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Tacit knowledge is more about solving problems than about knowing facts. This brings us to a very important distinction: the difference between the descriptive and prescriptive aspects of cognition and between the descriptive and prescriptive aspects of wisdom and competence. As we pointed out earlier, knowledge can be descriptive and prescriptive. So too can be pattern recognition and the attractors that embody it in the brain.
Descriptive knowledge is the knowledge about how things are. It is sometimes called “veridical knowledge.” Because things exist in the world independently of you, the observer, various statements about things can be judged as “true” or “false” regardless of your wishes and preferences. The statement “five plus five is ten” is true, and the statement “five plus five is twelve” is false. And if you wish that it were the other way around, then well, tough luck! Veridical, descriptive knowledge is the knowledge of the true nature of things.
By contrast, prescriptive knowledge is the knowledge not about how things are, but how they should be, and in particular it is the knowledge of what we must do to set them according to our wishes and our needs. Prescriptive knowledge is the knowledge of what needs to be done, the knowledge of the desired course of action. Unlike descriptive knowledge, prescriptive knowledge is not independent of you. Quite the reverse, it is knowledge about your needs and about the course of action that is best for you. Prescriptive knowledge is not the knowledge about the objective, “true” nature of things, but about the best course of action. Because the choice of such action is different for different people, I sometimes refer to it as actor-centered knowledge.
We humans are in command of the powerful mental machinery enabling us to acquire and store descriptive knowledge, but this machinery is secondary, ancillary, subordinated to our needs for the acquisition and storage of prescriptive knowledge. The evolutionary pressures that have shaped our brain and our body were directed at enhancing our survival and not our ability to establish the ultimate truth, even though the latter would be a nice facilitator of the former. And unless you are Diogenes living in a barrel, the primary objective for most people is to improve their lot, while finding the truth is a means to that end rather than the end in its own right.
With this in mind, it comes as no surprise that prescriptive knowledge is particularly valued, and so are prescriptive wisdom and prescriptive competence. People are more likely to turn to a sage or an expert for advice on what to do than for an explanation of how things are. The prescriptive power of wisdom and the prescriptive power of competence deserve a separate discussion.
To begin with, we need to understand where in the brain knowledge is formed and stored, and also how the difference between descriptive and prescriptive expertise is reflected in the brain machinery of knowledge. And for that we need to consider two major distinctions in the architecture of the brain: the distinction between the two hemispheres and the distinction between the front and back of the cerebral cortex. Both descriptive and prescriptive knowledge are based on pattern recognition, and the patterns are embodied in attractors. Since knowledge is stored where the information was first processed (remember, there is no designated, spatially separate warehouse of memories in the brain), the attractors embodying descriptive and prescriptive knowledge inhabit somewhat different neocortical territories.
Both descriptive and prescriptive knowledge are stored in the most advanced parts of the neocortex, known as the association cortex. Descriptive knowledge is stored mostly in its posterior subdivisions, in the temporal, parietal, and occipital lobes. By contrast, prescriptive knowledge is stored in the frontal lobes. Recent research has also shown that the two cerebral hemispheres play very different roles in knowledge acquisition and storage, in the formation of attractors, and in the machinery of pattern recognition.
In the next few chapters we will further explore the brain mechanisms of wisdom and competence and how these coveted traits depend on the two halves of the brain and on the frontal lobes. As we learn more about the frontal lobes, their intimate role in the acquisition and storage of prescriptive knowledge will become increasingly clear. And as we learn more about the differences and interactions between the two cerebral hemispheres and how they relate to new and familiar cognitive challenges, we will better understand what sets the wisdom patterns apart from other manifestations of the mind, how they come about, and what allows them to withstand the ravages of aging.
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There are some interesting differences between men and women with BDD. I’ve found that women are more likely to have an eating disorder, whereas men are more likely to have a problem with alcohol or drugs. Men are more likely to be single. While the sexes are generally similar in the number and areas of bodily concern, men are more likely to think that their body build is. too small, skinny, or not muscular enough, whereas women are more likely to dislike their weight and hips, thinking they’re too large and fat. While men and women are equally likely to have hair concerns, men are more prone to fear that they’re losing their hair. All of the people who worried about excessive body hair were women, whereas all of those with genital concerns were men. Men are more apt to use a hat for camouflage, whereas women are more likely to turn to cosmetics for cover.
These results are interesting because some of them echo normal appearance concerns and behaviors. Research findings indicate that women generally think their bodies are too large, whereas men tend to worry that theirs are too small. A study of college students, for example, found that 85% of the women wanted to lose weight, whereas only 40% of the men wanted to lose weight and 45% actually wanted to gain it. In the general population, concerns about balding are relatively common among men but not women, and women are more likely to use cosmetics than men.
Several treatment findings are also interesting. I’ve found that men and women are equally likely to seek nonpsychiatric treatment such as surgery or dermatologic treatment for their BDD concerns. They’re also equally likely to receive these kinds of treatment. This finding differs from what we know about the general population, in which women are more likely to receive cosmetic treatments than men.
The only other study that to my knowledge has investigated gender differences in BDD was done in Italy in a smaller series (58 people). This study, like mine, found that BDD was generally similar in women and men. And like my findings, women were more likely to have the eating disorder bulimia nervosa, and men were more likely to be concerned with their genitals. Unlike my results, however, the Italian study found that women were more likely to focus on their breasts/chest and legs, check mirrors, and camouflage, whereas men were more likely to focus on their height and excessive body hair. Certainly, we need more research on gender similarities and differences in BDD, not only in clinical settings but also in the general population and in different cultures.
I’m sometimes asked how many people with BDD are homosexual. I systematically assessed this in my series of 200 people with BDD and found that 5% were homosexual and 3% were bisexual. This percentage is somewhat higher than in the general population, but it indicates that the vast majority of people with BDD are heterosexual.
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After about twenty years research, the US National Aeronautics and Space Administration (NASA) has finally found a workable weapon in the war against indoor air pollution: house plants! Scientists working with space capsules always had to deal with small, cramped spaces in which astronauts spent long hours working without fresh air. Space vehicles are full, I am sure, of gadgets that pollute the air. They discovered that several common varieties of house plants are able to gobble up a wide range of contaminants, from benzene in tobacco smoke to formaldehyde in household cleaners. The Environmental Protection Association of the USA has found that the concentrations of some toxic chemicals in ordinary homes and office buildings are 200-500 per cent higher than those in the outside air. This is why the resulting health problems are sometimes called the ‘Sick Building Syndrome’. When they hear this term, people tend to associate the word ‘building’ with office blocks, skyscrapers and so on, without realising that their own home or flat is also a building.
As we have seen, common sources of pollutants are adhesives, carpeting, vinyl or rubber moulding, pressed wood, copying machines, cooking gas, cleaning agents and pesticides. There is no doubt in my mind that these can cause or aggravate a variety of conditions, including chronic fatigue syndrome. People who are very sensitive or already overloaded are affected by the chemicals buildings contain and usually complain of headaches, irritated eyes, drowsiness, skin rashes, difficulty in breathing and a host of other allergy-related conditions. Worse, these acute symptoms may be followed years later by more severe health consequences. We know that formaldehyde, benzene and trichloroethylene — three of the most common indoor pollutants — are able to reactivate dormant or latent viruses, and they are suspected of. causing a variety of cancers. According to the US government reports, indoor contaminants cost the nation tens of billions of dollars per year in lost productivity and medical bills.
As far back as 1973, when NASA found that the air inside Skylab 3 was contaminated with over 100 chemicals, space scientists realised they had a big problem. Environmental engineers were called in to solve the problem. Since plants recycle oxygen, one specialist reasoned, they might have a hidden talent for breaking down pollutants as well. So he exposed plants to high concentrations of different chemicals. The findings were interesting, to say the least:
Aloe Vera removed 90 per cent of the formaldehyde in the air within 24 hours.
Marginata reduced benzene concentrations by almost 80 per cent.
Peace Lily cut trichloroethylene by 50 per cent.
Since no one plant can tackle all pollutants, the scientists suggest cultivating a mixture of plants which excel at breaking down different classes of compounds. One or two plants per 10 square metres is usually sufficient, though severe problems may require air venting or removing pollutant sources as well.
To maximise anti-pollution capabilities, a ‘filter planter’ or high-tech flowerpot has been developed. The container holds a hydroponic growth medium of carbon and porous clay pebbles which traps pollutants more effectively than ordinary soil.
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