The Extended Mind: The Power of Thinking Outside the Brain

by Annie Murphy Paul

Our culture insists that the brain is the sole locus of thinking, a cordoned-off space where cognition happens, much as the workings of my laptop are sealed inside its aluminum case. This book argues otherwise: it holds that the mind is something more like the nest-building bird I spotted on my walk, plucking a bit of string here, a twig there, constructing a whole out of available parts. For humans these parts include, most notably, the feelings and movements of our bodies; the physical spaces in which we learn and work; and the other minds with which we interact—our classmates, colleagues, teachers, supervisors, friends.

Much less attention has been paid to the ways people use the world to think: the gestures of the hands, the space of a sketchbook, the act of listening to someone tell a story, or the task of teaching someone else. These “extra-neural” inputs change the way we think; it could even be said that they constitute a part of the thinking process itself.

This book aims to exhume that hidden saga, reclaiming its rightful place in any full accounting of how the human race has achieved its remarkable feats of intellect and creativity.

Research emerging from three related areas of investigation has convincingly demonstrated the centrality of extra-neural resources to our thinking processes. First, there is the study of embodied cognition, which explores the role of the body in our thinking: for example, how making hand gestures increases the fluency of our speech and deepens our understanding of abstract concepts. Second, there is the study of situated cognition, which examines the influence of place on our thinking: for instance, how environmental cues that convey a sense of belonging, or a sense of personal control, enhance our performance in that space. And third, there is the study of distributed cognition, which probes the effects of thinking with others—such as how people working in groups can coordinate their individual areas of expertise (a process called “transactive memory”), and how groups can work together to produce results that exceed their members’ individual contributions (a phenomenon known as “collective intelligence”).

In 1995 Clark had co-written a paper titled “The Extended Mind,” which opened with a deceptively simple question: “Where does the mind stop and the rest of the world begin?” Clark and his coauthor, philosopher David Chalmers, noted that we have traditionally assumed that the mind is contained within the head—but, they argued, “there is nothing sacred about skull and skin.” Elements of the world outside may effectively act as mental “extensions,” allowing us to think in ways our brains could not manage on their own.

Clark and Chalmers initially focused their analysis on the way technology can extend the mind—a proposal that quickly made the leap from risibly preposterous to self-evidently obvious, once their readers acquired smartphones and began offloading large chunks of their memories onto their new devices. (Fellow philosopher Ned Block likes to say that Clark and Chalmers’s thesis was false when it was written in 1998 but subsequently became true—perhaps in 2007, when Apple introduced the first iPhone.)

Over the course of many more published papers and books, Clark mounted a broad and persuasive argument against what he called the “brainbound” perspective—the view that thinking happens only inside the brain—and in favor of what he called the “extended” perspective, in which the rich resources of our world can and do enter into our trains of thought.

they also supply guidance on how to offload, externalize, and dynamically interact with our thoughts—a much more effective approach than doing it all “in our heads.”

It’s my hope that this book will cast a different light, bring a bracing gust of fresh air to the thinking we do as students and workers, as parents and citizens, as leaders and creators.

The brainbound paradigm now so dominant is clearly inadequate to the task; everywhere we look we see problems with attention and memory, with motivation and persistence, with logical reasoning and abstract thinking. Truly original ideas and innovations seem scarce; engagement levels at schools and in companies are low; teams and groups struggle to work together in an effective and satisfying way.

Thinking outside the brain means skillfully engaging entities external to our heads—the feelings and movements of our bodies, the physical spaces in which we learn and work, and the minds of the other people around us—drawing them into our own mental processes. By reaching beyond the brain to recruit these “extra-neural” resources, we are able to focus more intently, comprehend more deeply, and create more imaginatively—to entertain ideas that would be literally unthinkable by the brain alone.

by using the movements of our hands to understand and express abstract concepts, for example, or by arranging our workspace in ways that promote idea generation, or by engaging in social practices like teaching and storytelling that lead to deeper understanding and more accurate memory.

But when we clear away the hype, we confront the fact that the brain’s capacities are actually quite constrained and specific. The less heralded scientific story of the past several decades has been researchers’ growing awareness of the brain’s limits. The human brain is limited in its ability to pay attention, limited in its capacity to remember, limited in its facility with abstract concepts, and limited in its power to persist at a challenging task.

It’s not a matter of individual differences in intelligence; it’s a matter of the character of the organ we all possess, its biological nature and its evolutionary history. The brain does do a few things exquisitely well—things like sensing and moving the body, navigating through space, and connecting with other humans. These activities it can manage fluently, almost effortlessly. But accurately recalling complex information? Engaging in rigorous logical reasoning? Grasping abstract or counterintuitive ideas? Not so much.

The modern world is extraordinarily complex, bursting with information, built around non-intuitive ideas, centered on concepts and symbols. Succeeding in this world requires focused attention, prodigious memory, capacious bandwidth, sustained motivation, logical rigor, and proficiency with abstractions. The gap between what our biological brains are capable of, and what modern life demands, is large and getting larger each day. With every experimental discovery, the divide between the scientific account of the world and our intuitive “folk” understanding grows more pronounced. With every terabyte of data swelling humanity’s store of knowledge, our n...

We urge ourselves and others to grit it out, bear down, “just do it”—to think harder.

Confronted by its limits, we may conclude that we ourselves (or our children or our students or our employees) are simply not smart enough, or not “gritty” enough. In fact, it’s the way we handle our mental shortcomings—which are, remember, endemic to our species—that is the problem. Our approach constitutes an instance of (as the poet William Butler Yeats put it in another context) “the will trying to do the work of the imagination.” The smart move is not to lean ever harder on the brain but to learn to reach beyond

Beginning in elementary school, we are taught to sit still, work quietly, think hard—a model for mental activity that will prevail during all the years that follow, through high school and college and into the workplace. The skills we develop and the techniques we are taught are those that involve using our heads: committing information to memory, engaging in internal reasoning and deliberation, endeavoring to self-discipline and self-motivate.

Teachers and managers don’t demonstrate how abstract ideas can be turned into physical objects that can be manipulated and transformed in order to achieve insights and solve problems. Employees aren’t shown how the social practices of imitation and vicarious learning can shortcut the process of acquiring expertise. Classroom groups and workplace teams aren’t coached in scientifically validated methods of increasing the collective intelligence of their members. Our ability to think outside the brain has been left almost entirely uneducated and undeveloped.

This oversight is the regrettable result of what has been called our “neurocentric bias”—that is, our idealization and even fetishization of the brain—and

Emo Philips has remarked: “I used to think that the brain was the most wonderful organ in my body. Then I realized who was telling me this.”)

The introduction of the ENIAC was not just a milestone in the history of technology. It was a turning point in the story of how we understand ourselves. In its early days, Mauchly and Eckert’s invention was frequently compared to a human brain. Newspaper and magazine articles described the ENIAC as a “giant electronic brain,” a “robot brain,” an “automatic brain,” and a “brain machine.”

From this inference emerges a second: the human brain has attributes, akin to gigabytes of RAM and megahertz of processing speed, that can be easily measured and compared. Following on these is the third and perhaps most significant supposition of all: that some brains, like some computers, are just better; they possess the biological equivalent of more memory storage, greater processing power, higher-resolution screens.

At the center of it all is a metaphor: the brain as muscle. The mind, in this analogy, is akin to a biceps or a quadriceps—a physical entity that varies in strength among individuals. The comparison has been incorporated into another hugely popular concept originating in academic psychology: “grit.” Angela Duckworth, the University of Pennsylvania psychologist who defines grit as “perseverance and passion for long-term goals,” echoes Dweck in her own book. “Like a muscle that gets stronger with use, the brain changes itself when you struggle to master a new challenge,” she wrote in the best-selling Grit, published in 2016.

These two metaphors—brain as computer and brain as muscle—share some key assumptions. To wit: the mind is a discrete thing that is sealed in the skull; this discrete thing determines how well people are able to think; this thing has stable properties that can easily be measured, compared, and ranked. Such assumptions feel comfortably familiar; indeed, they weren’t particularly novel even at the moment they were first proposed. For centuries, brains had been likened to machines—to whichever appliance of the time appeared most advanced: a hydraulic pump, a mechanical clock, a steam engine, a telegraph machine.

The computer and muscle analogies fit neatly with our society’s emphasis on individualism—its insistence that we operate as autonomous, self-contained beings, in possession of capacities and competencies that are ours alone.

The belief that some core quantity of intelligence resides within each of our heads fits with a pattern of thought, apparently universal in humans, that psychologists call “essentialism”—that is, the conviction that each entity we encounter possesses an inner essence that makes it what it is. “Essentialism shows up in every society that has been studied,” notes Yale University psychology professor Paul Bloom. “It appears to be a basic component of how we think about the world.” We think in terms of enduring essences—rather than shifting responses to external influences—because we find such essences easier to process mentally, as well as more satisfying emotionally. From the essentialist perspective, people simply “are” intelligent or they are not.

thought happens not only inside the skull but out in the world, too; it’s an act of continuous assembly and reassembly that draws on resources external to the brain. For another: the kinds of materials available to “think with” affect the nature and quality of the thought that can be produced. And last: the capacity to think well—that is, to be intelligent—is not a fixed property of the individual but rather a shifting state that is dependent on access to extra-neural resources and the knowledge of how to use them.

First, as to that growing need to think outside the brain: as many of us can readily recognize—in the accelerated pace of our days and the escalating complexity of our duties at school and work—the demands on our thinking are ratcheting up. There’s more information we must deal with. The information we have to process is coming at us faster. And the kind of information we must deal with is increasingly specialized and abstract. This difference in kind is especially significant. The knowledge and skills that we are biologically prepared to learn have been outstripped by the need to acquire a set of competencies that come far less naturally and are acquired with far more difficulty. David Geary, a professor of psychology at the University of Missouri, makes a useful distinction between “biologically primary” and “biologically secondary” abilities. Human beings, he points out, are born ready to learn certain things: how to speak the language of the local community, how to find their way around a familiar landscape, how to negotiate the challenges of small-group living. We are not born to learn the intricacies of calculus or the counterintuitive rules of physics; we did not evolve to understand the workings of the financial markets or the complexities of global climate change. And yet we dwell in a world where such biologically secondary capacities hold the key to advancement, even survival. The demands of the modern environment have now met, and exceeded, the limits of the bi...

Continual engagement with the mental rigors of modern life—along with improving nutrition, rising living conditions, and reduced exposure to infectious disease and other pathogens—produced a century-long climb in average IQ score, as measured by intelligence tests taken by people all over the globe. But this upward trajectory is now leveling off. In recent years, IQ scores have stopped rising, or have even begun to drop, in countries like Finland, Norway, Denmark, Germany, France, and Britain. Some researchers suggest that we have now pushed our mental equipment as far as it can go. It may be that “our brains are already working at near-optimal capacity,” note Nicholas Fitz and Peter Reiner, writing in the journal Nature.

A 2017 study of Lumosity determined that “training appears to have no benefits in healthy young adults”; similarly dismal results have been reported for older individuals. In 2016, Lumosity was forced to pay a $2 million fine for deceptive advertising to the US Federal Trade Commission.

Clark and Chalmers went on to offer an unconventional response. The mind does not stop at the standard “demarcations of skin and skull,” they argued. Rather, it is more accurately viewed as “an extended system, a coupling of biological organism and external resources.”

Traditional notions of what makes an expert are highly brainbound, focused on internal, individual effort (think of the late psychologist Anders Ericsson’s famous finding that mastery in any field requires “10,000 hours” of practice). The literature on the extended mind suggests a different view: experts are those who have learned how best to marshal and apply extra-neural resources to the task before them.

experts are less likely to “use their heads” and more inclined to extend their minds—a habit that the rest of us can learn to emulate on our way to achieving mastery.

We extend beyond our limits, not by revving our brains like a machine or bulking them up like a muscle—but by strewing our world with rich materials, and by weaving them into our thoughts.

important to recognize that the world is full of far more information than our conscious minds can process. Fortunately, we are also able to collect and store the volumes of information we encounter on a non-conscious basis.

This trove of data remains mostly under the surface of consciousness, and that’s usually a good thing. Its submerged status preserves our limited stores of attention and working memory for other uses.

A study led by cognitive scientist Pawel Lewicki demonstrates this process in microcosm. Participants in Lewicki’s experiment were directed to watch a computer screen on which a cross-shaped target would appear, then disappear, then reappear in a new location; periodically they were asked to predict where the target would show up next. Over the course of several hours of exposure to the target’s movements, the participants’ predictions grew more and more accurate. They had figured out the pattern behind the target’s peregrinations. But they could not put this knowledge into words, even when the experimenters offered them money to do so. The subjects were not able to describe “anything even close to the real nature” of the pattern, Lewicki observes. The movements of the target operated according to a pattern too complex for the conscious mind to accommodate—but the capacious realm that lies below consciousness was more than roomy enough to contain it. “Nonconscious information acquisition,” as Lewicki calls it, along with the ensuing application of such information, is happening in our lives all the time. As we navigate a new situation, we’re scrolling through our mental archive of stored patterns from the past, checking for ones that apply to our current circumstances. We’re not aware that these searches are under way; as Lewicki observes, “The human cognitive system is not equipped to handle such tasks on the consciously controlled level.” He adds, “Our conscious thinking...

Yet interviews with the participants showed that they had no awareness of why they had begun choosing some decks over others until late in the game, long after their skin conductance had started flaring. By card 10 (about forty-five seconds into the game), measures of skin conductance showed that their bodies were wise to the way the game was rigged. But even ten turns later—on card 20—“all indicated that they did not have a clue about what was going on,” the researchers noted. It took until card 50 was turned, and several minutes had elapsed, for all the participants to express a conscious hunch that decks A and B were riskier.

The body not only grants us access to information that is more complex than what our conscious minds can accommodate. It also marshals this information at a pace that is far quicker than our conscious minds can handle.

HERE, THEN, is a reason to hone our interoceptive sense: people who are more aware of their bodily sensations are better able to make use of their non-conscious knowledge.

Others include the anchoring effect, in which we rely too heavily as a point of reference on the first piece of information we encounter; the availability heuristic, in which we overestimate the likelihood of events that come more readily to mind; and the self-serving bias, in which our personal preferences incline our beliefs in an overly optimistic direction.

The body acts as a critical conduit, supplying the brain with the visceral information it lacks. It does so in this way: When interacting with other people, we subtly and unconsciously mimic their facial expressions, gestures, posture, and vocal pitch. Then, via the interoception of our own bodies’ signals, we perceive what the other person is feeling because we feel it in ourselves. We bring other people’s feelings onboard, and the body is the bridge. In an act akin to taking a bite off our partner’s plate, or borrowing an earbud to hear the song our friend is listening to, we are sampling their emotions.

When they compared the “detection rates” they achieved while sitting and while moving, the results were clear: radiologists who remained seated spotted an average of 85 percent of the irregularities present in the images, while those who walked identified, on average, fully 99 percent of them.

A different set of research findings helps to explain the radiologists’ results. When we’re engaged in physical activity, our visual sense is sharpened, especially with regard to stimuli appearing in the periphery of our gaze. This shift, which is also found in non-human animals, makes evolutionary sense: the visual system becomes more sensitive when we are actively exploring our environment. When our bodies are at rest—that is, sitting still in a chair—this heightened acuity is dialed down.

The human brain is approximately three times larger than it “should” be, given the dimensions of the human body; according to fossil evidence, a remarkable expansion in the size of the brain took place about 2 million years ago.

another explanation has been put forth: “At the same time as brain size began to increase in the human lineage, aerobic activity levels appear to have changed dramatically,” notes David Raichlen, a professor of biological sciences at the University of Southern California. “Human ancestors transitioned from a relatively sedentary ape-like existence to a hunting and gathering lifestyle which required an increased amount of physical activity compared to earlier hominins.”

This approach has its limits; in particular, research demonstrates that our memory for what we have heard is remarkably weak. Our memory for what we have done, however—for physical actions we have undertaken—is much more robust. Linking movement to the material to be recalled creates a richer and therefore more indelible “memory trace” in the brain. In addition, movements engage a process called procedural memory (memory of how to do something, such as how to ride a bike) that is distinct from declarative memory (memory of informational content, such as the text of a speech). When we connect movement with information, we activate both types of memory, and our recall is more accurate as a result—a phenomenon that researchers call the “enactment effect.”

The implications of the Noices’ research are clear. First: information is better remembered when we’re moving as we learn it. This is the case even when the movement is not a literal enactment of the meaning of the information to be recalled but simply a movement of the body, meaningfully related to the information and made at the same time the information is absorbed. Second: information that has become associated with a movement is better remembered when we can reproduce that same movement later, when we’re calling it up from memory. This may be possible in some situations—for example, when giving a speech for which we have practiced accompanying gestures—but moving while learning is still beneficial even when those movements can’t be replicated at the point of recall (during an exam, for instance).

The research on using movement to enhance thinking identifies four types of helpful motion: congruent movements, novel movements, self-referential movements, and metaphorical movements. The first of these, congruent movements, express in physical form the content of a thought. With the motions of our bodies, we enact the meaning of a fact or concept. Congruent movements are an effective way to reinforce still tentative or emerging knowledge by introducing a corporeal component into the process of understanding and remembering. A familiar example is moving the body along a number line: children who are learning about math benefit from taking steps on an oversized number line placed on the floor as they count or as they carry out procedures like addition and subtraction.