “We become, neurobiologically, what we think” (33). The process by which areas of the brain are changed or strengthened in response to repeated use also causes areas of the brain to change in response to disuse. Research psychiatrist Norman Doidge writes, “[T]he paradox of neuroplasticity […] is that, for all the mental flexibility it grants us, it can end up locking us into ‘rigid behaviors’” (34). According to Pascual-Leone, the same plasticity that allows the brain to learn new skills is what makes the brain susceptible to addiction, depression, and obsessive-compulsive disorder. Carr describes these neural pathways formed by repeated use as “the vital paths.” The vital paths are neurological pathways in the brain that are affected by repeated activity, and though they can change, they can also become rigid over time.

Carr includes four interstitial sections titled “digressions” at various points throughout the book. The first digression discusses different philosophical understandings of the brain, including Aristotle’s description of the brain as an organ that cools the blood and Descartes’ metaphor of the brain as a kind of hydraulic system that turns blood into spirit. The brain is different from other vital organs because people cannot feel their brains working in the way that they can feel their blood pumping or their lungs inflating. Carr explains that “the brain’s strangely remote quality […] influences our perceptions in subtle ways […] we have a sense that our brain exists in a state of splendid isolation […] impervious to the vagaries of our day-to-day lives” (37-38). Carr confesses his initial resistance to the idea that his brain could be so heavily influenced by a tool—the Internet—but asserts that neuroscience proves the brain is always changing with the use of new tools.