ON FEBRUARY 14, 1946, a breathless bustle filled the halls of the Moore School of Electrical Engineering in Philadelphia. On this day, the school’s secret jewel was going to be revealed to the world: the ENIAC. Inside a locked room at Moore hummed the Electronic Numerical Integrator and Computer, the first machine of its kind capable of performing calculations at lightning speed. Weighing thirty tons, the massive ENIAC used around eighteen thousand vacuum tubes, employed about six thousand switches, and encompassed upwards of half a million soldered joints; it had taken more than 200,000 man-hours to build. 

 

Commercial brain-training regimens like Cogmed, Lumosity, and BrainHQ have attracted many who desire to improve their memory and increase their focus; Lumosity alone claims 100 million registered users in 195 countries.

 

Visitors to the exhibit were instructed to place a finger on a sensor that detected their pulse; the readout of the sensor was visible only to Ainley. “Please tell me when your heart beats,” she would say to each patron who stepped forward. An elderly couple who stopped by the booth had very different reactions to Ainley’s request. “How on earth would I know what my heart is doing?” the woman asked incredulously. Her husband turned and stared at her, equally dumbfounded. “But of course you know,” he exclaimed. “Don’t be so stupid, everyone knows what their heartbeat is!” “He had always been able to hear his heart, and she had never been able to hear hers,” Ainley observed in an interview, smiling at the memory. “They had been married for decades, but they had never talked of or even recognized this difference between them.”

 

Rooted in the Buddhist traditions of Myanmar, Thailand, and Sri Lanka, the body scan was introduced to Western audiences by mindfulness pioneer Jon Kabat-Zinn, now a professor emeritus at the University of Massachusetts Medical School. “People find the body scan beneficial because it reconnects their conscious mind to the feeling states of their body,” says Kabat-Zinn. “By practicing regularly, people usually feel more in touch with sensations in parts of their body they had never felt or thought much about before.”

 

The body scan trains us to observe such sensations with interest and equanimity. But tuning in to these feelings is only a first step. The next step is to name them. Attaching a label to our interoceptive sensations allows us to begin to regulate them; without such attentive self-regulation, we may find our feelings overwhelming, or we may misinterpret their source. Research shows that the simple act of giving a name to what we’re feeling has a profound effect on the nervous system, immediately dialing down the body’s stress response.

 

Half of the participants were then asked to engage in what the researchers call “affect labeling,” filling in responses to the prompt “I feel _________,” while the other half were asked to complete a neutral shape-matching task. The affect-labeling group showed steep declines in heart rate and skin conductance compared to the control group, whose levels of physiological arousal remained high.

 

THAT’S EMPHATICALLY not the case in the classroom helmed by Maureen Zink, a fourth-grade teacher at Vallecito Elementary School in San Rafael, California. Her students don’t sit still at their desks; in fact, most of them are not sitting at all. In 2013, the entire school replaced traditional desks and chairs with standing desks, and the school’s “activity-permissive” ethos allows pupils to stand upright, perch on stools, sit on the floor, and otherwise move around as they wish. Though some were hesitant about the change, Zink and the other teachers at Vallecito now say it’s been a resounding success; students are more alert, more attentive, and more engaged. “I taught at sitting desks for 30 years,” says Zink, “and I’ll never go back.” Tracy Smith, the principal at Vallecito during the switch to standing desks, agrees that students are “more focused, confident, and productive” when given license to move. 

 

Ever the scientist, Kahneman has subjected the experience to close analysis. “I usually keep track of my time and have learned a fair amount about effort from doing so,” he writes. “I have found a speed, about 17 minutes for a mile, which I experience as a stroll. I certainly exert physical effort and burn more calories at that speed than if I sat in a recliner, but I experience no strain, no conflict, and no need to push myself. I am also able to think and work while walking at that rate. Indeed, I suspect that the mild physical arousal of the walk may spill over into greater mental alertness.”

 

At the highest speed I can sustain on the hills, about 14 minutes for a mile, I do not even try to think of anything else.”

 

Achieving transient hypofrontality generally requires exercising at one’s “ventilatory threshold”—the point at which breathing becomes labored, corresponding to about 80 percent of the exerciser’s maximum heart rate—for forty minutes or more.

 

Concluded Helga and Tony Noice in one of their academic articles, “One might paraphrase Descartes and say, ‘I move, therefore I remember.’ ”

 

Remember Friedrich Nietzsche, from earlier in our journey. “Only thoughts which come from walking have any value,” he maintained. Søren Kierkegaard felt similarly. “I have walked myself into my best thoughts,” remarked the Danish philosopher. Walking is “gymnastics for the mind,” observed the American writer Ralph Waldo Emerson. “I am unable to reflect when I am not walking; the moment I stop, I think no more, and as soon as I am again in motion, my head resumes its workings,” averred the Swiss-born philosopher Jean-Jacques Rousseau. The French philosopher and essayist Michel de Montaigne lamented that his thoughts often came to him when he was on the move, at moments when “I have nothing to jot them down on”; this was wont to happen “especially on my horse, the seat of my widest musings.”

 

High-income parents gesture more than low-income parents, research finds. And it’s not just the quantity of gesture that differs but also the quality: more affluent parents provide a greater variety of types of gesture, representing more categories of meaning—physical objects, abstract concepts, social signals. Parents and children from poorer backgrounds, meanwhile, tend to use a narrower range of gestures when they interact with each other. Following the example set by their parents, high-income kids gesture more than their low-income counterparts. In one study, fourteen-month-old children from high-income, well-educated families used gesture to convey an average of twenty-four different meanings during a ninety-minute observation session, while children from lower-income families conveyed only thirteen meanings. Four years later, when it was time to start school, children from the richer families scored an average of 117 on a measure of vocabulary comprehension, compared to 93 for children from the poorer families. 

 

The good news: research shows that offering simple instructions to parents leads them to gesture more often; in turn, their children also gesture more.

 

Landowners in the bone-dry southwest United States irrigate their properties to evoke the lush, grassy savanna. Gardeners in Japan prune their trees so that the boughs resemble the spreading branches of the trees of East Africa. Such choices reflect the brain’s very particular evolved history—the “ghosts of environments past,” in the phrase of biologist Gordon Orians. What we imagine to be aesthetic preferences are really survival instincts honed over millennia, instincts that helped us find promising places to forage and to rest. When, today, we turn to nature when we’re stressed or burned out—when we take a walk through the woods or gaze out at the ocean’s rolling waves—we are engaging in what one researcher calls “environmental self-regulation,” a process of psychological renewal that our brains cannot accomplish on their own.

 

Biophilic design is an emerging discipline, but a handful of studies have begun to suggest that working and learning in buildings inspired by nature can grant some of the same benefits for cognition as actually being outdoors.

 

“Good fences make good neighbors,” wrote poet Robert Frost; likewise, good walls make good collaborators.

 

One recent study, conducted in a British government agency that switched from enclosed offices to an open-plan workspace, found that the heightened imperative to engage in self-presentation in such settings fell most heavily on women, for whom appearance is considered especially important.) When people are relieved of the cognitive load imposed by their environment, they immediately become more creative, neuroscientist Moshe Bar has found.

 

“When thought overwhelms the mind, the mind uses the world,” psychologist Barbara Tversky has observed.

 

Once we recognize this possibility, we can deliberately shape the material worlds in which we learn and work to facilitate mental extension—to enhance “the cognitive congeniality of a space,” in the words of David Kirsh, a professor at the University of California, San Diego.

 

Even so ordinary a ritual as sharing a meal can make a difference in how well a group thinks together. Lakshmi Balachandra, an assistant professor of entrepreneurship at Babson College in Massachusetts, asked 132 MBA students to role-play executives negotiating a complex joint venture agreement between two companies. In the simulation she arranged, the greatest possible profits would be created by parties who were able to discern the other side’s preferences and then work collectively to maximize profits for the venture as a whole, rather than merely considering their own company’s interests. Balachandra found that participants who dined together while negotiating—at a restaurant, or over food brought into a conference room—generated 12 percent higher profits, on average, than those who bargained while not eating.

 

For example: scientists at Germany’s Max Planck Institute and elsewhere are experimenting with automatic “rapport detection” within groups. Sensors embedded in a conference room or in video-conferencing equipment unobtrusively monitor group members’ nonverbal behavior (their facial expressions, hand motions, gaze direction, and so on); these data are analyzed in real time to yield a measure of how well a group is cooperating. When rapport falls below a critical level, nudges can be applied to move the group toward greater cohesion: the system might alert the group’s leader that a shared coffee break is in order, or it might suggest to him, via a pop-up message, that he engage in more mirroring of his co-workers. Inside wired-up “smart meeting rooms,” it may even elect to raise the temperature by a few degrees, or introduce some soothing white noise. 

 

Steven Rogelberg, a professor of management at the University of North Carolina at Charlotte, notes that group members “often hold back in meetings, waiting to hear what others say and what their boss might say out of fear of being perceived as difficult, out of touch, or off the mark.” Asking attendees to write out their contributions instead of speaking them, he says, “can be a solution to this problem, allowing space for unique knowledge and novel ideas to emerge.” Participants jot down their thoughts on index cards, which the group’s leader then reads aloud. Or they write them on sheets of paper posted around the room, after which participants circulate again—this time marking down comments on their colleagues’ ideas, which the group as a whole then discusses.

 

Upon assuming this role, Sunstein learned a valuable lesson in group leadership: if he began a meeting by stating his own views, he discovered, the ensuing discussion was far less expansive and open than if he started out by saying, “What do you all think? This is a tough one.” As soon as a leader makes his preferences known, says Sunstein, many who work for him will choose to engage in “self-silencing” rather than rock the boat with a dissenting view. And, he notes, “some people are more likely to silence themselves than others”; these may include women and members of minority groups, as well as individuals with less status, less experience, or less education. Yet it’s just this range of voices that must be heard if the group mind is to exert its unique power. One solution, says Sunstein, is for leaders to silence themselves; the manager or administrator who adopts an “inquisitive and self-silencing” stance, he maintains, has the best chance of hearing more than his own views reflected back to him.

 

Philosopher Andy Clark, observing the progressive delegation of our mental operations to our devices, has noted that “the mind is just less and less in the head” these days. More than that, the mind must be less and less in the head, and more and more emblazoned on the world, if we are to extend our minds with the minds of others.

 

Rather, researchers recommend that we implement a specific sequence of actions in response to our teammates’ contributions: we should acknowledge, repeat, rephrase, and elaborate on what other group members say. Studies show that engaging in this kind of communication elicits more complete and comprehensive information. It re-exposes the entire group to the information that was shared initially, improving group members’ understanding of and memory for that information. And it increases the accuracy of the information that is shared, a process that psychologists call “error pruning.” Although it may seem cumbersome or redundant, research suggests that this kind of enhanced communication is part of what makes expert teamwork so effective. A study of airplane pilots, for example, found that experienced aviators regularly repeated, restated, and elaborated on what their fellow pilots said, while novice pilots failed to do so—and as a result, the less experienced pilots formed sparser and less accurate memories of their time in the air.

 

In addition to being shared, it’s beneficial for group artifacts to be large and complex. The Olsons have found that people often gesture at large artifacts, enhancing their own thinking and that of the people who observe them; meanwhile, a complex artifact (as opposed to a simple or schematic one) allows more of the group’s thinking to be explicitly represented for all to see, rather than remaining concealed inside individuals’ heads. Finally, shared artifacts are most effective when they are persistent—preserved, retained, and kept continuously visible—but also revisable, able to be changed as new information or insight emerges. Describing another team at work, the Olsons noted that this group’s artifacts “were often put up in the order in which they were produced. People knew where to look for something because they knew when it was produced, and they could tell something about another person’s attention by seeing where that person was looking.”

 

One of the great advantages of the group mind is its capacity to bring together many and varied areas of proficiency, ultimately encompassing far more expertise than could ever be held in a single mind. We couldn’t know all that our fellow group members know, nor should we want to; our mental bandwidth would quickly become overloaded. We do, however, need to know that they know it, in order to call upon it when it’s needed. The process by which we leverage an awareness of the knowledge other people possess is called “transactive memory.”

 

Group members should be explicitly informed about their colleagues’ distinctive talents or spheres of specialization, and clear protocols should be established for directing questions and tasks to the appropriate individual. Research shows that groups perform best when each member is clearly in charge of maintaining a particular body of expertise—when each topic has its designated “knowledge champion,” as it were. Studies further suggest that it can be useful to appoint a meta-knowledge champion: an individual who is responsible for keeping track of what others in the group know and making sure that group members’ mental “directory” of who knows what stays up to date.

 

This is how it worked: Students were divided into groups of five or six. When a class began a new unit—say, on the life of Eleanor Roosevelt—each student in the group was assigned one section of the material: Roosevelt’s childhood and young adulthood, or her role as first lady, or her work on behalf of causes such as civil rights and world peace. The students’ task was to master their own section, then rejoin the group and report to the others on what they had learned. “Each student has possession of a unique and vital part of the information, which, like the pieces of a jigsaw puzzle, must be put together before anyone can learn the whole picture,” Aronson explained. By arranging instruction in this manner, he was effectively creating a transactive memory system on the spot, turning each student into an expert on a particular facet of the subject under study. “In this situation,” Aronson added, “the only way a child can be a good learner is to begin to be a good listener and interviewer”; the jigsaw structure “demands that the students utilize one another as resources.”

 

The first set of principles lays out some habits of mind we would do well to adopt, starting with this one: whenever possible, we should offload information, externalize it, move it out of our heads and into the world.

 

Offloading need not require written language, either. At times, offloading may be embodied: when we gesture, for example, we permit our hands to “hold” some of the thoughts we would otherwise have to maintain in our head. Likewise, when we use our hands to move objects around, we offload the task of visualizing new configurations onto the world itself, where those configurations take tangible shape before our eyes. (Picture an interior designer manipulating a model as she tries out new groupings of furniture, for example, or a Scrabble player rearranging the tiles on his tray to form new words.)

 

Onward to the second principle: whenever possible, we should endeavor to transform information into an artifact, to make data into something real—and then proceed to interact with it, labeling it, mapping it, feeling it, tweaking it, showing it to others. Humans evolved to handle the concrete, not to contemplate the abstract. We extend our intelligence when we give our minds something to grab onto: when we experience a concept from physics as a bicycle wheel spinning in our hands, for example, or when we turn a foreign language vocabulary word into a gesture we can see and sense and demonstrate to others.

 

In a related vein, the third principle: whenever possible, we should seek to productively alter our own state when engaging in mental labor.

 

Effective mental extension, then, requires us to think carefully about inducing in ourselves the state that is best suited for the task at hand. We might engage in a bout of brisk exercise before sitting down to learn something new, for example; we might seek out an opportunity to engage in group synchrony and shared physical arousal (spicy food, anyone?) when we’re expected to work together as a team. We might get up from our desk and get our hands and bodies moving when we’re seeking to understand a spatial concept; we might plan a three-day trip into the wilderness when we’re in need of a creative boost. Deliberately altering our own state could entail taking a walk in a nearby park when our frazzled attention requires restoration, or seeking out a sparring partner with whom to argue when we want to make sure our ideas are sound. Instead of heedlessly driving the brain like a machine, we’ll think more intelligently when we treat it as the context-sensitive organ it is. 

 

The second set of principles offers a higher-level view of how mental extension works, in accordance with an understanding of what the brain evolved to do. The brain is well adapted to sensing and moving the body, to navigating through physical space, and to interacting with other members of our species. On top of this basic suite of human competencies, civilization has built a vast edifice of abstraction, engaging our brains in acts of symbolic processing and conceptual cognition that don’t come as naturally. These abstractions have, of course, allowed us to expand our powers exponentially—but now, paradoxically, further progress may depend on running this process in reverse. In order to succeed at the increasingly complex thinking modern life demands, we will find ourselves needing to translate abstractions back into the corporeal, spatial, and social forms from which they sprang—forms with which the brain is still most at ease. 

 

We can begin to understand what this means by taking up the fourth principle: whenever possible, we should take measures to re-embody the information we think about. The pursuit of knowledge has frequently sought to disengage thinking from the body, to elevate ideas to a cerebral sphere separate from our grubby animal anatomy. Research on the extended mind counsels the opposite approach: we should be seeking to draw the body back into the thinking process. That may take the form of allowing our choices to be influenced by our interoceptive signals—a source of guidance we’ve often ignored in our focus on data-driven decisions. It might take the form of enacting, with bodily movements, the academic concepts that have become abstracted, detached from their origin in the physical world. Or it might take the form of attending to our own and others’ gestures, tuning back in to what was humanity’s first language, present long before speech. As we’ve seen from research on embodied cognition, at a deep level the... 

 

The fifth principle emphasizes another human strength: whenever possible, we should take measures to re-spatialize the information we think about. We inherited “a mind on the hoof,” as Andy Clark puts it: a brain that was built to pick a path through a landscape and to find the way back home. Neuroscientific research indicates that our brains process and store information—even, or especially, abstract information—in the form of mental maps. We can work in concert with the brain’s natural spatial orientation by placing the information we encounter into expressly spatial formats: creating memory palaces, for example, or designing concept maps. In the realm of education research, experts now speak of “spatializing the curriculum”—that is, simultaneously drawing on and strengthe...

 

The sixth principle rounds out the roster of our innate aptitudes: whenever possible, we should take measures to re-socialize the information we think about. We learned earlier in this book that the continual patter we carry on in our heads is in fact a kind of internalized conversation. Likewise, many of the written forms we encounter at school and at work—from exams and evaluations, to profiles and case studies, to essays and proposals—are really social exchanges (questions, stories, arguments) put on paper and addressed to some imagined listener or interlocutor. As we’ve seen, there are significant advantages to turning such interactions at a remove back into actual social encounters.

 

such as the one encapsulated in the seventh principle: whenever possible, we should manage our thinking by generating cognitive loops.

 

compute for a while, print out the results, inspect what they have produced, add some marks in the margin, circulate copies among colleagues, and then start the process again. That’s not how computers work—but it is how we work; we are “intrinsically loopy creatures,” as Clark likes to say. Something about our biological intelligence benefits from being rotated in and out of internal and external modes of cognition, from being passed among brain, body, and world. This means we should resist the urge to shunt our thinking along the linear path appropriate to a computer—input, output, done—and instead allow it to take a more winding route.

 

What we shouldn’t do is keep our thoughts inside our heads, inert, unchanged by encounters with the world beyond the skull.

 

Hence, the eighth principle: whenever possible, we should manage our thinking by creating cognitively congenial situations. We often regard the brain as an organ of awesome and almost unfathomable power. But we’re also apt to treat it with high-handed imperiousness, expecting it to do our bidding as if it were a docile servant. Pay attention to this, we tell it; remember that; buckle down now and get the job done. Alas, we often find that the brain is an unreliable and even impertinent attendant: fickle in its focus, porous in its memory, and inconstant in its efforts. The problem lies in our attempt to command it. We’ll elicit improved performance from the brain when we approach it with the aim not of issuing orders but of creating situations that draw out the desired result.

 

Accordingly, the ninth principle: whenever possible, we should manage our thinking by embedding extensions in our everyday environments.