MINDFULNESS PRACTICE AND ATTENTION
In the previous chapter, we saw that more permanent changes in the meditating brain include gray matter changes in regions associated with the salience network and the executive control network, general body awareness, emotion regulation, the stress response, and the linkages between them. From this, we might expect changes in corresponding properties of heart and mind—sharpened attention perhaps, improved vigilance, changes in body awareness, maybe changes in personality and how you experience your self, maybe an enhanced capability to deal with negative emotions and life’s small (or even larger) frustrations.
As we saw in Chapter 1, modern Western definitions of mindfulness highlight the concept of attention: Mindfulness is “paying attention in a particular way: on purpose, in the present moment, and non-judgmentally”1—from the point of view of mindfulness, everything follows from following the breath.2 It makes sense, then, to first look at how mindfulness training impacts attention before we look at changes in other aspects of a person’s psychological make-up.
Note that we are switching methodological gears again. Studies probing the meditating brain in action (Chapters 2 and 3), as we saw, mostly test very long-term Buddhist meditators (many of them nuns or monks). Studies on structural changes in the brains of meditators (Chapter 4) all used laypeople, but still about half of them practiced within a religious, Buddhist context. On average, these people had less than half the lifetime experience of the volunteers in the brain activation studies; these studies also included participants from “secular” (or, if you prefer, “clinical”) meditation programs—MBSR or MBSR-like.
The set of studies in this chapter lower the meditative achievement of the average research participant a little more and have a much higher proportion of participants from these secular programs. Part of the reason for this shift is pragmatism on the part of researchers: Such volunteers are generally easier to find, and it is now perfectly feasible to include them in these studies. That is, testing people on attention or other psychological measurements in a psychology lab doesn’t require people with the amazing feats of unshakeable meditation required for the studies in the previous chapters.
This shift, of course, makes it hard to directly link the studies on attention to studies on the meditating brain—this is a different group of people, with a very different level of experience. We simply don’t know if the changes in attention we observe in these less experienced meditators bear any relationship to the changes we’ve noted in the brains of the very advanced practitioners. On the other hand, the research volunteers here look a lot more like me and (perhaps) you, and so the results from the studies in this chapter are more likely to be applicable to the average practitioner of mindfulness. Our brains might not necessarily look like nuns’ or monks’ brains (frankly, we don’t know), but our feats of attention likely look like the ones covered in this chapter.
As in previous chapters, my emphasis here—all in the service of avoiding bias—is on looking at results of batches of studies on a particular topic, preferably relying on results from meta-analyses, rather than zooming in on one particular study.
The largest meta-analysis on the psychological effects of meditation is by Peter Sedlmeier and colleagues.3 This analysis gathered a total of 163 studies that examined the effects of meditation on all kinds of psychological variables. All of these studies compared performance of a group of meditators (who could be either seasoned or beginning, or anything in between, but most of them were fresh out of an MBSR-type program) with that of a group of control subjects, that is, people who do not meditate. They found 22 studies that focused on attention. The average effect in these studies was 0.58 SD, which is quite respectable. It implies that the average meditator is more attentive than 72% of nonmeditators. In a follow-up study, Ebert and Sedlmeier4 refined the Sedlmeier et al. analysis to include only studies on mindfulness meditation (in practice, that meant removing all studies on Transcendental Meditation® from the larger meta-analysis); the remaining eight studies had a very similar effect size—0.63 SD. The average mindfulness meditator has stronger attention skills than 73% of nonmeditators.
Attention, of course, is not a single skill. It’s quite different to focus your attention on just one thing and exclude all distractors than to remain sharp and concentrated for a long time, and it is different still to divide your attention between two or more tasks at the same time. In Chapter 3, I introduced a model devised by Wendy Hasenkamp and colleagues5 that captures the different types of attention engaged in meditation well: It starts with the inevitable cycle of mind-wandering (a lack of control over attention), which is punctured by the awareness that you are mind-wandering, followed by bringing your attention back, and finally sustaining it for a while—until your mind wanders off again. Attention here, then, serves three functions.
The first is noticing and alerting, that is, detecting when the mind wanders; this function is associated with the salience network. Note that Kabat-Zinn’s definition highlights a particular quality of this noticing and alerting attention, namely a sense of openness and lightness (the “nonjudgmentally” in his definition). This is an aspect of attention that is not typically studied by psychologists.
The second is controlling attention, that is, returning your focus to where it should be; this function is associated with the executive attention network.6 This aspect of attention is also often called “concentration.”
The third function is sustaining and stabilizing attention, that is, keeping awareness focused on what it needs to be focused on; this is done by a subset of the executive attention network.
It makes sense to group studies according to these three categories. I examine the evidence for changes in attentional control first, because most studies on the effects of mindfulness and meditation on attention have focused on this particular aspect.
Psychologists use many tasks to measure attentional control, but the one that is perhaps most popular is a simple, yet devilish little test I introduced you to in Chapter 2—the Stroop task. Recall that in the Stroop task you are shown a series of color words (words like “red,” “green,” etc.). Each word is printed in a different color than the word it refers to (e.g., the word “red” can be printed in green, the word “green” may be in blue, and so on). Your task is to name the color of the ink, not the color the word refers to (so, in the previous example, you would say: “green,” “blue,” and not “red,” “green”). This is hard—it slows you down, and you might make a few errors, maybe even producing blended words like “bleen” or “grue.” The reason this task is difficult is that reading is an automatic and “obligatory” process; that is, once you see a word or a sentence, you can’t help but read it. (Try it: Next time you see a billboard, try not to read what it says. Can you do it?) This automatic process of reading the word interferes with you naming the ink color. To do well on the Stroop task, you clearly need to pay attention and stay focused on the task and go against your natural tendency to prioritize reading. The Stroop task is used so often because it works and because is very easy to administer—all you need is paper and a stopwatch (although it is now often done on computers), and it takes less than a minute.
I was able to locate nine studies on the effects of meditation and mindfulness practice on the Stroop test7; the total number of meditators involved was small—221. The average effect size for these eight studies was 0.45 SD. The average meditator does better on the Stroop task than 67% of the general public.
In three of the nine studies, participants were new meditators who learned to meditate over the course of the study (accumulating between 18 and 40 hours of experience); the effect size for these three studies was 0.42 SD. The other studies compared seasoned meditators (with typically a few years of experience) with nonmeditators; this resulted in a very similar effect size, namely 0.48 SD.
The similarity in effects suggests two things. One conclusion—very encouraging indeed—is that not much meditation practice is needed to increase concentration. Even 20 to 40 hours or so of practice results in measurable changes in control over attention.
The second conclusion is that you don’t need to have many years of meditation practice to generate the kind of concentration needed for the Stroop. What matters more is the amount of daily practice. One study did find that the number of years of meditation correlated (rather modestly) with the Stroop effect (a correlation of –.27; people who had been meditating longer were less bothered by the color–word conflict), but the same study also found that how often you meditate had about the same effect (the correlation was –.23). (The first correlation can be explained by the fact that more seasoned meditators also tend to spend more time on the cushion.) Another study only found a dose–response relationship with the number of minutes practiced per day (correlation of –.17, again quite modest), not with total hours of lifetime meditation experience.8
Control can be measured with other tasks besides the Stroop task. I do not go into detail for all of these tasks here; I’ll just mention one: the go/no-go task. In this task, you see numbers flash by on a screen, one at a time, at a fast clip. Your job is to press the button as quickly as you can whenever you see a number appear (that’s the “go” part), except when you see a particular number, say, the number 2 (that is the “no-go” part). Being able to keep yourself from pressing the button when you are not supposed to is a powerful measure of how well you are able to control attention.
I found five studies on attentional control measures other than Stroop9; these yielded an average effect size of 0.23 SD. One study10 found a strong correlation (r = .52) between the number of minutes practiced over the past eight weeks and how good people were at not making errors on a go/no-go task.
Combining the effect of all studies that included measures of attentional control (there were 10 of those), I obtained an average effect size of meditation on concentration of 0.39 SD, a lower number than reported in the two meta-analyses I cited earlier but still sizeable. The average meditator has better control over her attention than 65% of the general public.
Kabat-Zinn’s concept on nonjudgmental attention can be applied to more standard tasks of attention as well. Often, we look with an agenda, or we close off our minds prematurely. I would venture that paying attention in an open, nonreactive way would be an excellent example of this nonjudgmental stance.
One task that has been used to test the hypothesis that meditation experience might lead to a more objective, open-minded, nonjudgmental type of attention is the attentional blink task. In this task, you see a stream of about 20 or so letters, spit out one right after another on a computer screen at an impossible pace—typically 1/10 of a second for each of them. One or two digits are intermingled with the letters, and you simply press a button whenever you spot a digit. It turns out that when the stream contains two digits, people often miss the second digit when it is shown less than half a second after the first one. It is as if seeing the first digit causes you to mentally blink—hence the name of the task.
The standard explanation for the attentional blink effect is that you need to focus really hard to detect any digit to begin with. If you devote a lot of attention to detecting the first digit, you have no resources left for the second. To put this in terms of mindfulness: What makes you miss the second digit is that you are “stuck” on the first digit—too much investment, too much eagerness, too much “attachment” to doing it right (that is the judgmental mind, right there) and not missing that first digit. Unexpected confirmation for this account comes from studies where people are asked to do the task while they are being distracted by listening to music or viewing pictures—they do better when distracted than when they apply their full attention to finding the digits.11
Three studies have looked at attentional blink and meditation.12 Two compared long-term practitioners with novices. They indeed found smaller attentional blink effects in meditators; the average effect size was 0.65 SD; the average meditator was less susceptible to attentional blink than 74% of nonmeditators. One of these two studies also compared attentional blink before and after a three-month retreat; the effect size, comparing attentional blink before the retreat with attentional blink after the retreat, was 0.38 SD in beginning meditators and 1.17 SD in advanced meditators.
If it is true that this decrease in attentional blink has to do with openness and nonreactivity, then you might expect that open-monitoring meditation, with its wider horizons, would lead to less attentional blink than focused-attention meditation, with its more narrow focus. Marieke van Vugt and Heleen Slagter13 tested this with a group of 30 long-term practitioners of Zen, Tibetan Buddhism, or Vipassanā. They asked these participants to do the attention blink task while they were meditating in either a focused-attention or open-monitoring style (all participants were intimately familiar with both styles). They found that in the group of participants with the largest amount of experience (more than 2,600 hours), the attentional blink effect was indeed smaller during open-monitoring meditation, suggesting a less sticky quality to their attention. In the group with less experience (still on average 1,377 hours), however, there was no difference. This suggests that meditators can fine-tune the amount of nonreactive attention they bring to a task, but it also suggests that this ability takes some time to develop.
Other studies and tasks further show that meditators may have learned to pay attention in a more open, nonreactive way. For instance, one study14 showed people the infamous gorilla video (if you have ever taken a Psychology 101 class, you’ve seen it—two group of students are playing basketball, you are asked to count the number of passes in one of the two groups, ignoring the other, and in the middle of the game, a man in a gorilla suit walks through the group of players; about two-thirds of people typically fail to see the gorilla). They found that meditators were 50% more likely to spot the gorilla than nonmeditators. They were also about twice as accurate in keeping count of the passes, suggesting that they were able to be focused and open-minded at the same time.
Another study15 used a startle-type task (you may remember we saw one particularly compelling study of startle in one Tibetan monk in Chapter 3). You stand in front of a screen. At one point, a light turns on either to the left or the right; your task is to turn your head toward the light as fast as you can. Intriguingly, you will be faster at doing this when a blast of sound (coming from the center) is delivered at the same time as the light—one of the few examples where a distracting event can actually make you faster. The likely explanation is that the loud noise—if you let it get to you—gives you some extra boost of mental oomph. It turns out that meditators are less likely to speed up than nonmeditators. This suggests that meditators are able to just process the sound, without attaching a startling quality to it—it is just a loud noise.
A third study that demonstrates that meditators may have lower reactivity is one study on the Stroop effect we’ve already encountered in the previous section.16 In this study, the researchers also recorded brainwaves. They were particularly interested in two types of waveforms. The first is the so-called error-related negativity (ERN; “negativity” here has nothing to do with anything bad—it’s just that the electrical polarity of the brain signal is negative). The ERN typically happens right after you make an incorrect response (to be precise, about 1/10 of a second after). The signal likely comes from the anterior cingulate cortex, a part of the salience attention system, as we have seen. The ERN signifies that your brain has spotted that you have made a mistake—it is the brain going “oops.” However, the presence of an ERN wave doesn’t always mean that “you” will spot the mistake—even if you produce an ERN, you are not always aware that you just made an error. The awareness of making an error (your “Oh no!” response) is related to a second type of wave, the error-related positivity effect (confusingly abbreviated as Pe; again, positive here simply refers to the polarity of the brain signal). The Pe occurs a little later than the ERN, about 2/10 of a second after making an error, and it is thought to originate in the posterior cingulate, which is, as we have seen, part of the core of the default-mode network (the part that seems to get turned down during meditation). The researchers found that the ERN effect is larger in meditators than in nonmeditators and that years and frequency of meditation correlated with ERN as well (the correlation was .37 and .35, respectively), showing that meditators’ brains are more alert to the mistakes they make. Interestingly, meditators did not show larger Pe values—thus their increased sensitivity to errors does not lead to stronger awareness of errors. That is, even though a meditator’s brain quickly realizes and reacts to its mistakes, it is also very quick to let go of that reaction.
In a fourth study, Sara van Leeuwen and colleagues17 showed people local-global stimuli, one at a time. A local-global stimulus is a large digit formed out of multiple identical small digits (e.g., a large 3 made up of tiny 8s). They asked their participants to press a button when they saw the digit 1 or 2, regardless of whether it was the global (large) or local (small) digit in the figure. Typically, people process the big, glaring global digit first, and so they are typically faster to report the 1 or 2 if it is a global digit than a local digit—in this study the difference was 56 milliseconds.18 The study also included eight Buddhist monks and nuns; they showed less of a bias toward the global digit—for them the difference was only 21 milliseconds. This suggests that the monastics had more openness to what is really there, namely two different digits. Brainwaves were also examined, and it turned out that the meditators’ brains showed stronger responses in the very early stages of processing, within the first 150 milliseconds or so,19 suggesting a quicker uptake of information; they also showed larger engagement in the attention networks that are typically implicated in this task.20
We end this section with a small anecdotal finding from one study, done by Elizabeth Valentine and Philip Sweet.21 They had people listen to 60 series of 2 to 11 bleeps; all they had to do was count the number of bleeps. The researchers note that many participants in the control group—the nonmeditators—commented on how boring this task was; none of the meditators did. This may, of course, simply mean that meditators are more polite or shyer to speak up than nonmeditators, but it may also mean that meditators meet their experiences with a different attitude, maybe with added openness. This, I find, is an interesting potential side effect of meditation worthy of further exploration: less boredom in daily life!
Let me note that another way of examining changes in this nonjudgmental attitude would be to give meditators and nonmeditators surveys that measure trait mindfulness. This has been done, and I report those findings in the next chapter, because they fit better in an overview of the subjective well-being side of things than in the objective tests of attention discussed in this chapter.
Meditation manuals often imply that meditation will give you a more objective, accurate, and efficient way of looking at the world, maybe as a consequence of cultivating a nonreactive, nonjudgmental alerting mode of dealing with distractions in meditation. There are some reports that suggest that this may be the case.
One is the van Leeuwen local-global study I mentioned in the previous section. Another example is a study by Christian Jensen and colleagues.22 They had people perform attention tasks before and after a standard eight-week MBSR training. In one of those tasks people read out letters that were flashed very briefly on a computer screen. By varying the duration each letter was flashed, the researchers were able to calculate how much time each participant needed to identify a single letter. Before training, it took participants 15 milliseconds to identify a letter; after MBSR, this was reduced to 9 milliseconds. Different control groups were included as well; neither of these improved in the speed of letter reading.
Likewise, Katherine MacLean and colleagues23 tested seasoned meditators before, during, and after a three-month retreat and compared their performance with that of a no-retreat control group of equally seasoned meditators. The participants were shown two lines of different length, one after the other, and were asked to say which line was longest. The difference in length between the lines was varied so that the researchers could determine the minimum difference in line length that people are able to detect. Retreatants and nonretreatants did not differ in this minimum difference before the retreat, but retreatants were able to detect smaller differences between the lines both at the halfway point of the retreat and at the end of the retreat, as well at a follow-up session five months after the end of the retreat. There was a dose–response relationship: Those who spent more time in daily meditation during the after-retreat period could detect smaller differences between the two lines (r = .36).
These three studies, then, suggest that meditators have a faster and more precise uptake of what is out there in the world.
The third aspect of attention that is likely trained in meditation is the ability to sustain and stabilize your awareness on what it should be focused on. Psychologists typically gauge sustained attention by giving their participants very simple tasks. We could ask you, for instance, to look at letters passing by and press a button whenever the letter “k” appears. This is an easy task. The twist is that we make you do this for a very long time—typically 10 to 30 minutes in one go. This makes your time in the lab mind-numbingly boring. What is measured is how well you do at the end of the task, when you are terminally bored, tired, or both, compared to the beginning, when your mind was bright and fresh. Another way of measuring stability of attention is to stop you from time to time during these boring tasks and simply ask you if you were on task or not.
Maybe surprisingly, there is not a lot of research on meditation and sustained attention. I was able to locate seven studies.24 Those yielded an average effect of 0.39 SD, on par with that for attention control and less than that for nonjudgmental alerting. Five of these studies used novices going through MBSR or an MBSR-like program; the average effect size was 0.33 SD. Two studies compared seasoned meditators before and after a three-month retreat (where the participants meditated for about 500 hours). They showed an average effect size of 0.60 SD, suggesting that an intense period of practice leads to a better ability to sustain attention. As far as I can tell, only one of the studies looked for a dose–response relationship; it did not find one.
Here I single out one additional study, done by Olivia Carter and colleagues, that used two rather exceptional tasks to measure stability of attention.25 This study was exceptional for another reason as well: The research team traveled all the way to the Himalayan mountains in Ladakh, a region in northern India, to test Tibetan Buddhist monks living in exile there.
The first task they used was a binocular rivalry task. Binocular rivalry refers to a very curious sensation that happens when each of your eyes sees a different picture (e.g., your right eye sees a house, your left eye sees a face; to do this you can either use virtual reality goggles or, cheaper, red/green 3-D glasses26). You might expect that you would see a composite image—the face overlaid on the house, or vice versa—but that is not the case. Instead, what happens is that your awareness keeps switching between the two—now you see the face, then the house, then the face again, and so on. The two images tend to alternate every few seconds, with a brief period in between where you can feel the two images wrestle for dominance.
Why travel all the way to a remote region in India to show these images to monks? Well, attention appears to have an influence on the frequency of alterations: If you focus really hard on one image, you can keep it active in awareness a little longer. Carter et al. showed 23 monks binocular stimuli while they were meditating in one of two modes: focused-attention meditation or compassion meditation. Compassion meditation did not lead to any changes, as you might expect (the primary focus in this type of meditation is not on an outside object). Focused-attention meditation, however, did lead to slower alterations (i.e., more stability) in over half of the monks, both during and after the meditation.27
The second task Carter et al. included in this study was a motion-induced blindness task.28 Motion-induced blindness is a visual illusion. You stare at a blinking green dot at the center of a computer screen that also has three yellow dots arranged in a triangle closer to the edge of the screen and a lattice of crosses that rotates. If you look intently enough, the yellow dots disappear after about 10 seconds (sometimes all three of them at the same time, sometimes just one or two). As soon as you relax your attention or move your eyes, the three dots reappear. The average student volunteer is able to keep the three dots from reappearing for 2.6 seconds. The average monk was able to do this for 4.1 seconds, or about 50% longer. More important, the duration record in the group of students was 6 seconds; 10 of 76 monks tested equaled or beat that record—one monk was able to stabilize the image for 128 seconds, and one even for 723 seconds. (This study also illustrates that the sustained attention effects that we have looked at so far, even in advanced meditators, are peanuts compared to the feats that true meditation experts are able to deliver.)29
Attention—as you know—fluctuates. A slight cold or a bad night’s sleep and it becomes hard to focus; nothing like a cup of coffee to perk you up. One psychological variable that influences attention is effort. (Psychologists call this “motivation to perform.”) When you apply more effort to a task, you typically do better; when you make only a half-hearted effort, you’ll likely not to do as well as you possibly could.
Some have criticized the studies on meditation/mindfulness and attention on this ground: It is possible that what changes is not attention per se but the amount of effort that people are willing to put into the task. Remember the Valentine and Sweet study, with the boring bleep counting task? In that study, nonmeditators remarked on how tedious the task was; meditators did not complain. It is then possible that meditators did better on the task not because their core capacity for attention increased but simply because their attitude changed. Maybe they were more motivated and thus more willing to invest effort.
One study, by Christian Jensen and colleagues,30 tried to tease those two explanations apart. They compared participants in an MBSR program with a group of people who underwent a non-mindfulness–based stress reduction program and also with two groups of people who did not go through a stress reduction program at all. One of the latter groups was simply tested twice; the second group was offered $50 if they did better on the second test than the first test. For our purposes, it is the comparison with the latter group that is interesting—they had a clear incentive to apply more effort. (I can’t speak for you, but I’d happily take $50 to do my very best on an hour’s worth of attention tests!)
The researchers found that the MBSR group did better on tests of focused attention and on a visual threshold task than any other group. In contrast, they did as well as or worse than the $50 group on tasks that measured how well they could switch attention, return to the present moment, or be ready to react. This suggests that meditation may have an effect on focused attention and on visual perception that is not due to just effort. Effects on attention switching and on alertness are, however, suspect. Maybe MBSR-trained participants are more willing to invest the effort, perhaps because they want to prove the value of the treatment to themselves and/or the researchers.
One conclusion is that some of the effects of mindfulness and meditation on attention may be due to changes in effort, or the willingness to invest effort, rather than to changes in attention per se. You could also, of course, wonder if this distinction is truly important in day-to-day life: A change in your underlying attitude to life, especially an increased willingness to meet challenges with a bit more energy, seems like a vital part of healthy daily functioning to me. This, of course, would assume that meditators approach life in general with rejuvenated vim, and not just life inside the researchers’ lab.
In many mindfulness traditions, paying attention to certain aspects of the body—the breath, the fleeting sensations that arise during a body scan, the sensations of how emotions actually inscribe themselves in the body—is a central aspect of the training. Given this central place of body awareness in mindfulness training, you would expect quite a number of studies on this topic. This is not the case, however. There aren’t enough studies (for most of the topics falling under this heading) to warrant a meta-analysis, so I just briefly describe each of the studies and see if I can draw any meaningful conclusions.
First, the breath.
The one study that I was able to find31 used two metrics. Participants were hooked up to a machine that registered their breathing—their nose was clipped shut, and they breathed into a mouthpiece that measured airflow. In a first task, the researchers added resistance to the air flow by placing little discs in the tube; they checked whether participants could tell whether or not the airflow was restricted. The answer is that people are quite accurate in this task, and meditators not more so than nonmeditators. In a second task, participants used a slider to indicate the frequency and depth of their breathing as they were hooked up to this machine. Meditators turned out to be a bit more accurate in matching the slider to their actual breathing. This, however, turned out not to be a meaningful difference. That is, meditators are also (as we have seen in Chapter 2) typically slower in their breathing, and this was true in this study as well. It is easier to detect and match slow breathing than fast breathing. When the researchers took this effect into account, meditators were no better at following their breath than nonmeditators. Note, of course, that the breath is typically easy to detect—this is actually one of the reasons it is so often used as the point of focus for beginners—so there isn’t necessarily a lot of room for improvement after meditation.
The same cannot be said about heart rate: Those of you who wear fitness bands or smart watches with heart rate monitors know that heart rate is quite a bit harder to predict than breathing. Two studies32 failed to show that meditators were better at heart rate detection than nonmeditators.
Two studies have looked at sensitivity to touch.33 Kieran Fox and colleagues asked meditators and nonmeditators to indicate how sensitive each of 20 body regions (each of the fingers, the palm of the hand, the lips, the cheek, the nose, etc.) were; they correlated those ratings with what previous research has told us about these regions’ sensitivity.34 Nonmeditators showed correlations that were zero or negative, indicating that they cannot identify the relative sensitivity of parts of the human body. In contrast, meditators produced correlations between .31 and .46 (depending on the index of true sensibility), showing that they do know what areas of the human body are more or less sensitive. Accuracy (as measured by these correlations) also went up with the total number of hours spent in meditation (the correlation between accuracy and the logarithm of total number of hours of practice varied between .37 and .48, depending on the index of true sensibility); this increases the possibility that the increased sensitivity is due to meditation itself. Moreover, people who practiced body scan meditation did better (correlations between .41 and .64) than people who were novices in this particular technique (correlations between .06 and .18), suggesting that it is indeed paying attention to the body that drives this form of body awareness.
Laura Mirams looked more objectively at touch detection. A little vibrator was strapped to the participant’s index finger; his job was to indicate when the vibrator vibrated. The vibrations were set such that they were barely detectable; on some trials, a light was also flashed near the finger, with or without vibration. In that case, people often mistakenly reported vibration when the only thing happening was that the light flashed. Students who had gone through a short (two-hour) body scan meditation program made fewer mistakes than before they were meditating and made fewer mistakes than nonmeditators. They also detected the real vibrations more easily. Thus even a very short meditation program can have some effect on touch sensitivity.
Meditation may also lead to better coordination between seeing and acting. José Raúl Naranjo and Stefan Schmidt35 asked their participants to trace a line between two dots on a tablet. Participants couldn’t see the actual tablet but were given visual feedback on a projection screen. Unbeknownst to them, the visual feedback was not completely correct, and so the angle of the line they were seeing was off. Three groups were included: long-term meditators (with, on average, 22 years of practice); a group of short-term meditators, tested before and after an MBSR program; and a control group of nonmeditators. The researchers found that long-term meditators were more accurate in line tracing, mostly because they slowed down, which made them able to be more deliberate in their movements. The MBSR participants were fast before the program and slowed down afterwards, resulting in higher tracing accuracy. The control group showed no changes. Thus mindfulness training seems to help people to control their actions better, and maybe even to select the best way of doing so, but doesn’t necessarily really have an effect on the coordination between seeing and doing.
One study examined self-reported body awareness in daily life. In this study,36 152 participants in a three-month mindfulness program reported on eight different aspects of their so-called interoceptive awareness—the awareness of what is happening inside the body, often—in this case—with an emotional tinge. The researchers found that the answers of mindfulness-trained participants changed more than those of control participants for five of the eight aspects: Self-regulation (e.g., “When I feel overwhelmed I can find a calm place inside”); attention regulation (e.g., “I can refocus my attention from thinking to sensing my body”); body listening (e.g., “I listen for information from my body about my emotional state”); body trusting (e.g., “I feel my body is a safe place”); and emotional awareness (e.g., “I notice how my body changes when I am angry”). Aspects that didn’t change were not-distracting (i.e., saying no to “I distract myself from sensations of discomfort”); not-worrying (i.e., saying no to “I start to worry that something is wrong if I feel any discomfort”); and noticing (“I notice changes in my breathing, such as whether it slows down or speeds up”). The average effect size, across the eight aspects, was 0.31 SD. Attention-regulation and self-regulation showed a dose–response relationship (the correlations between these aspects and total number of hours practiced were .18 and .22). Interestingly, the researchers found correlations between scores on the five aspects of body awareness that changed over practice and responses to questions that probed for how much the participants enjoyed the practice and looked forward to it—the more people enjoyed mindfulness exercises, the better they became attuned to their bodies, or vice versa (the correlations ranged from .30 to .43).
One reason this study shows a connection between body awareness and awareness of emotion might be an increased integration between body awareness and emotional awareness. Jocelyn Sze and her colleagues37 monitored the heart rate of three groups of participants (meditators, dancers, and nonmeditators who also didn’t dance) while they were watching a series of short emotional clips (depicting such things as a woman reacting to the news that her family members have died, a man chewing cow intestines, or a funny improv). The participants turned a dial to indicate their level of emotion (between negative and positive). The meditators showed the largest correlation between their heart-rate data (a good measure of physiological arousal) and their emotion ratings, followed by the dancers, who in turn did better than the nondancing nonmeditators. Thus meditators seem to be particularly good at tapping into the physiological markers of their emotions.38
Finally, the most researched aspect of the effects of mindfulness on paying attention to the body—this may surprise you—is increased sensitivity to signs of sexual arousal. The context here is the treatment of a specific type of sexual dysfunction in women, sometimes called “wanting to want”—having a lower sex drive than desired. Sexual arousal is an interplay between physiology and psychological factors—there is the bodily feeling of desire and the emotional oomph that (hopefully) accompanies it. It turns out that some women have difficulty connecting the two: While their bodies show signs of sexual arousal, their minds do not register the changes, and they remain emotionally unstirred.39 Some have proposed that mindfulness could be very useful here, as it helps you to tune into your body. Additionally, mindfulness training stresses the suspension of judgment, which can be helpful as well—many women with sexual difficulties report that they associate sexual acts with concerns over performance, body image concerns, and/or partner and relationship issues, none of which are particularly helpful thoughts to have in that context.40
Most of the work in this area was done by Lori Brotto and colleagues.41 The participants were women who were seeking treatment for sexual difficulties. The interventions in these studies typically consist of a two-week or four-week program combining mindfulness exercises (such as following the breath and a body scan) with education about diverse aspects of female sexuality (e.g., discussion of the female response cycle, discussion about the importance of sexuality in the participants’ lives, and/or discussion of psychological influences on sexual behavior). The researchers measured how good participants were at judging their level of arousal, how much their ratings of arousal corresponded to physiological measures, or how they rated themselves on scales for sexual desire, sexual arousal, lubrication, sexual satisfaction, and overall sexual functioning. Average effect size for the three studies that included a control group was 0.63 SD.
All these interventions contain multiple components. How can we conclude with certainty that the mindfulness component was the crucial part of the mix?
One study42 can help here. Brotto and colleagues compared a two-week mindfulness-based intervention (with an education component) to a two-week cognitive-based therapy intervention (with the same education component). They measured vaginal pulse amplitude (an objective, physiological measure of sexual arousal) while participants were watching an erotic movie; participants also used a computer mouse to indicate, moment to moment, their feelings of sexual arousal. The researchers found that mindfulness-trained participants became better at tracking their physiological arousal over time—mindfulness had helped them tune in to their body sensations. This was not the case in the cognitive-based therapy group. Unfortunately, this study included an extremely small sample—8 women in the mindfulness group and 12 in the cognitive-based therapy group—so the results can only be taken as suggestive, rather than definitive; they are nevertheless encouraging.
There are a few additional results that are noteworthy. First, at least two studies43 found that mindfulness treatment in women (many of them suffering from low sexual desire, from failure to become aroused or to reach orgasm, or from pain during intercourse) led to higher levels of sexual and emotional intimacy, better communication with their partner, and more satisfaction with the relationship.
There is also some evidence that mindfulness treatment may be especially beneficial for women who have survived sexual abuse, maybe because it turns their attention inward, facing their own momentary sensations as they occur, rather than asking them to engage with their past, traumatic experience.44
Finally, one study45 found a relationship between changes in trait mindfulness (as measured by the Five-Facet Mindfulness Questionnaire) from before to after a meditation program and changes in how quickly participants were able to judge their level of sexual arousal for erotic pictures (the correlation was .44—people who were more mindful were faster judges). Likewise, changes in self-reported anxiety correlated with changes in speed of judgments (correlation of .59—more relaxed participants were faster judges). This gives us a glimpse at the potential mechanism: Meditation makes you both more relaxed and more mindful, and this allows for more openness to erotic stimulation. It is quite possible then that this is simply another example of mindfulness practice creating a more open, nonjudgmental mind.
An interesting often-noted side effect of mindfulness practice is a change in the practitioner’s relationship to time—the present moment expands, and time seems to slow down. Why would that be?
One reason might be that your sense of time is related to how much attention you are paying to what is happening. This is true both for timekeeping (i.e., keeping track of time as it is unfolding now; e.g., I am brewing tea, and I need to let it steep for three minutes) and for looking back in time (e.g., how many hours did we spend on the beach yesterday?).
The best theory we have for how internal timekeeping works (at least for short durations) is that we have an internal clock. This clock has two parts: a pacemaker (the easiest metaphor is to image something that ticks, like, indeed, a clock) and an accumulator (e.g., a counter that keep track of how many ticks have been emitted)46. Two things influence this clock. The first is physiological arousal: When you are in a more relaxed state, the ticking goes slower. The second is attention: When your attention is focused on keeping time, you are more likely to collect all the ticks in the accumulator; when you are distracted or absorbed in something else, you might miss a few (or even a lot of) ticks. So if you are distracted, your accumulator will fill up more slowly; this means that the experience will be a little more timeless—time will run more slowly, which will make it seem as if it passes by more quickly. (In my own tea-making experience: If I pour the water and then lose myself in email, I will end up with a bitter brew.)47 To quote Herbert Woodrow48: “Situations especially favorable to an experience that is subjectively timeless are those characterized by intensely absorbing occupations, such as reading an interesting novel, contemplating the beautiful hallucinations produced by some drugs, or battling for one’s life.”
Does meditation fit Woodrow’s list? Two studies to date have compared timekeeping between meditators and nonmeditators49; one of those50 found that meditators indeed underestimated time durations (i.e., meditators asked to press a button when they thought that, say, 8 seconds had passed were more likely to press the button after 10 seconds or so, indicating that the perception of time had slowed down); the other study,51 however, did not. Two other studies looked at timekeeping right after a guided meditation of a few minutes; one52 found that this slowed down time perception and the other53 that it only did so in experienced meditators. The conclusion is that the evidence for a slowing down of time perception due to mindfulness practice leans ever so slightly in the direction that it might.
What about estimating time duration in the past?
The best theory we have for how we look back at time is based on memory: When you look back on an event or a time period (yesterday or last week), you retrieve memories from the event or the time period. If a lot of things happened to you during the event or time period, you are more likely to come up with more memories. If you come up with more memories, you will perceive the event as having lasted longer—filled to the brim. (For instance, if you spent yesterday afternoon at the beach soaking up the sun, you will estimate the duration as shorter than if you spent it playing beach volleyball, swimming, and running back and forth to the ice cream truck.)
There are (as far as I can tell) only two studies that have investigated how meditators look back at experiences. One study54 had nonmeditators and participants in a mindfulness program watch a five-minute nature video clip while they were waiting for the experiment to begin; the experiment itself consisted of asking them how long they thought the video clip was. If they were more engaged with the video, or with their inner experience, they would experience more “events,” and time would seem longer in retrospect. The meditators indeed thought the video clip was longer (4.14 minutes) than the nonmeditators (3.29 minutes). Essentially the same result was found (4.26 minutes vs. 3.73 minutes) when people were just left in the waiting room with no distractions and asked how long they thought they had been waiting, probably because meditators create more “events” by paying attention to their inner state and/or the outer world. Another study55 used simple questionnaires to look at judgments of time. The researchers found that meditators felt less time pressure than nonmeditators (measured through answers on questions such as “I often think that time is running out”) and had a more spacious sense of time (measured by questions such as “My time is filled”). The past week and the past month also went by more slowly for meditators than for nonmeditators. (There were no differences in the experience of the past year.)
These two studies, then, suggest that time gets filled more for meditators than for nonmeditators, regardless of what kind of external events fill the time. Another way of putting this is saying that, again, one of the side effects of a meditation practice may be less boredom.
It appears, then, that meditation sharpens and tunes attention across a wide variety of tasks and situations. Does it have an effect on other aspects of cognitive functioning as well? The short answer is that we still know very little about this.
Five studies56 have looked at what psychologists call working memory. Working memory is the kind of back-of-the-mind memory that operates for a brief period of time—a few seconds. An example is you are having a conversation with a friend and something she says reminds you of something you want to say. While you wait your turn and focus on what you are supposed to be doing (listening to your friend), you stash away what you want to say in the back of your mind: That is working memory. Four out of the five meditation studies on working memory used beginners; all used relatively short interventions (on average 18 hours of meditation). The average effect over the five studies was 0.32 SD; the average meditator has a better working memory than 62% of nonmeditators.
The only other cognitive task that has more than a single study dedicated to it is verbal fluency. In a verbal fluency task, you are asked to come up with as many, say, animals or words starting with the letter S you can think of in the span of a few minutes. This may look like a straight-up test for your vocabulary, but it really is also a test of how smartly you can apply your attention. Take the “name as many animals as you can” example. Most people start off strong, rattling off all animals they can think of within a category (maybe pets); when they feel that category is exhausted, they typically move over to another category (maybe farm animals), and when that category is exhausted, they move to another one (maybe zoo animals), and so on. One trick to do well on this test is to jump to the next category as soon as the one you are working on runs dry; another trick is to figure out when that happens. Sometimes people get stuck trying to squeeze as many animals as they can out of a particular category and start repeating themselves, going over the same names again and again. The two studies57 that have looked at the effect of mindfulness training on verbal fluency have found positive effect sizes—1.43 SD and 0.28 SD, respectively.
Finally, one study58 found an effect size of 0.32 SD on the verbal GRE.
Given that meditation and mindfulness have what appear to be moderate effects on attention, it makes sense to ask if mindfulness interventions could be of use for people who show specific impairments in this domain. Mindfulness has indeed recently (the earliest published study dates from 2008) been used as a therapy for individuals with attention deficit hyperactivity disorder (ADHD). ADHD is a developmental condition, often continuing into adulthood, that affects about 3% to 5% of people in the United States and is characterized by frequent bouts of inattention (e.g., difficulty concentrating, difficulty sustaining attention, difficulty listening, being easily distracted), impulsivity (e.g., butting into conversations, difficulty awaiting one’s turn, emotional outbursts), and hyperactivity (e.g., fidgeting, feelings of restlessness, running about, excessive talking).
There are no meta-analyses on the effects of mindfulness on ADHD,59 but there is one overview article by John Mitchell and colleagues.60 They were able to locate three studies on ADHD and mindfulness training in children and adolescents, five more in which children and adolescents participated with their parents, and nine studies on adults with ADHD—a modest harvest.61 In total (and only counting people who went through treatment, not the control subjects), 294 individuals with ADHD were trained and tested, or an average of 17 per study (varying from 1 to 72). Eight of the studies included a control group; seven did not.
Most studies in this field are then what are considered to be “pilot studies,” that is, studies that are done to quickly check if it makes sense to conduct a full-scale clinical study. (They are pilots in the old sense of the word: guides.) The goal of a pilot study is to see if the intervention is indeed successful (e.g., does it show an effect?) and also—equally important in early stages of clinical research—if the study can actually be done (do people like the intervention, or do they drop out? do people follow the instructions well? can the trainers handle what is thrown at them?).
The typical intervention in mindfulness-for-ADHD studies is about 8 to 10 weeks long. Many of these involve adaptations of existing curricula, like MBCT or DBT, but there are also programs specifically designed for treating ADHD with mindfulness principles: MYmind, aimed at children and adolescents and their parents,62 and Mindfulness Awareness Practices for adults.63 These programs combine education about ADHD with mindfulness exercises and practices. This, of course, makes it hard to gauge what the ingredients for success (if any) actually are.
A first conclusion from these studies is that mindfulness is a feasible intervention for ADHD—it can be done. Studies that note the participants’ reactions mention that they find the intervention enjoyable, and the number of participants who follow the program all the way through is high—around 80% in the studies that report the numbers. This is encouraging indeed, because it is far from self-evident that people who generally have a short attention span and are quite distractible would enjoy the stillness of mindfulness activities enough to continue a demanding program for two or three months.
A second conclusion is that the studies show moderate support for the position that mindfulness is helpful to individuals with ADHD.
Let’s first look at changes in self-report, that is, how individuals with ADHD describe their symptoms and experiences. In four out of five relevant studies, participants indicated lower levels of inattention after the intervention compared to before; in three out of three, they indicated lower levels of hyperactivity; in three out of four, the total number of ADHD symptoms declined; in three out of five, they indicated lower levels of depression; in one out of two, lower levels of anxiety were noted; in one out of two, the participants reported a lower incidence of “externalizing behavior” (i.e., acting out); and in three out of five, they noted an increase in quality of life. The score sheet is far from perfect, but these are, indeed, nice results.
Some studies also looked at other-reports, that is, assessment by parents, teachers, clinicians, or peers. The evidence is a bit more mixed in this case: One out of two studies noticed less inattention; two out of three lower levels of hyperactivity; and one out of two lower levels of depression.
Finally, scores on actual attention tests show an equally mixed picture. Studies including multiple types of measures often only obtained changes in a few (or none) of these (in two cases four out of 12, in another case one out of three, in yet another case one out of two; and there are three studies with null results: zero out of four, zero out of three, and zero out of one). Taken together, that means that across studies, we find six significant results out of 25 possible—a 24% hit rate. Clearly, this is not a slam-dunk.
One study64 examined brainwaves. After the intervention, the researchers found an increase in error-related positivity in a go/no-go task, suggesting heightened awareness of errors. Changes in error-related positivity correlated with a decrease in hyperactivity/impulsivity symptoms and increased trait mindfulness. There was also an increase in a specific brainwave component (the P3) that is related to how strongly you engage attention; changes in P3 correlated with a decrease in inattention symptoms. Thus the intervention was associated with brain markers of attention during an attention task, and these changes also translated into an improvement of symptoms.
A final question concerns the duration of these effects. The results for adolescents and children are mixed—three studies65 conducted follow-up at eight weeks; five out of eight measures that were found significant right after the intervention were also significant at follow-up. Encouragingly, what seemed preserved was mostly the gain on ADHD core symptoms. For adults, in all three studies66 that included follow-up (at three months or six months), the gains that were found at the end of the intervention were still there at follow-up.
Taken together, these results seem promising. They suggest that mindfulness training can help ease the burden of the core symptoms of ADHD in a number of people. The results on objective tests are less clear-cut. All this work is still in the pilot stage. We need larger scale clinical studies with control groups to reach firmer conclusions; these would also help us get a good idea of the size of the effect.
Meditation has an effect on all three forms of attention I have reviewed here: Its effect on focused attention is around 0.4 SD; a similar effect is noted on sustained attention; and there are also consistent effects on nonjudgmental alerting, with an effect size of 0.65 SD for attentional blink studies.67 Meditators, especially those who practice body scan meditation, seem to have a keener sense of the body in terms of touch, better coordination between seeing and acting, and heightened body awareness in daily life; they are not better at detecting the breath or the heartbeat. Also, their sense of time expands.
I was particularly intrigued by the many studies that found evidence for nonjudgmental alerting, arguably the core aspect of Kabat-Zinn’s definition of mindfulness—we see it in the attentional blink task, the gorilla video task, the (non) startle effect, the local-global effect, and in brain parameters like error-related negativity and positivity. Having so much converging evidence from so many different types of tasks is heartening. It is also interesting because this is an aspect of attention that is somewhat undervalued in standard cognitive psychology, where we are more interested in the amount or acuity of attention (how much can we take in, and how sharp do we see it?), rather than its quality. We often think of open-mindedness as something complex, an ability that operates at a high level of the mind (here I am, all open-minded!) and not as something that operates in a process as basic as paying attention and as a skill that can be trained. Two studies even suggest that meditation practice can help lower the threshold of perception, literally letting more of the outside world enter the realm of awareness. An interesting side note in this respect is the finding—in two different contexts—that meditation experience seems to make life a little less boring.
Attention is often considered the gateway to other aspects of cognition. Particularly, attention is important for working memory, helps with knowledge retrieval, and is important for real-life aspects of cognition (for which we saw only one example—GRE scores). All of these aspects of cognition indeed seem to benefit from meditation and mindfulness training, although the number of studies and the number of participants involved in each of these studies is still too small to allow for definitive conclusions.
Many studies underscore the importance of frequency or amount of meditation, rather than accumulated hours of practice. Frequent practice appears to sharpen the focus of attention, to alert you to mistakes, to broaden the limits of perception, and to help sustain attention. And, of course, the finding that eight-week MBSR programs can have a meaningful impact on attention, often on par with the effects seen in very seasoned meditators, underscores this point.
Finally, the attention-enhancing properties of meditation have led to promising clinical applications. There is early, encouraging but far from definitive evidence that mindfulness training might be helpful in easing the symptom burden of ADHD and quite good evidence that it may be beneficial for sexual dysfunctions that have their root in a lack of awareness of the physiological signs of arousal.
There are many open questions still.
First, one study investigated the role of attentional effort, arguing that what we are seeing in mindfulness-trained people is not the effect of the training per se but a newfound willingness to go the extra mile. That is a very good point, and it deserves further scrutiny.
Second, it would be great to know if there is an order to these effects—does one type of attention develop earlier than the other? Some68 have claimed that changes in focused attention would come first and changes in sustained attention later, but I did not see much evidence for this position in the literature. The simple answer is that we don’t know. We need an intervention study that looks at all three aspects of attention (and probably a few more cognitive and well-being type measures as well) and measures the effects repeatedly over the course of the training program.
A third open question is how these changes relate to changes in brain activation, and especially to changes in brain morphology—the link, so to speak, with the two previous chapters.