Pulling into a parking spot at work, you realize you have no recollection of the drive that got you there. While reading a news story, you arrive at the bottom of the page, frustrated that you have no idea what you just read. In midconversation you suddenly become aware that you have missed what the person speaking to you has said.
These episodes are symptoms of a distracted mind. You were thinking about a project idea while driving, reliving a troubling memory while attempting to read, envisioning a weekend getaway with friends during a conversation with your co-worker. Whether the mind journeyed to the future or to the past, whether the thoughts that whisked you away were useful, unpleasant or pleasant, the consequences were the same. You missed the experience of the moment as it was unfolding. Your mind drifted into mental time travel.
Away from the Now
Mental time travel evolved to advantage our survival. By reexperiencing the past, we can learn from it, and by preexperiencing the future, we can prepare for it. Both retrospection (rewinding events in the mind) and prospection (fast-forwarding them) rely on our brain’s capacity for mental simulation. And based on the brain nodes and networks that carry out simulation, chief among them regions of the prefrontal cortex, we can glean that this is a recently gained evolutionary development. How does mental simulation work, and what does it have to do with stress and mind wandering (which is distinct from deliberate daydreaming)?
Before we discuss that, let’s test our simulation abilities. Imagine being handed a delicious chocolate cupcake with creamy white frosting. You lift it up to your mouth, anticipating the rich chocolate flavor. But as you go to take a bite, I inform you that the frosting is made of cod-liver oil and cauliflower. The likely response: Yuck!
Let’s break down what happened. The initial description of the cupcake prompted a mental image in your mind, and your attention transported you into a simulated experience, perhaps so vivid that you could almost taste the cupcake and feel your mouth watering. You recoiled as soon as you “pretasted” the seemingly disgusting cod-liver oil concoction.
Simulations have the power to transport our attention out of the present moment while simultaneously altering our cognitive, emotional and physiological responses in the now. The same mental powers that drove up your salivary response when you “previewed” a cupcake can drive down your mood, focus and thinking if you preview a threatening episode over and over. Worse, they can stimulate the pituitary gland to release more stress hormones. Herein lies the downside of this evolutionary advance: as our attention journeys to an alternative reality, our mind and body respond as if that reality were unfolding in the here and now.
Research suggests that this type of mental meandering away from our present moment has many deleterious consequences for our minds, bodies and relationships. Such mind wandering can spike during stressful times in our lives, be they acute or chronic events. And as mind wandering increases in the form of more frequent rumination or worrying, our experience of stress expands, creating a spiral of thinking that reduces our concentration while increasing our levels of stress hormones.
In my laboratory at the University of Miami, we study the human brain’s attention system. To investigate whether and how stress influences attention, we partner with people in some of the most extreme, high-demand lines of work: medical professionals, firefighters, soldiers and elite athletes. They need to deploy their attention—and do it well—in extraordinarily high-stakes circumstances where their decisions could impact many people. One group we have worked with extensively is the U.S. military. Whether and how people in this demographic pay attention can be a matter of life or death. For all of us, attention is a powerful force that shapes our lives far more than we realize.
Our attention influences our perceptual, emotional, decisional and social functioning and therefore affects our sense of fulfillment and accomplishment. Many of our participants experience protracted high-stress intervals, such as soldiers enduring predeployment training or military deployment, and we wondered what happens to attention over these intervals. We learned that, similar to what is observed in lab-based studies, experiencing stress in the field indeed causes attentional performance to decline while increasing mind wandering. This prompted the next important question: Can attention be trained to resist stress-related increases in mind wandering?
My group first considered mindfulness training as a potential solution in the early 2000s. If mentally zooming into the past or future was the root cause of “attentional hijacking,” then perhaps the most effective antidote would be a training regimen that emphasized a present-centered attentional stance.
Antidote to a Wandering Mind
The opposite of a wandering mind is a mindful one. Mindfulness is a mental mode characterized by attention to the present moment without evaluation or emotional reaction to it. Eastern cultures have proffered various forms of meditation as a solution to the conundrum of human suffering. Ancient texts detail precise training exercises to cultivate specific mental qualities. One form of meditation, which we now call mindfulness meditation, instructs practitioners to pay attention to ongoing perceptual experience rather than conceptual trains of thought. People have been engaging in mindfulness exercises for millennia, claiming improved mental clarity and calm—and even greater longevity.
Thousands of articles lay out evidence that training to become more mindful reduces psychological stress and improves both mental and physical health, alleviating depression, anxiety, loneliness and chronic pain [see “Capturing Attention” below]. Many workplaces and medical centers now offer mindfulness-based programs to improve well-being. There has been an explosive proliferation of mindfulness training modalities beyond this as well, from apps and asynchronous online trainings to trainer-led in-person and remote programs.
One broad category of mindfulness exercises is focused-attention practices. These practices guide individuals to select a specific sensation tied to, for example, breathing and direct attention to that sensation. Instructions next encourage the practitioner to notice when his or her mind has wandered away from that attentional target and, when mind wandering is registered, to simply return attention back to the immediate breath-related sensations.
A second category emphasizes receptive-attention practices, which coach practitioners to engage in open monitoring. They are to watch what enters and then drops out of conscious awareness moment by moment. Think of hearing the faint sound of a fire truck’s siren in the distance. The sound becomes louder as the truck approaches, then fainter again as it passes. You may notice that the siren is initially part of a vast sea of sounds and later the most salient sound, only to fade into the background again. Thoughts, emotions and other sensations may similarly grow and diminish as we remain in a watchful monitoring mode.
One of the best-studied mindfulness training programs was developed by Jon Kabat-Zinn of the University of Massachusetts Medical School in the late 1970s. The program, called mindfulness-based stress reduction (MBSR), introduces participants to both these broad categories of exercise. It is offered over eight weeks and involves weekly group meetings with a qualified trainer, as well as daily homework practices of 45 minutes a day.
As its name highlights, MBSR aims to promote stress reduction, as well as treatment for those suffering from any one of myriad ailments. The application and reach of MBSR have mushroomed over the past decade, and it has guided many mindfulness-based interventions (MBIs) designed to improve the health of the body, the mind and relationships. These practices have been shown to alleviate stress-related inflammatory and cardiovascular diseases, as well as psychological disorders and diseases such as anxiety and depression. In addition, several studies report that MBIs improve interpersonal dynamics and team cohesion in the workplace.
From a clinical perspective, although the field is admittedly in its infancy, the evidence is promising regarding the somatic, psychological and social benefits of mindfulness training. Yet my interest is from a cognitive neuroscience perspective: If mindfulness does work, how does it work? A review of mindfulness training exercises showed that they certainly highlight attention, but they also emphasize the detection of mind wandering. We needed to put mindfulness to the test in a manner that would allow us to assess both these components.
To do this, we used the “sustained attention to response” task, or SART. This test was developed in the late 1990s, and, as the name suggests, it tests a person’s ability to sustain attention. Participants sit in front of a computer screen where a number appears for half a second and then vanishes. A half-second later, another number appears and then vanishes, and so on for 20 minutes. Their job: press the space bar every time a number appears—unless the number is three. By design, the number three appears only 5 percent of the time.
This test engages the three main subsystems of attention: orienting, or directing attention; alerting, or noticing events; and executive attention, or managing goals and performance. You orient attention to the screen, focusing on each number as it flickers; stay alert for the appearance of the number three; and use executive attention to make sure you are following the instructions and pressing the key only when you should.
It sounds simple, but it is not easy. Most participants do not perform well on this task. Why? They quickly go on autopilot, lost in their own mental simulations, and press the space bar no matter what number appears. Their attention goes off task. We know this because we stopped the experiment and asked them every now and then. Their minds wandered numerous times throughout the experiment, and during those episodes, their performance suffered compared with when they stayed on task.
We have used this experiment in many studies to see whether mindfulness training strengthens attention and reduces mind wandering in individuals experiencing intervals of high demand such as an academic semester or military deployment. We found that for a variety of groups ranging from undergraduate students to elite military units, mindfulness training indeed benefited SART performance. Compared with those who received no training, those in the mindfulness training groups had higher SART accuracy scores and less mind wandering over time.
In a 2020 study published in the Journal of Cognitive Enhancement, Frederikke Piil, then at the University of Southern Denmark, and her colleagues examined the consequences of acute stress and mindfulness training on SART performance in 48 university students and staff members. All participants were provided with one of two apps that required their engagement in daily practices over an interval of one month. One group used a mindfulness app to practice mindfulness exercises, and the other group used a cognitive training app to complete simple cognitive exercises.
To determine a baseline at the start of the experiment, participants first completed a cold pressor task—they submerged their nondominant hand in a tank of circulating ice water until it became too uncomfortable to keep it there. This task has been found to reliably increase stress as measured by increases in arousal of the sympathetic nervous system (for example, increased heart rate, blood pressure and stress hormones). Afterward they completed the SART. They returned a month later and once again completed the cold pressor task followed by the SART. Only the mindfulness group improved in their SART performance, and the more they used the mindfulness app, the more their performance benefited.
Because attention and mind wandering are known to correspond with academic performance, Clemens C. Bauer of the Massachusetts Institute of Technology and his colleagues used the SART test in combination with brain imaging in school-aged children. In their study, published in 2020 in Human Brain Mapping, half of 99 sixth graders received mindfulness training, and the other half received a computer-coding course.
After training, only the mindfulness group demonstrated preserved SART performance over the demanding academic semester. This group showed increased anticorrelation between activity in the central executive network, a key brain network for attention, and activity in the default mode network, known to be activated during mental simulations and mind wandering. Greater anticorrelation between these two networks after training indicates that only members of the mindfulness group improved in their cognitive control. These results suggest that mindfulness training may help children to stay focused and complete the task at hand.
Interestingly, recent work by Lukas Lenhart of the Medical University of Innsbruck in Austria and his colleagues in which participants received seven weeks of mindfulness training revealed altered brain structure in specific nodes tied to attention and mind wandering. In that study, published in 2020 in Behavioural Brain Research, 27 participants received an MRI scan before and after the mindfulness course. The researchers observed increased gray matter density in subjects’ frontal lobe nodes within attentional networks, as well as decreases in gray matter density within nodes of the default mode.
Together these studies suggest that mindfulness training may provide a type of mental armor during times of protracted and acute stress and can serve to boost focus. It appears to benefit both children and adults, resulting in functional and structural brain changes. Such training allows us to break free from a wandering mind that can distract us from the task at hand and sour our mood. With our full capacity available to us, all aspects of our functioning that are fueled by attention will benefit, be it our ability to think, feel or connect.
Prescription for the Brain
Efforts to become more mindful could make a considerable dent in human suffering. Working mindfulness practices into your daily routine may bring benefits similar to those of physical exercise. Indeed, as with physical exercise, mindfulness exercises are stress-protective, and the more you do, the more you benefit. As an antidote to an ambling mind, negative mood and stress, such mental workouts may have the potential to help virtually everyone live a happier, healthier and more fulfilled life. Students or athletes who want to boost their performance, for example, and parents, teachers or caregivers wishing to be more attentive to others’ needs may all find mindfulness training useful. Such training may be particularly essential, however, for soldiers, first responders, critical care nurses and physicians, and air-traffic controllers, whose ability to control and monitor their attention may be a matter of life or death.
A key insight from our research is that merely learning about the damaging effects of stress or the benefits, history or mechanisms of mindfulness training did not lead to attentional improvements. Only engaging in regular mindfulness practice did. In studies across military service members and athletes, among others, we found a dose-response effect; the more practice people engaged in, the more they benefited. But conversely, we also found that when we assigned 30 minutes of daily practice, most time-pressured participants simply did not comply. Some did the 30 minutes; others did none. We pursued this “dosing question” across several studies to arrive at a daily practice prescription to which participants were willing to adhere: 12 to 15 minutes a day five days a week. When this group followed through, we saw beneficial effects on their attention. The research continues, and many more studies will be required.
With evidence of its benefits mounting come new challenges for mindfulness training. How can access be scaled up and meet the needs of specific groups? Based on our past research, my colleague Scott Rogers and I created a short-form program called mindfulness-based attention training (MBAT). Once we found the core program to be effective, we developed train-the-trainer methods to address scalability challenges. MBAT’s modular structure and exercises allow for flexibility so the program can be customized for a variety of groups, from soldiers to medical students, athletes, business professionals, first responders and teachers. The linchpin of the program’s success is the competency of the trainers. We are finding that more so than prior expertise in mindfulness, successful trainers must have familiarity with the cultural norms, sensitivities and stressors that a particular community faces.
The scientific literature on mindfulness training is still in its infancy, and many scientists are calling for more rigorous research methods such as standardized programs and better placebo-controlled designs. Yet the promise of mindfulness continues to generate much interest. The overarching message seems to be that the more time spent engaging in such training, the more benefits in attention. No matter our profession, as we learn to grab hold of our attention and become more meta-aware of our moment-to-moment experience, we gain the power to intervene in support of our own happiness and health.