[Edit 2025-11-29: I wrote this post when I was very new to meditation, long before experiencing stream entry.]

Proponents of meditation claim it causes long-term beneficial changes to a person's mind. Does it? Altered Traits: Science Reveals How Meditation Changes Your Mind, Brain, and Body by science journalist Daniel Goleman and neuroscientist Richard (Richie) Davidson attempts to answer this question using the newest research.

The book has three main themes.

It starts by establishing what constitutes rigorous research.
The bulk of the book is dedicated to asking "Does meditation make you a better person?" where "better" can mean "healthier", "more capable" or "more altruistic". This section is focused on ordinary practitioners.
The book ends with a yogi in a brain scanner.

Obstacles to Research

The United States government suppresses research into mind-altering drugs under penalty of imprisonment. Research into mind-altering contemplative practices got caught in the crossfire. For this and other reasons ^[[1]] , there has been little research into meditation in the Western world until very recently. Much of what we do have is shoddy.

Meditation is hard to study scientifically for all the reasons it's hard to study sleep plus all the reasons it's hard to study weightlifting.

Sleep is hard to study because it happens invisibly inside a person's head and if you ask them what's going on they wake up and the altered state of consciousness disappears.
Weightlifting is hard to study because weightlifting involves hard work applied over a long time with proper technique. Optimal training for a beginner is different from optimal training for an athlete. Optimal training for an athlete depends on the sport an athlete is training for. Even if you could handwave away liability concerns, it's hard to pay volunteers to participate in a 20-year-long weightlifting program. Weightlifting is impossible to double-blind. (I'm going to ignore how many weightlifters take drugs while pretending not to.)

Due to the dearth of research, it is plausible Western science has left low-hanging fruit unpicked. If LSD can cure PTSD and MDMA can help autistic people socialize then it's conceivable meditation might cultivate altered traits too.

The Frontiers of Science

The first several chapters of Altered Traits explain the challenges associated with studying meditation scientifically and how scientists can deal with them. They discuss discriminant validity and active control groups ad nauseum. These chapters are as boring as they are rigorous. The payoff begins in Chapter 6.

Positive Effects

Compassion

Many of the studies in this book revolve around lovingkindness meditation which cultivates compassion. The first thing the authors do is confirm that a compassionate attitude actually increases altruistic behavior. It does ^[[2]] . Compassion increases joy and happiness too. Having established compassion ⇒ altruism, they can investigate whether meditation produces longterm increases in compassion. (It is trivially easy to show that lovingkindness meditation produces shortterm increases in compassion.)

One form of lovingkindness meditation starts by cultivating compassion for the people close to you and then gradually widening the ingroup until it includes everyone―including your enemies. Does this practice help reduce hatred?

We don't know yet but at least one study shows that lovingkindness meditation reduces unconscious prejudice (as measured by the bias reaction time test) compared to a control group of "teaching participants about the value of loving-kindness meditation without actually teaching them the practice."

Reverse Habituation

Every kind of meditation I have ever heard of starts by training one's attention.

[In the 1970s researchers] brought an EEG machine to a zendo and measured monks' brain activity during meditation while hearing a monotonous series of sounds. While most monks showed nothing remarkable, three of the most "advanced" monks did: their brains responded as strongly to the twentieth sound as to the first. This was big news: ordinarily the brain would tune out, showing no reaction to the tenth bing, let alone the twentieth.

This constitutes objective external verification of my own and others' subjective experiences in zendo. It makes total sense if you are familiar with Zen and it is strong evidence that meditation may be a path off of the hedonic treadmill. Here is an anecdote of what it looks like outside the zendo.

Zen scholar D. T. Suzuki was a panelist at a symposium held outdoors. As he sat behind a table with the other panelists, Suzuki was perfectly still, his eyes fixed on a spot somewhere in front of him, seemingly zoned out in some world of his own. But when a sudden gust of wind blew some papers across the table, Susuki alone among the panelists made a lightning grab for them. He wasn't zoned out―he was paying keen attention in the Zen fashion.

Zen's priority is on mindful attention (as opposed to, say, lovingkindness) so we would expect one of the strongest effects within this tradition but increased attention is found in other traditions too.

Elena Antonova…found that meditators who have done a three-year retreat in the Tibetan tradition had less habituation of eye blinks when they heard loud bursts of noise.

Vipassana is so effective at increasing attention it changed scientists beliefs about what is biologically hardwired, especially with regards to attentional blink. It is hard to notice two stimuli in quick succession. Attentional blink is the amount of time it takes to notice stimulus after noticing stimulus $a$ .

Richie's group measured the attentional blink in vipassana meditators before and after that three-month retreat. After the retreat there was a dramatic reduction, 20 percent, in the attentional blink.

The key neural shift was a drop in response to the first glimpse of a number (they were just noting its presence) so the mind remains calm enough to also notice the second number, even if very soon after the first one.

That result was a huge surprise to cognitive scientists, who had believed the attentional blink was hardwired and so could not be lessened by any kind of training. Once the news was out in science circles, a group of researchers in Germany asked whether meditation training might offset the universal worsening with age of the attentional blink, which becomes more frequent and creates longer gaps in awareness as people get older. Yes: meditators who regularly practiced some form of "open monitoring" (a spacious awareness of whatever comes to mind) reversed the usual escalation of attentional blinks with aging, even doing better than another group taken entirely from a younger population.

The catch to all of this is that correlation does not prove causation. I would place a large bet that meditation (in particular, Zen) increases vigilance, but the final iron-clad results of a controlled, longitudinal study are not in yet.

Cognitive Control

Intelligence is really important. There is evidence fluid intelligence is related to working memory and in some cases might even be more important than IQ. If you can increase your working memory then you might be able to learn better.

[R]esearchers gave volunteers a two-week course in mindfulness…for a total of six hours, plus ten-minute booster sessions at home daily. The active control group studied nutrition for the same amount of time. Again, mindfulness improved concentration and lessened mind-wandering.

A surprise: mindfulness also improved working memory―the holding in mind of information so it can transfer into long-term memory.

I'm not sure exactly what definition they used of working memory but if this is true and the effect is significant then it could be huge for pedagogy (including autodidactive learning) and cognitively-demanding activities like computer programming. I write software better immediately after meditation but I didn't pay much attention to the effect before now. I'm not sure whether meditation actually increases my working memory or just cleans it out like a pressure washer. I predict the latter which is unfortunate because it means positive effects of meditation on working memory ought not to accumulate over time.

Meditation also increases impulse control and self-reported emotional well-being in a different study by Cliff Saron. This result aligns with my personal experiences.

A Quiet Mind

According to Buddhist lore, suffering is caused by unsatisfactoriness, non-self and impermanence. These are three kinds of attachment. Freedom from suffering comes from releasing attachment to the self, attachment to the state of the world and attachment to one's desires. Releasing attachment to one releases attachment to all. Freedom from suffering comes from letting go.

If we can identify the brain regions associated with self-worry then we can connect the subjective self-reports of Buddhist theory to neuroscientific observations. We could make enlightenment the subject of materially reductionist scientific research. The potential benefits associated with "cure for suffering" could be comparable to a cure for ageing.

The Default Mode Network

The default mode network is the part of your brain which dwells on your problems in your down time. The default mode network is the part of your brain that makes a wandering mind unhappy. It's the part of your brain that dwells on your problems when you're idle. Flow states free you from worries because they temporarily override your default mode network. Activity in your default mode network decreases when you focus your attention.

The default mode network is "mainly the mPFC (short for midline of the prefrontal cortex) and the PCC (postcingulate cortex), a node connecting to the limbic system. "When the meditators showed decreased activity in their PCC, they reported feelings like 'undistracted awareness' and 'effortless doing.'" The default mode network is so closely connected to a specific conscious experience that I think I can tell when it turns off when I'm meditating. Unlike the subjects of the research study, I have not verified my theory via brain imaging.

Sensory Dissolution

Another experience meditators consistently report is the deconstruction of sensory inputs into vibrations. This is best understood in terms of hierarchical ontologies. When you look at an image of a cat you might consciously process it as "a cat" (high-level) or as "a bunch of individual pixels" (low-level). By default, we tend to use the highest-level ontologies we can. However, it is possible to deconstruct an observation into low-level inputs. (This doesn't just happen in meditation; deconstructing a visual image into its primitive elements is Step 1 of learning how to draw.)

Meditators learn to deconstruct their high-level cognitive constructs into low-level sensory inputs. (This is analogous to deconstructing a theory into the raw data underlying it.) When you climb the ladder of abstraction down all the way to its lowest-level inputs meditators observe pure vibrations with no high-level meaning. Pain and suffering are above the lowest level of abstraction. Thus, perceptually deconstructing one's ontologies lets a person transcend pain and other forms of suffering (which is especially useful for people with incurable chronic pain). I predict these vibrations correspond to harmonic waves in the connectome. We don't have good scientific research on this phenomenon yet (that I know about) so I'm going to move on to non-self and non-attachment (which, according to Buddhist theory, are the same thing).

Letting Go

Meditation correlates with a reduction of gray matter in one key region: the nucleus accumbens. "A smaller nuclear accumbens diminishes connectivity between these self-related regions and the other neural modules that ordinarily orchestrate to create our self of self." This creates a physical measure connected to self-reports of "ego death". "[T]he nucleus accumbens plays a large role in the brain's 'reward' circuits" too, which ought to be connected to reports of how meditation reduces attachment.

Does all this "renouncing attachment" mean meditators live cold hollow indifferent existences? No. Definitely not. Meditators consistently report the opposite. There are dangers to watch out for (and I will address them at the end) but disconnecting yourself from pleasure is not one of them.

Richie once saw tears begin to stream down the Dalai Lama's face as he heard about a tragic situation in Tibet―the latest self-immolation among Tibetans protesting the Communist Chinese occupation of their land.

And then, a few moments later, the Dalai Lama noticed someone in the room doing something funny and he began laughing. There was no disrespect for the tragedy that brought him to tears, but rather, a buoyant and seamless transition from one emotional note to the other.

Aggregated Research

[T]wenty-one studies were combined to see what held up and what did not.

The results: certain areas of the brain seemed to enlarge in meditators, among them:

The insula, which attunes us to our internal state and powers emotional self-awareness, by enhancing attention to such internal signals.

Somatomotor areas, the main cortical hubs for sensing touch and pain, perhaps another benefit of increased bodily awareness.

Parts of the prefrontal cortex that operate in paying attention and in meta-awareness, abilities cultivated in almost all forms of meditation.

The orbitofrontal cortex, also part of the circuitry for self-regulation.

And the big news about meditation for older folks comes from a study at UCLA that finds meditation slows the usual shrinkage of our brain as we age: at age fifty, longtime meditators' brains are "younger" by 7.5 years compared to brains of nonmeditators of the same age. Bonus: for every year beyond fifty, the brains of practitioners were younger than their peers' by an additional one month and twenty-two days.

Unfortunately, this aggregated study suffers from all the usual problems, especially self-selection. (It also lump various kinds of meditation together―which is like putting powerlifters, biathloners, barefoot ultramarathoners and competitive eaters all into the single category of "athletes".) It could be that there is no causation and the apparent slowdown to brain aging is entirely due to a correlation between meditation and exercise.

Negative Effects

With all this talk of benefits from meditation I think a few words of warning are in order. There are side effects. Some side effects can be considered negative. Others side effects definitely are negative.

Normal people tend to ignore the most awful aspects of reality. Meditation gets you to notice them. This spirals some meditators into a vortex of misery, which we call the dark night of the soul. It's awful. If you think of minds in terms of stocastic gradient descent, the dark night of the soul is a bad local minima.

[Tales] of meditative dark nights do not always have such a clean resolution; the meditator's suffering can be ongoing long after leaving the meditation center. Because the many positive impacts of meditation are far more widely known, some who go through the dark nights discover people can't comprehend or even believe that they are hurting. All too frequently psychotherapists are little or no help.

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Dark nights are not unique to vipassana; most every meditative tradition warns about them.

For me, personally, I think the biggest danger isn't wireheading myself (which is a bigger danger to practitioners of samadhi) or getting trapped in a vortex of despair (which might happen if your ego refuses to let go of suffering). It's going crazy. The meditation I practice feels like staring into the maw of Cthulhu. I like this feeling because I feel mentally stable enough to ride out a Lovecraftian serving of existential horror. I relate to Daniel Ingram when he writes "Surfing the ragged edges of reality has been easier for me than slowing the thing down," but not everyone is on the same surfboard.

Yogis

All of the above studies are about meditators who live in civilization. The most impressive results come from yogis who live ascetic lives on Himalayan mountaintops as far away from civilization as they can get. Visiting these people is hard. Getting these people into an MRI is extremely difficult. Promises of wealth are completely ineffective. But the authors got a handful of them into brain scanners by appealing to compassion and the results were beyond anything they observed in civilized subjects.

Just as Mingyur began the meditation, there was a sudden huge burst of electrical activity on the computer monitors displaying the signals from his brain. Everyone assumed this meant he had moved; such movement artifacts are a common problem in research with EEG, which registers as wave pattern readings of electrical activity at the top of the brain. Any motion that tugs the sensors―a leg shifting, a tile of the head―gets amplified in those readings into a huge spike that looks like a brain wave and has to be filtered out for a clean analysis.

Oddly, this burst seemed to last the entire period of the compassion meditation, and as far as anyone could see, Mingyur had not moved an iota. What's more, the giant spikes diminished but did not disappear as he went into the mental rest period, again with no visible shift in his body.

When probed via fMRI the scientists found Mingyur's circuitry for empathy activated stronger than they had ever observed in normal people―a level normally associated with brief seizures lasting mere seconds. Mingyur sustained the activity for minutes and while being in full control of his brain.

They replicated these results with other yogis.

Epilogue: Waking Up

The coolest discovery happened almost as an afterthought, when the researchers examined the yogis resting brain state outside of meditation.

All the yogis had elevated gamma oscillations, not just during the meditation practice periods for open presence and compassion but also during the very first measurement, before any meditation was performed. This electrifying pattern was in EEG frequency known as "high-amplitude" gamma, the strongest, most intense form. These waves lasted the full minute of the baseline measurement before they started the meditation.

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Gamma, the very fastest brain wave, occurs during moments when differing brain regions fire in harmony, like moments of insight when different elements of a mental puzzle "click" together…. For that quick moment the gamma waves from each of these cortical regions [occipital, temporal, somatosensory, insular and olfactory] oscillate in perfect synchrony. Ordinary gamma waves from, say, a creative insight, last no longer than a fifth of a second―not the full minute seen in yogis.

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Our usual gamma waves are not nearly as strong as that seen by Richie's team in yogis like Mingyur…on average the yogis have twenty-five times greater amplitude gamma oscillations during baseline compared with the control group.

We can only make conjectures about what of consciousness this reflects: yogis like Mingyur seem to experience an ongoing state of open, rich awareness during their daily lives, not just when they meditate. The yogis themselves have described it as a spaciousness and vastness in their experience, as if all their senses were wide open to the full, rich panorama of experience.

I suspect gamma oscillations are associated with a phenomenon some traditions call "enlightenment". I wish I could offer a description of what it's like, but the experience is notoriously difficult to describe to a person who hasn't experienced it for one's self. It's like explaining to a deaf person what listening to music feels like.

Credits

This post was written with assistance from Less Wrong's feedback service. Thank you Swimmer963 and Ruby for the constructive feedback.

This post was funded by Less Wrong too. Thank you!

Other reasons: ① Freud wasn't into meditation. ② In reaction to Freud, the Behaviorist movement took over psychology for a while and it explicitly rejected the idea that your thoughts mattered. ③ There's not a lot of money in contemplation (compared to pills). Preemptively increasing one's mental health has little place in our disease-oriented treatment-based health system focused on physical ailments. ↩︎
Technically they proved a short-term boost to compassion causes a short-term boost to altruism. Ultimately we want to know whether a long-term boost to compassion causes a long-term boost to altruism. To find out whether it does, we must first confirm that it is possible to increase compassion long-term. Only after we have that technology can we test whether a long-term increase to compassion increase long-term altruism too. ↩︎