My essay for the New York Times about the extended mind

A good introduction to the subject.

Years ago, when I was in college, I visited the dorm room of a fellow student I was dating. On the wall above his desk he had posted a handwritten sign. “Just do it,” it read, in blocky letters. Nike’s slogan was intended to capture an attitude toward athletic endeavors, but this undergrad was applying it to mental exertions. I pictured him sitting at his desk, working hour after hour on his German verb conjugations or econ problem sets. At some point he would become restless, lose focus — then look up at his sign, set his jaw and turn back to his studies, determined to crush them like a 100-meter dash.

My classmate back then was doing exactly what our culture commands when we are faced with challenging cognitive tasks: Buckle down, apply more effort, work the brain ever harder. This, we’re told, is how we get good at thinking. The message comes at us from multiple directions. Psychology promotes a tireless kind of grit as the quality essential to optimal performance; the growth mind-set advises us to imagine the brain as a muscle and to believe that exercising it vigorously will make it stronger. Popular science accounts of the brain extol its power and plasticity, calling it astonishing, extraordinary, unfathomably complex. This impressive organ, we’re led to understand, can more than meet any demands we might make of it.

In the 25 years since I graduated from college, such demands have relentlessly ratcheted up. The quantity and complexity of the mental work expected of successful students and professionals have mounted; we’ve responded by pushing ever harder on that lump of gray matter in our heads. This tendency became more pronounced during the Covid-19 pandemic, when many of us had to take on new duties or adjust to new procedures. Without even a commute or a coffee-station chat to provide a break in our cognitive labors, we’ve been forcing our brains to toil continuously from morning till night.

The result has not been a gratifying bulking up of our neural “muscle.” On the contrary, all the mental effort we’ve mustered over the past year has left many of us feeling depleted and distracted, unequal to the tasks that never stop arriving in our inboxes. When the work we’re putting in doesn’t produce the advertised rewards, we’re inclined to find fault with ourselves. Maybe we’re insufficiently gritty; maybe, we think, we’re just not smart enough. But this interpretation is incorrect. What we’re coming up against are universal limits, constraints on the biological brain that are shared by every human on the planet. Despite the hype, our mental endowment is not boundlessly powerful or endlessly plastic. The brain has firm limits — on its ability to remember, its capacity to pay attention, its facility with abstract and nonintuitive concepts — and the culture we have created for ourselves now regularly exceeds these limits.

The escalating mental demands of the past quarter-century represent the latest stage of a trend that has been picking up speed for more than 100 years. Starting in the early decades of the 20th century, school, work and even the routines of daily life became more cognitively complex: less grounded in the concrete and more bound up in the theoretical and abstract. For a time, humanity was able to keep up with this development, resourcefully finding ways to use the brain better. As their everyday environments grew more intellectually demanding, people responded by upping their cognitive game. Continual engagement with the mental rigors of modern life coincided in many parts of the world with improving nutrition, rising living conditions and reduced exposure to pathogens. These factors produced a century-long climb in average I.Q. scores — a phenomenon known as the Flynn effect, after James Flynn, the political philosopher who identified it.

But this upward trajectory is now leveling off. In recent years, I.Q. scores have stopped rising or have even begun to drop in countries like Finland, Norway, Denmark, Germany, France and Britain. (The reverse Flynn effect has not yet been detected in the United States.) Some researchers suggest that we have pushed our mental equipment as far as it can go. It may be that “our brains are already working at near-optimal capacity,” write the neuroscientist Peter Reiner and his student Nicholas Fitz in the journal Nature. Efforts to wrest more intelligence from this organ, they add, “bump up against the hard limits of neurobiology.” This collision point — where the urgent imperatives of contemporary life confront the stubbornly intractable limits of the brain — is the place where we live at the moment, and rather unhappily. Our determination to drive the brain ever harder is the source of the agitation we feel as we attempt the impossible each day.

Fortunately, there is an alternative. It entails inducing the brain to play a different role: less workhorse, more orchestra conductor. Instead of doing so much in our heads, we can seek out ways to shift mental work onto the world around us and to supplement our limited neural resources with extraneural ones. These platforms for offloading, these resources for supplementation, are readily available and close at hand.

They fall into four categories, the first and most obvious being our tools. Technology is designed to fulfill just this function — who remembers telephone numbers anymore, now that our smartphones can supply them? — and we’re accustomed to using our devices to both unburden the mind and augment its capacity.

But there are other resources, perhaps even more powerful, that we often overlook. For example, our bodies. The burgeoning field of embodied cognition has demonstrated that the body — its sensations, gestures and movements — plays an integral role in the thought processes that we usually locate above the neck. The body is especially adept at alerting us to patterns of events and experience, patterns that are too complex to be held in the conscious mind. When a scenario we encountered before crops up again, the body gives us a nudge: communicating with a shiver or a sigh, a quickening of the breath or a tensing of the muscles. Those who are attuned to such cues can use them to make more-informed decisions. A study led by a team of economists and neuroscientists in Britain, for instance, reported that financial traders who were better at detecting their heartbeats — a standard test of what is known as interoception, or the ability to perceive internal signals — made more profitable investments and lasted longer in that notoriously volatile profession.

The body is also uniquely capable of grounding abstract concepts in the concrete terms that the brain understands best. Abstract concepts are the order of the day in physics class; conventional modes of instruction, like lectures and textbooks, often fail to convey them effectively. Some studies in the field of physics education found that students’ understanding of the subject is less accurate after an introductory college physics course. What makes a difference is offering students a bodily experience of the topic they’re learning about. They might encounter torque, for example, by holding an axle on which two bicycle wheels have been mounted. When the wheels are spun and the axle is tilted from horizontal to vertical, the student handling it feels the resistive force that causes objects to rotate. Such exposures produce a deeper level of comprehension, psychological research has found, leading to higher test scores, especially on more challenging theoretical questions.

Another extraneural resource available for our use is physical space. Moving mental contents out of our heads and onto the space of a sketch pad or whiteboard allows us to inspect it with our senses, a cognitive bonus that the psychologist Daniel Reisberg calls “the detachment gain.” That gain was evident in a study published in 2016, in which experimenters asked seventh- and eighth-grade students to illustrate with drawings the operation of a mechanical system (a bicycle pump) and a chemical system (the bonding of atoms to form molecules). Without any further instruction, these students sketched their way to a more accurate understanding of the systems they drew. Turning a mental representation into shapes and lines on a page helped them to elucidate more fully what they already knew while revealing with ruthless rigor what they did not yet comprehend.

Three-dimensional space offers additional opportunities for offloading mental work and enhancing the brain’s powers. When we turn a problem to be solved into a physical object that we can interact with, we activate the robust spatial abilities that allow us to navigate through real-world landscapes. This suite of human strengths, honed over eons of evolution, is wasted when we sit still and think. A series of studies conducted by Frédéric Vallée-Tourangeau, a professor of psychology at Kingston University in Britain; Gaëlle Vallée-Tourangeau, a professor of behavioral science at Kingston; and their colleagues, has explored the benefits of such interactivity. In these studies, experimenters pose a problem; one group of problem solvers is permitted to interact physically with the properties of the problem, while a second group must only think through the problem. Interactivity “inevitably benefits performance,” they report.

This holds true for a wide variety of problem types — including basic arithmetic, complex reasoning, planning and challenges that require creative insight. People who are permitted to manipulate concrete tokens representing elements of the problem to be solved bear less of a cognitive load and enjoy increased working memory. They learn more and are better able to transfer their learning to new situations. They are less likely to engage in symbol pushing, or moving numbers and words around in the absence of understanding. They are more motivated and engaged and experience less anxiety. They even arrive at correct answers more quickly. (As the title of a research paper that the Vallée-Tourangeaus wrote with Lisa G. Guthrie puts it, “Moves in the World Are Faster Than Moves in the Head.”)

One last resource for augmenting our minds can be found in other people’s minds. We are fundamentally social creatures, oriented toward thinking with others. Problems arise when we do our thinking alone — for example, the well-documented phenomenon of confirmation bias, which leads us to preferentially attend to information that supports the beliefs we already hold. According to the argumentative theory of reasoning, advanced by the cognitive scientists Hugo Mercier and Dan Sperber, this bias is accentuated when we reason in solitude. Humans’ evolved faculty for reasoning is not aimed at arriving at objective truth, Mercier and Sperber point out; it is aimed at defending our arguments and scrutinizing others’. It makes sense, they write, “for a cognitive mechanism aimed at justifying oneself and convincing others to be biased and lazy. The failures of the solitary reasoner follow from the use of reason in an ‘abnormal’ context’” — that is, a nonsocial one. Vigorous debates, engaged with an open mind, are the solution. “When people who disagree but have a common interest in finding the truth or the solution to a problem exchange arguments with each other, the best idea tends to win,” they write, citing evidence from studies of students, forecasters and jury members.

The minds of other people can also supplement our limited individual memory. Daniel Wegner, a psychologist at Harvard, named this collective remembering “transactive memory.” As he explained it, “Nobody remembers everything. Instead, each of us in a couple or group remembers some things personally — and then can remember much more by knowing who else might know what we don’t.” A transactive memory system can effectively multiply the amount of information to which an individual has access. Organizational research has found that groups that build a strong transactive memory structure — in which all members of the team have a clear and accurate sense of what their teammates know — perform better than groups for which that structure is less defined. Linda Argote, a professor of organizational behavior and theory at Carnegie Mellon University, reported last year that results from an observational study showed that when a trauma resuscitation team developed a robust shared memory system and used it to direct tasks to the team members most qualified to take them on, their patients had shorter hospital stays.

All four of these extraneural resources — technology, the body, physical space, social interaction — can be understood as mental extensions that allow the brain to accomplish far more than it could on its own. This is the theory of the extended mind, introduced more than two decades ago by the philosophers Andy Clark and David Chalmers. A 1998 article of theirs published in the journal Analysis began by posing a question that would seem to have an obvious answer: “Where does the mind stop and the rest of the world begin?” They went on to offer an unconventional response. The mind does not stop at the usual “boundaries of skin and skull,” they maintained. Rather, the mind extends into the world and augments the capacities of the biological brain with outside-the-brain resources.

Much of the initial reaction to their thesis focused on disputes over whether the stuff of the world could really constitute an element of the thought process. For a culture so neurocentric — so brain-bound, as Mr. Clark later called it — this was an insupportable notion, a bridge too far. But their claim acquired more plausibility as daily life in the digital age provided a continuous proof of concept, with people extending their minds with their devices. Initially derided as wacky, the theory of the extended mind eventually came to seem rather prescient. Ned Block, a professor of philosophy at New York University, said that Mr. Clark and Mr. Chalmers’s thesis was false when it was written but subsequently became true.

Mr. Block’s quip notwithstanding, the fact is that humans have been extending their minds for millenniums. Ancient peoples frequently engaged in offloading their mental contents and augmenting their brainpower with external resources, as evidenced by objects they left behind. Sumerians employed clay tokens to keep track of livestock and other goods when trading; Incas tied knots in long cords, called quipus, to memorialize events; administrators and merchants across a broad swath of the ancient world used abacuses and counting boards. Likewise, the notes and sketches of artists and thinkers over the centuries bear testament to “that wordless conversation between the mind and the hand,” as the psychologist Barbara Tversky puts it in “Mind in Motion: How Action Shapes Thought.” When Leonardo da Vinci sought to understand “the flow of blood in arteries and the flow of water in rivers,” Dr. Tversky observed elsewhere, he leaned on both body and space, using “the actions of his hand as he drew as if they were mirroring the actions of nature.” And of course, history offers a rich record of how groups of people thinking together have managed to do what a single person could not. The unaccommodated brain is a poor, bare thing indeed. Mental extension is involved in most of humanity’s feats, from the transcendent to the mundane.

We, too, extend our minds, but not as well as we could. We do it haphazardly, without much intention or skill — and it’s no wonder this is the case. Our efforts at education and training, as well as management and leadership, are aimed principally at promoting brain-bound thinking. Beginning in elementary school, we are taught to sit still, work quietly, think hard — a model for mental activity that will dominate during the years that follow, through high school and college and into the workplace. The skills we develop and the techniques we are taught are mostly those that involve using our individual, unaided brains: committing information to memory, engaging in internal reasoning and deliberation, mustering our mental powers from within. Compared to the attention we lavish on the brain, we expend relatively little effort on cultivating our ability to think outside the brain.

The limits of this approach have become painfully evident. The days when we could do it all in our heads are over. Our knowledge is too abundant, our expertise too specialized, our challenges too enormous. The best chance we have to thrive in the extraordinarily complex world we’ve created is to allow that world to assume some of our mental labor. Our brains can’t do it alone.

This article can be found on the New York Times website by clicking this link.