Here are some key quotes:
"...recently, a psychologist named Amishi Jha traveled to Hawaii to train United States Marines to use the same technique for shorter sessions to achieve a much different purpose: mental resilience in a war zone.The author posted some negative results of mindfulness as follows:
“We found that getting as little as 12 minutes of meditation practice a day helped the Marines to keep their attention and working memory — that is, the added ability to pay attention over time — stable,” said Jha, director of the University of Miami’s Contemplative Neuroscience, Mindfulness Research and Practice Initiative. “If they practiced less than 12 minutes or not at all, they degraded in their functioning.”Jha, whose program has received a $1.7 million, four-year grant from the Department of Defense, described her results at a bastion of scientific conservatism, the New York Academy of Sciences, during a meeting on “The Science of Mindfulness.”[...]In addition to military fitness, scientists are now testing brief stints of mindfulness training as a means to improve scores on standardized tests and lay down new connections between brain cells.Michael Posner, of the University of Oregon, and Yi-Yuan Tang, of Texas Tech University, used functional M.R.I.’s before and after participants spent a combined 11 hours over two weeks practicing a form of mindfulness meditation developed by Tang. They found that it enhanced the integrity and efficiency of the brain’s white matter, the tissue that connects and protects neurons emanating from the anterior cingulate cortex, a region of particular importance for rational decision-making and effortful problem-solving.Perhaps that is why mindfulness has proved beneficial to prospective graduate students. In May, the journal Psychological Science published the results of a randomized trial showing that undergraduates instructed to spend a mere 10 minutes a day for two weeks practicing mindfulness made significant improvement on the verbal portion of the Graduate Record Exam — a gain of 16 percentile points. They also significantly increased their working memory capacity, the ability to maintain and manipulate multiple items of attention.
“For some people who begin mindfulness training, it’s the first time in their life where they realize that a thought or emotion is not their only reality, that they have the ability to stay focused on something else, for instance their breathing, and let that emotion or thought just pass by.”
"But one of the most surprising findings of recent mindfulness studies is that it could have unwanted side effects. Raising roadblocks to the mind’s peregrinations could, after all, prevent the very sort of mental vacations that lead to epiphanies.[...] If you’re driving in a difficult situation, if you’re operating machinery, if you’re having a conversation, it’s useful to hold that focus. But that could be taken to an extreme, where one always holds their attention in the present and never lets it wander.”
"In a study presented at the Society for Neuroscience annual meeting in November, they found that the higher adults scored on a measurement of mindfulness, the worse they performed on tests of implicit learning — the kind that underlies all sorts of acquired skills and habits but that occurs without conscious awareness.[...] “We know that being mindful is really good for a lot of explicit cognitive functions. But it might not be so useful when you want to form new habits.” Learning to ride a bicycle, speak grammatically or interpret the meaning of people’s facial expressions are three examples of knowledge we acquire through implicit learning — as if by osmosis, without our being able to describe how we did it. (Few of us can recite the rules of grammar, though most of us follow them when we speak.)"The first issue - that of the mind not being allowed to wander seems to be a conceptual imposition on the practice since it's impossible to stop the mind from wandering - the basic 'brain muscle building' of bringing attention back to focus on an anchor every time it wanders is testament to the fact that the mind wanders all the time during mindfulness practice. There is no record of anyone practicing modern mindfulness whose mind does not wander, so it is a strange notion that mindfulness means no mind wandering.
The second study assuming that implicit learning is not facilitated very well by mindfulness is also strange, since the traditional 'mindful arts' of the East were often taught through emulation - going with the flow. It would be interesting to know more about how that study was conducted and to see what other experts in the field have to say about it.