(continue from your brain and your life)

Although the concept the race is a social construct which has conveniently been hijacked by naïve people as a “shorthand” to refer to groups originated from different geographical areas (ref. my post on “racism in the genomic era”) . Nevertheless, for the sake of debating, I here succumb myself to this “shorthand”. This does not mean I agree with this definition of race.

The controversy on racial IQ difference practically stigmatizes blacks. They have been labeled as “less intelligent” which is certainly not a pleasing description. But how much “stupidity” they are? Are they really THAT dumb?

The assertion that blacks are less intelligent than whites can be traced back to the time of American founding fathers when black slaves were discounted during the population poll and thought as half-human-half-animals. Early studies showed that the average IQ was 85 in African American and 70 in sub-Saharan African which was at the level of moron. In comparison, the East Asians had an average of 106, and whites had 100 in IQ test. This order was confirmed among different population, at different times, and using different IQ measurements. This pattern of 1.1 standard deviation difference persisted from childhood to adulthood despite IQ increases with physiological growth. Even at highly educated level, blacks on average had lower IQ score than their white peers.

In addition, during last fifty years, the black-white gap in IQ measurements in the United States has narrowed, but the large difference persists. The Head Start program, aiming to improve education for kids from poor family (blacks are disproportionally represented), hasn’t yielded many benefits. Studies found that despite the significant effects on these kids appeared in earlier age, the effects didn’t last long. It seems that blacks are doomed.

Because IQ tests rely on responders’ linguistic skills and are also affected by culture differences, objective measurements are more desirable. Reaction time measures the speed of response on simple questions and presumably reflects the neurophysiological efficiency in the brain, thus providing more accurate assessment of intelligence. Using this measure, blacks still showed far slower reaction time than East Asian and whites. Intelligence scores summarized from different reaction time measurements reached the same conclusion. There is no hope here either.

Brain volume, either measured in old fashion such as size and weight, or using fancy techniques such as magnetic resonance imaging (MRI), suggested that blacks had smaller brains than whites, while East Asians had the largest brains. Larger brain may have more brain cells and nerve connections. It may be more sophisticated to do mental work.

Given numerous consistent findings that blacks are not as smart as whites, it seems that at least there is a racial difference in IQ related intelligence. It is a plain fact, no doubt about it.

Well, I agree that there is a racial difference in IQ. However, how these “objective” measurements relate to intelligence is questionable. The correlation coefficient between IQ and MRI brain volume is about 0.40; and it is even far less between IQ and head circumference measures. The correlation coefficient between IQ and intelligence index from multiple reaction time measurements is at most 0.67. Quantitatively, they are not much.

Further, the logic of the evidence goes like this: IQ is positively related to brain volume; blacks have smaller brains than whites; then it must be true that blacks have lower IQ than whites In fact, the logic is false. Among studies Rushton cited in his review, most are unrelated studies and didn’t measure brain volume and IQ simultaneously among blacks and whites. They are irrelevant to answer whether brain size difference causes IQ difference between blacks and whites. In his study which indeed measured IQ and head circumference among 50,000 children, he only examined the relationship between cranial size and IQ in Asian children, but used the above logic to extrapolate his racial idea. An appropriate analysis should examine whether there is an interaction between cranial size and race in relation to IQ, ADJUSTED for potential confounders such as socio-economic status, family influence, and educational characteristics. Unfortunately, all of his cited studies during above discussion fell into “correlation or exploratory” studies with no careful adjustment. The correlation analysis can’t answer any causal factors.

As I have pointed out in the last post, studies following up people for some time, in particular those experimental studies can shed light on the causes of racial difference in IQ. To answer whether the cause is genetic or not, studies such as twin studies or adoption studies are particularly useful. They not only explore the genetic and environmental interaction, but also follow up the subjects for a long time to trace the IQ changes with education. They are also superior to common family studies in that the twin or adoption studies have an element of “natural experiment” which is desirable in dissecting cause and effect relationship.

To be continued….

The literate people are those who can read and write, while those illiterate ones are unfortunately labeled as ignorants. However, not many people realize that reading characters or alphabets are not biologically born to it. It is a technique we learn from rigorous training.

Research on reading difficulty, or dyslexia, can be traced back to nineteenth century. An English doctor reported several children who were extremely “stupid”–who could not be taught to read and write. However, the understanding of dyslexia is a modern science. It is not until 1970s and earlier 1980s that researchers fully understood the mechanism of reading. That is, one needs to learn how to link phonetic sound to visual written alphabets. A staging framework was proposed based on observations from children’s learning to read.

Basically, children first learn how to speak. Many sounds and associated meanings are processed and stored before they start to read. The broca’s area in dominant side (mostly left brain for right-hand people, not sure about left hand people, for example myself :-)) is actively involved in this stage. When time comes to learn to read, normal children will relate those characters or alphabets to the familiar sound–through sound to meanings and to text. For normal children, a word is visualized as a whole thing, and the related information such as pictures around the word help the mechanical process from sound to word, and word to meanings. It is not uncommon for parents to discover that a child who knows the word “that”, which has no visual meaning, in one picture book, but fails to recognize it in another book. Nevertheless, by mechanically associating the sound of “that” with the alphabets, children store a fairly large vocabulary before knowing how to pronounce the sound of each syllabus. That is why parents need to read aloud to their children, in particular read with them.

The breakthrough occurs when children realize that the alphabets have phonetic rules and intentionally apply these rules in reading. During this stage, the vocabulary expands exponentially. After grade 3, most normal children have developed to such a level that there is no explicit need to read aloud words to understand the meaning of the text. At the same time, the Wernicke’s area, the semantic processing area also develops progressively to facilitate the reading process. This new functional area in left brain and vast connections among brain areas which deal with sounds, text, meanings, and semantic process are established. A shortcut from text to meanings is created (presumably in werniche’s area). One should note that boys are more likely to activate only the left brain during the first stage of reading, while girls can activate both sides of brain, which is why there are fewer dyslexia children in females than in males.

However, for those dyslexia children, they have difficulty to associate the text with sound, in particular those words with no physical pictures such as “that” and “is” (as also the case for many normal children). Further, the semantic area is not well established in these children, although the understanding and thinking process (in other brain areas) are not impaired. It should be note that after carefully training, most of them will create somewhat compensation in the non-dominant brain. Therefore, many dyslexia children experience the slowness of reading, but are good at abstract thinking and visualization. Their intelligence is not impaired.

Nevertheless, the above theories, confirmed by numerous studies, are proposed and tested in people who speak phonetic languages such as English. An unsettled question arises: what about those who don’t speak phonetic languages, for example Chinese people?

A recent article in Nature examined this issue. Their functional magnet resonance imaging (fMRI) experiments concluded that there are culture differences in learning process and in activated brain areas. It is not surprising considering the great plasticity of brain. Although Chinese language has been developed into a morphosyllabic system, the segments of a Chinese character have no inherent meanings related to the whole character (for most Chinese characters). The reading process may require three different activities from sound to the meaning of words: phonology, orthography and semantic meanings, while the orthography is less important in English.

In that study, the reaction time for two homophonic characters was impaired in dyslexia Chinese children, thus confirming the phoneme theory that the link between sound and text is impaired among them. That there is no difference of accuracy of meaning between normal and dyslexia children further supports the theory that the understanding and thinking process is not impaired. In addition, brain imaging revealed that several brain areas involved in Chinese reading, and dyslexia Chinese children have several areas impaired, in particular the left middle front gyrus, the visual word form area that serves orthographic-to-semantic integration. Nevertheless, this research is a significant addition in understanding reading process and dyslexia.

What are the implications to common Chinese people who are struggling in English? Not much. If one can read and write Chinese without difficulty, one can read and write English with ease too. In fact, brain areas and activities for learning Chinese may be supersede the functional areas associated with learning English. All connections are well established in normal Chinese readers. It is possible that Chinese people may have more advantages in learning English than those English speaking people learn Chinese. In fact, most Chinese students in the US have no difficult listening, reading, and comprehending English within months after their arrivals.

Then why do many people feel so dismayed in learning English? Based on my experience, the difficulties lie in the semantic part during speaking and writing process. The large English vocabulary and mechanical composition of them should not be difficult for most normal people, as it is evident that many Chinese students can overcome the vocabulary hurdle in merely several months, although the subtlties of words are still difficult to master. However, English, and many other phonetic languages, have a very complicate grammatic system. Speaking and writing in English require one to pay attention to details such as plurals, small words, and grammartic consistency. The subtle differences in meanings among words are beyond the phonetic realm. Chinese adults literally reconstuct a whole new system to use English. There is a great confusion in brain areas that deal with semantic meanings. In addition, the fine details of wording and grammars take a life long time to overcome. Even for a proficient English native speaker, grammatic errors are unavoidable. Because adults’ brain areas are fixed to some extent, it takes a longer time to master these fine parts for Chinese. On the other hand, the grammar is not a big issue in Chinese language. Very few native Chinese speakers struggle with Chinese grammar.

Even though the outgoing brain part such as Broca’s area is normal, and indeed there is a lot of information inside the brain, because the confusion is inside the semantic part of brain, one typical problem in Chinese English is that all the words in a sentence are correct, and most are accurate, but the grammar is incorrect. This puzzles the native speakers because their brain can’t process the disconnected words without grammar. Many Chinese students find it frustrating and inhibiting after hopeless attempting to arrange the same words in different erroneous ways.

A few final words. I found the book “overcome dyslexia”, written by Sally Shaywitz is very interesting. Although my son is actually way ahead of his peers in reading, I still found the theories scientifically presented in this book are very informative and enlightening. In addition, the book prescribes a detailed process and associated materials to help normal children start to learn and be a proficient reader. I highly recommend this book to all serious parents. It clarifies many puzzling questions during Child’s learning process.

For some, the IQ, intelligence quotient, is a magic word. Knowing that one has a high IQ definitely boosts his/her self-esteem, even though he/she may be in a career trouble. A widely held view is that Jewish and Asians have the highest IQ, followed by whites, both of which are slightly above average (100), while blacks are stigmatized by having the lowest IQ. There is no doubt that something fishy is behind this conclusion; but ironically, empirical results repeatedly show the same order of IQ by race, although some inconsistencies exist.

The recent effort by (in)famous Philippe Rushton from the U of Western Ontario and Arthur Jensen from UC Berkeley demands some attentions, if not critiques. The 60-page review in the current Psychology, Public Policy, and Law (2005, 11:2 235-294) traced 30 years of research on racial differences in intelligence measurements. An interesting note is that the authors used “cognitive ability” instead of “intelligence” in the title, presumably to broad the paper’s scope and assume an objective attitude.

This lengthy review concluded that the racial difference in intelligence indeed had genetic component. It was the group biological characteristics, not the social or environmental factors that underlay the racial difference of intelligence. Although some may be offended and willing to jump onto them and beat them to death, cool-headed researchers would like to choose a more scientific approach. That is, we need to critically evaluate their evidence and interpretations.

Given the massive evidence, complicated study design, and possible misinterpretation even among trained researchers, several evaluation criteria should be established beforehand.

First, what kind of research we value the most? There are several types of studies. At the first line is the ecological study in which the population average differences of IQ are compared and sought to be explained by population level (group level) characteristics such as average education or income. However, the group level variables don’t necessary reflect the individual characteristics. For example, those having lower IQ may have higher income, even though at the group level, those affluent countries had average higher IQ than those poor African countries. Due to this ecological fallacy, this type of study would be discarded as evidence.

The second line study is cross-sectional study at individual level. Here everything is assessed at individual (person) level. However, in terms of explaining whether race, biological and social factors are causal factors of IQ differences, the cross-sectional studies are of little value, except for exploratory purpose. The reversal cause-effect pathway is always possible. Causes should occur before effects. Therefore, interpreting results from these studies should be cautious.

To solve the time problem, observational follow-up studies in which individuals are followed for a certain period to collect the outcome of interest, are of the most importance, given that experimental studies are not practical and rare in social science. In experimental studies, people are assigned to different groups (either randomly or quasi-randomly). Random experimental studies are “gold standard” for causal inference. Fortunately, there are “natural experiments” such as migrations, adoption studies, and twin studies which have similar power to assess causal effect as those experimental studies. I will emphasize these studies in later discussion.

Next, what is the intelligence? An uneducated person may be a skilled craftman. Nobody will say he/she is not intelligent. On the other hand, the popular IQ only measures reading, memory, mathematics and logic, and some motion abilities. It is not a complete and accurate representation of intelligence. It excludes aspects such as emotion control, leadership, and athletic abilities which are more important in future success. Furthermore, IQ is measured based on tests, mostly in verbal and written language, thus subjected to bias. Objective measures are more relevant. In Rushton’s review, the authors indeed focused on measures such as brain size and weight, reaction time, and even brain metabolic activities using functional magnet resonance imaging (fMRI). However, how these measures relate to general intelligence is largely unknown.

The third important point one must keep in mind that “the cause of individual differences within groups has no necessary implication for the cause of the average difference between groups” (p5). That is, although intelligence has a large part of genetic component (e.g., more than 50% heritability) which may explain IQ difference between Joe (black) and Jane (white), it does not necessary explain the difference between overall black and white difference. It is very possible that social factors such as education between blacks and whites may cause the group level difference, as it is well known that blacks have low average education.

Finally, the concept of heritability should be carefully defined. Heritability is computed as the genetic contribution to the individual differences in a particular population, statistically assessed by percent of total variance explained by genetic variation. Therefore, the heritability is a concept of proportion or probability. It is used to describe population, not individuals. Given the complicate gene-gene, gene-environment, and environment-environment interactions, there is no specific gene that fully explains the intelligence. Even if a phenotypic trait such as intelligence is largely genetically determined (which is not necessary true), environment such as education can change it.

Now we are ready to formally critique the review (please forgive me for the above lengthy preamble). The debate is “whether any significant part of the mean black-white IQ difference is due to genetic rather than purely cultural or environmental in origin”. Notice that the question is at group level, not at individual level. In addition, it is also possible that the contribution of environmental factors to IQ may be different within blacks and whites. For example, education may be more important in improving one’s IQ in one group than in the other group. The same is true for genetic contributions, that is, the effect of genetics may be different within blacks and whites. Therefore, the statement that the difference of mean IQ between blacks and whites is due to genetics actually says that given the same environmental conditions, blacks still have lower IQ than whites. The inference is made from subtraction, an indirect method.

The hereditarians assert that the persistent racial difference of IQ (and intelligence in general) is due to genetics, even if everything else is the same. On the contrary, culture-only sociologists (environmentalists) hold the view that it is social environment factors that explain the racial difference of IQ. Improving these factors will eliminate the IQ difference. One needs to remind him/herself that it is not uncommon in science that the same results may have different interpretations, and both could be true.

Now here come my critiques.

My first question is what the race is. With convenience, race is commonly defined by physical characteristics such as skin color and facial shape. It is more politically correct to define race based on geographic origin such African, East Asian, and European descendents. Ideally, one wish to define race based on genetic composition such as polymorphisms if we assume race exist as a biological term. Given the pervasive racial mixture in the US and Latin America, most blacks have some percent of white “blood”. Therefore, the genetically deterministic view between whites and blacks in the US is skeptical (discuss in detail later). Nevertheless, racial comparison worldwide still makes sense given most African never travel out of their hometown.

To be continued……

A recent study warned that for one unit increase of perceived racial discrimination, there was a threefold higher risk of coronary arterial calcification, an early sign of coronary heart disease. This study was conducted on Chicago and Pittsburg women.

It is not the first study, and certainly will not be the last study, linking racial discrimination to heart disease, or health in general. However, the theory from discrimination to health is still murky.

Recent psychosocial theory focuses on stress and relates it to physiological illness provoked by perceived discrimination, in addition to actual physical environment (such as worse residential housing) and mistreatment (such as lack or inappropriate medical treatments). However, conservatives such as Sally Satel refuted the discrimination idea that it was because the highly sensitive people were more likely to develop heart disease. One could never be sure whether the perceived discrimination existed or not.

This cynical view is wrong. It reverses the cause-effect direction. The discrimination that minorities perceive may be subtle, but only in the eyes of dominant groups. The existence of discrimination has been recorded by numerous studies. In fact, physicians have always claimed themselves fair, but it has been repeatedly shown that they prescribe different treatments between blacks and whites, even if the diseases and symptoms are the same. Another study used anonymous call to assess the discrimination in real estate. It found that those who pretended to be blacks received higher interest rate and worse house than those who pretended to be whites. The subtle discrimination is not trivial at all.

Because it is not possible to design an experimental study in which people are randomly assigned to different race, whether the perceived discrimination is a real discrimination can not be definitely answered. The debate will go on and on.