Ill health, whether physical or mental, can have
deleterious effects on cognitive functioning. Current research efforts are
attempting to understand what these effects are and what can be done about
them. In the course of this review, it is shown how the methods of psychology
from the developed world can be applied to the problems of the developing
Suppose there were a malady that attacked very large
numbers of American, British, French, or German children. The malady rarely
resulted in catastrophic consequences, such as death or permanent
disfigurement, although it did cause a variety of kinds of serious physical damage,
such as stunting of growth, chronic diarrhea, and potential organ damage. More
importantly for our purposes right now, it also had a cognitive effect: At
moderate to high levels of infection, it resulted in stunting of cognitive--not
just physical--growth, to the tune of, say, 5 to 7 IQ points.
What, exactly, would the loss of 5 to 7 points of IQ mean? The first thing we
need to realize is that we are not really just talking about 5 to 7 points of
IQ. That's at an individual level. At a national level, in a moderate-sized
country, say a mere 10 million children were affected. Then we are talking
about 50 to 70 million IQ points. In a larger country with 100 million children
affected, we are talking about perhaps 500 to 700 million points of IQ. The
affected children may be losing not just IQ points, but other kinds of
abilities as well, such as creative and practical intellectual abilities
(Sternberg, 1985). What do such effects mean in practical terms, whether the
losses are in the kinds of analytical abilities measured by conventional
intelligence tests, or in creative or practical abilities?
At some level, we all know. Some supermarkets now
have computerized cash registers that, seemingly, any moron can operate. There
is no need, as there once was, actually to do any arithmetic computations, so
the systems seem, on their surface, to be dummy-proof. A problem arises,
however, not when the system is working perfectly, but when it isn't, as when
the system is unable to handle a product that has not been bar-coded, or one
that has been miscoded. That's what happened to one of us just a couple of
weeks ago. The checker hadn't the faintest idea of what to do. Neither did the
smiling so-called customer service representative. Meanwhile, the line got
longer, and the author's patience wore thin. The supermarket lost him as a
customer, and perhaps several other customers as well.
The other coauthor had an experience in a movie
theater of wanting a cup of water. They had no water to offer. She asked just
for a cup. They wouldn't give her a cup. She offered to buy just the cup for
the price of a soda. They wouldn't sell the cup without the soda in it! She had
to buy the cup with the soda, dump out the soda, and fill the cup with water from
The malady we are talking about, though, does not
affect just the children who later become supermarket checkers who quickly
become check-mated, or soda jerks at movie theaters. It affects children who
later become doctors, and maybe are not quite as accurate in diagnosing and
treating illnesses as they might have been, or military leaders who do not
really know how to negotiate with their opponents and who therefore see the
battleground as the only solution, or defense lawyers who get confused and end
up arguing effectively for the prosecutor rather than for their own clients.
And it affects individuals in developing countries who must cope with often
harsh and unforgiving environments.
The sad fact is that this malady is not just a single
malady but a whole string of them: inadequate nutrition, ingestion of toxic
substances, various kinds of parasitic infections, even severe anxiety or
depression, and the like. These maladies are having right now the effects to
which we refer above, but in countries where the kind of rapid, vocal,
international press coverage that would be generated in the United States,
United Kingdom, France, or Germany just doesn't come about; or when it does, no
one seems much to care. What is worse is that all of these maladies are
treatable, usually at low cost. But they often go untreated because of a lack
of interest, or a lack of funds.
Are the effects debilitating? Absolutely. A team of
us representing a collaboration among Yale, Moscow State, and Oxford
Universities has recently reviewed the literature on different kinds of
physical maladies, including micronutrient deficiencies of various kinds,
ingestion of toxic substances, and parasitic infections of various kinds. One
can argue about strengths of effects, which of course can vary with severity of
insult (see, e.g., Ricciuti, 1994; Watkins & Pollitt, 1997). But we have
arrived at what we believe is a straightforward conclusion: These maladies can
make a significant unfavorable difference to cognitive functioning (Sternberg,
Grigorenko, & Nokes, 1997).
At some level, we do not need even one research study
to show the effects of these maladies. Almost everyone has experienced the
effects themselves, although only acutely and at extremely low levels of
intensity. All people have probably had at least one occasion on which they
either missed dinner or had a very light dinner, and then didn't have time for
breakfast the next morning. Maybe they even missed the lunch that should have
preceded that dinner. Now it's about 11:00 a.m. the next day and they are
perhaps sitting in a lecture hall listening to a complicated lecture on
something that really doesn't interest them much; or perhaps they are giving
the lecture. At that moment, they may be finding that the lecture interests
them even less, because that lecture is the furthest thing from their
mind--they are thinking about lunch. And they will get it.
Millions and millions of children, however, will not
get that lunch, or will get a lunch so low in essential nutrients that they
will still be hungry and nutrient-starved after the lunch. They probably won't
get much of a dinner either, or breakfast. They are not thinking about what
they are hearing either. For them, the teacher's droning voice is the furthest
thing from their minds, as it will be tomorrow, and the next day, and the day
The first time one of us took the tests we use for
admission to college in the U.S.--the SAT--he was just getting over
mononucleosis. He did not feel well at all. And he felt even worse when he took
a final examination in college while he had a full-blown case of the flu. He
could hardly concentrate on either test. He didn't totally fail either the SAT
or the college examination. But his performance was compromised, as probably
would be the performance of most people in similar situations, when they would
have rather been, and would have been better off being, in bed.
Ironically, it is not just the disease that is
debilitating them, but their own body (Nesse & Williams, 1994). Their body
is telling them that this isn't the time for them to be engaging in strenuous
mental activity, or, of course, physical activity. The body needs all the
resources it can muster to fight the infection. It may even be generating a
fever to create an environment that is hostile for the microorganisms that are
attacking the individual, but an environment that also happens to be hostile to
the individual's concentration on whatever he or she is doing.
Physical Well-Being and Analytical Abilities
A billion children are parasitically infected, and hundreds of millions,
undernourished or malnourished (Bundy, 1994). Often the same children are both
undernourished and infected. And their bodies are telling them that today--every
day--isn't the day for serious mental effort. The result is that these children
are likely to be building up a cumulative deficit in cognitive skills, which is
likely to stay with them their whole life.
The Jamaica Study
Why do cumulative deficits remain? After all, many of these children later will
become better nourished, or will rid themselves of the parasites infecting
them. In order to answer this question, consider a collaborative study done in
Jamaica by a team from Yale, the University of the West Indies, and the British
Institute of Child Health, and funded by the Partnership for Child Development
(Sternberg, Powell, McGrane, & Grantham-McGregor, 1997). The study was of
the effect of whipworm infection (Trichuris trichiura) on cognitive
functioning. Children typically acquire such infections when they put dirt in
their mouths, and ingest worm eggs that are harbored in the dirt.
Sternberg et al. (1997) designed a battery of
cognitive tests to be administered to Jamaican school children of
elementary-school age (grades 4-5). The 196 children were asked to perform
perceptual tasks, such as visually searching for a particular letter in an
array of letters; a formboard task, which measured primarily perceptual-motor
speed; memory tasks, such as remembering numbers or words; and reasoning tasks,
such as solving analogies and series-completion problems. Some of the memory
and reasoning tests were of the kinds found on typical psychometric tests of
intelligence. The tests were administered twice, both to children who were
infected with intestinal parasites (whipworm) and to ones who were not. Half
the infected children were treated with an antiparasitic
medication--albendazole--and the other half were administered a placebo (until
after the study was over, at which time they were also treated with
albendazole). All children took the tests before any kind of treatment, and
then they all took the tests again later, after administration of either
treatment or placebo, or, in the case of the uninfected group, after an equal
amount of time had passed.
What did we find? We found, first, that the
parasitically infected children, on the whole, performed at a lower level on
the cognitive tests than did the noninfected ones, even after we controlled for
obvious potential confounding variables, such as sex and socioeconomic status.
Second, we found that the impairment in cognitive functioning was not equally
distributed across the different kinds of tests. Rather, almost all of the
impairment was in the memory and reasoning tests, which measure the kinds of
functioning measured by tests of intelligence, and that are also relevant to
success in school. Third, we found that treatment with albendazole resulted in
no immediate increase at all in cognitive functioning. These results held up
even when we controlled for effects of socioeconomic class differences.
Some of the more medically oriented types to whom we
mentioned these results were surprised as well as disappointed that
administration of the antiparasitic medication did not result in an immediate
increase in cognitive scores. After all, if one takes a test while one has the
flu, one's performance may very well be affected, but if one takes the test
after one is over the flu, one's performance will quickly return to the higher
level that it would have shown before one had the flu.
The difference in our study was that there was no
prior higher level of performance to which to return. Many and probably most of
the children had been chronically infected--maintaining infections and
reinfecting themselves year after year. It is not hard for the children to do.
All they have to do is get dirt in their mouths. With other kinds of parasites,
such as schistosomes, which enter through the skin of the feet, the children
only have to walk or swim in bodies of water in which the parasites reside in
order to be infected.
Medication can potentially make a more nearly
immediate cognitive difference. If one can get the children treated early, before
infection becomes chronic, or if one tests children with only acute infections,
the results of antiparasitic treatment can be immediate, dramatic, and lasting,
as shown by Nokes and her colleagues (Nokes & Bundy, 1994; Nokes et al.,
Parasitic infections can occur anywhere, even in the
more developed countries (Bundy, 1994). Treatment is cheap and it is easy to
administer. But we need more research on the cognitive and physical effects of
the parasites, on treatments, and on the kinds of health-education measures we
can provide that will be effective. Moreover, we need to develop effective
cognitive interventions for children of all ages, because the effects not only
of parasitic infections, but of poor nutrition cumulate, so that medical treatment
is not sufficient to make up for the years that are likely to be lost when the
children were not able to learn and think as effectively as they would have
been able to had they not had these maladies. These interventions can be
effective if only we have the will to implement them (see, e.g., Honig, 1994;
Nickerson, 1994; Ramey, 1994; Sternberg & Grigorenko, 1997).
The Tanzania Study
Although there has been some research, the conclusions to be drawn are not
unequivocal (Watkins & Pollitt, 1997). There are clearly effects, but
different studies suggest different ones. In current research in Bagamoyo,
Tanzania, which is sponsored by the Partnership for Child Development and which
we are doing in collaboration with a team from Oxford led by Dr. Donald Bundy
and coordinated by Dr. Kate Nokes, as well as a team from the University of Dar
es Salaam led by Professor Akundaeli Mbise, we are investigating a kind of
testing that may show an immediate effect of medical treatment, even for
chronically infected children.
We believe that what a medical or nutritional
intervention can do is to put children in a position where they are now able to
learn. What it cannot do is put children in a position where they immediately
recover the lost opportunities of the years during which they were infected. If
our hypothesis is correct, then tests that actually allow learning at the time
of testing may show immediate gains as a result of the medical or nutritional
treatment. We are using such tests in our research. Thus, this research goes a
step beyond the earlier Sternberg et al. (1997) study, in using dynamic rather
than static testing. Such testing is called "dynamic testing," as
opposed to the conventional static kind of testing to which we are accustomed
in cognitive-ability assessments, which measure prior rather than current
learning (Feuerstein, 1979; Grigorenko & Sternberg, 1997; Vygotsky, 1978).
In this study with Tanzanian school children, we have been using three kinds of
The first is a syllogisms task, in which children are
given problems such as "Alan is taller than Ken. Dan is taller than Alan.
Who is the tallest, Alan, Ken, or Dan?" Children complete a pretest, then
are given instruction in how drawings can be used to improve performance (e.g.,
one can imagine a line with Dan at the top, followed by Alan, and then, Ken),
and then are given a posttest. The task is given in the children's language,
Kiswahili, not in English.
The second task is a 20-questions task, where
children are required to identify the object the examiner is thinking of.
Again, there is a pretest and a posttest, with instruction in the middle on how
maximally to narrow the field of possible objects. The third task is a sorting
task, where children have to sort objects according to rules.
Our research is still in progress, but the
preliminary results are promising. At the very least, we know that the tests
are reliable, and that they measure skills somewhat different from those
measured by conventional static tests. We do not know yet whether the tests
will discriminate between the treated and untreated children. However, another
study in which we do have results shows that dynamic testing can work, and that
it can make a practical difference in skills needed for effective adaptation in
developing countries by people from developed countries.
The Foreign Service Institute Study
In order to interact effectively with people abroad, one needs to know their
language. The U.S. Foreign Service Institute trains government workers from
many branches in the foreign languages they will need in order to work
effectively abroad. In collaboration with Madeline Ehrman, we devised a dynamic
test of foreign-language learning ability in which test-takers learned an
artificial language--Ursulu--at the time they took the test (Grigorenko,
Sternberg, & Ehrman, 1997). The test required the test-takers not only to
learn the language, but also to show their knowledge as they learned it.
The artificial language itself was fairly complex,
but not clearly related to any one particular language or language group. The
test yielded oral and written scores, as well as scores on a number of
language-learning skills. We were pleased to discover that scores on the test
correlated more highly with scores on another test of foreign-language-learning
ability than it did with conventional tests of intelligence, suggesting that
the test is measuring, more or less, what it is supposed to measure. Moreover,
and more importantly, scores on the test correlated about .7 with grades in
foreign-language learning at the Foreign Service Institute--across the
languages learned there. In other words, the dynamic test, in which one learned
at the time of testing, was a very good predictor of who would be able to learn
a new language well and then use the new language abroad.
Mental Well-Being and Practical Abilities
Virtually all of the cognitive testing that has been done has not only been
static, but has also looked at what we believe to be a relatively narrow range
of abilities. According to the triarchic theory of intelligence (Sternberg,
1985, 1988, 1996), intelligence involves not only analytical abilities, but
also creative abilities and practical abilities.
The U. S. Studies
Our research on adults as well as children in the U.S. has revealed, for
example, that practical intelligence is unrelated to the more analytical, or
academic aspect of intelligence (Sternberg, Wagner, Williams, & Horvath,
1995). Put another way, some of the people who are highest in common sense do
not test particularly well on intelligence tests.
For example, one study investigated bank vice
presidents in a large bank chain, and found that measures of practical
intelligence that required simulations of problems faced on the job predicted
various kinds of performance ratings about twice as well as did IQ (Sternberg,
Wagner, & Okagaki, 1993; Wagner, 1987). The measures the investigators
devised did not correlate with intelligence-test scores, however.
It is important to realize that tests of practical
intelligence, like any other tests, assume a set of values. What is valued in a
given culture; what is not? Values enter in both with regard to the types of
items used, and to how they are keyed. For example, the same items that might
measure practical intelligence in one culture might measure nothing of
consequence in another culture. Moreover, practical-intelligence items
measuring appropriate behavior for a bank president or sales person might have
to be scored differently across cultures. For example, the hard-driving sales
techniques that might be valued in one place might not be valued at all in
another. Consider a study we are doing in Kenya.
The Kenya Study
We are currently working with the Oxford team of Drs. Bundy and Nokes, Danish
anthropologist Dr. Paul Wenzel Geisler of the Danish Bilharziasis Laboratory,
and a Kenyan team led by Professor Frederick Okatcha of the Kenyatta University
of Nairobi, to study the effects of parasitic infections on practical
intelligence. What we want to know is whether these infections deprive children
not only of IQ points, but of the common-sense, practical skills immediately
needed to survive.
We are studying infected and non-infected children
for their practical intellectual skills in treating their own infections, and
are also investigating the relation of these skills to IQ-based skills, which
we expect (consistent with the triarchic theory of intelligence) will be
minimal. So far, we have piloted about 30 fourth- and seventh-grade students in
We are giving two types of test. In the first test,
children were presented with 101 words in their native language, Luo, 78 of
which were names of real herbs and 33 of which were false-positive stimuli
(nonherbs). The children were required to tick off the names of the real herbs,
and for each real herb, to write the illnesses for which it could be used. The
total recognition score was calculated so that respondents were penalized for
false positive choices (saying a word represented an herb when it didn't). In
the second test, children received an inventory with 29 different stories
addressing illnesses and herbs used to treat those illnesses. Students had to
show their knowledge of which herbs treated which illnesses. The correlation
between the two tests was .50.
One of our preliminary findings, we believe, is quite
interesting: The tests of knowledge of natural herbal medicines for treating
infections correlated about - .45 with tests of conventional, crystallized
intelligence, in particular, vocabulary tests whether administered in the
English or the indigenous Luo language. In other words, children who are better
socialized into the indigenous Kenyan rural culture are more poorly socialized
into the formal school culture, and vice versa. Perhaps parents, and their
children, make a choice in terms of their socialization.
The Kenya study underscores an important point about
comparing cognitive functioning across cultures. One cannot merely go in and
assume that whatever cognitive measures we use in our own culture measure the
same thing in another culture. Some children in Kenya may have found the
English-language vocabulary test intimidating. But imagine how children in the
United States would feel if they were administered a test of natural herbal
medicines used to fight various kinds of illnesses. For the most part, they
would not be able to answer even a single test item correctly. Knowledge that
is considered adaptive in the Luo rural culture here would be considered to be
of little value; but the reverse can often be true as well. Adaptation is also
differentially difficult in different places.
The U.S.-Spain Study
Practical intelligence is not fixed. It can be taught. In a study conducted in
collaboration with investigators led by Dr. Howard Gardner at Harvard
University, our team at Yale showed that practical intelligence can be
effectively taught to urban, suburban, and rural school children at the grade 5
to grade 8 level, resulting in statistically significant and substantial gains
in academic performance (Gardner, Krechevsky, Sternberg, & Okagaki, 1994;
Sternberg, Okagaki, & Jackson, 1990). Experimental groups who received our
Practical Intelligence for School Program (Williams et al., 1996) improved
significantly more from pretests to posttests than did control groups who did
not receive the program. Underlying this research is the notion that many
children may actually have the academic abilities to do well in school, but not
understand the expectations that the school has for them. This program has been
translated into Spanish and used in Spain by Professor Jesus Beltran, of the
Complutense University, with comparable results.
Nutrition and parasitic infections may have effects
on practical intelligence that are different from the effects they have on the
more academic aspects of intelligence. Indeed, children growing up in very
challenging environments may have to develop skills that children in more
privileged environments do not have to develop. What this means is that
children could have a low level of IQ but a high level of practical
intelligence, or a high level of IQ but a low level of practical intelligence.
For sure, all of us know people of both kinds. Indeed, one of us was reading a
newspaper a few weeks ago, and there was a story about the president of one of
the larger banks in the U.S. The author was chagrined to realize that this very
successful bank president was a student he had known who had been enrolled in
his elementary and secondary schools, and had been a C student. In the U.S.
this man was not labeled as "intelligent." Would he have been seen as
The Russia Study
Consider, for example, adaptation in modern-day Russia, which we are now
studying with the support of the National Council for Eurasian and East
European Research. The deceptively simple question "How are you?" can
convey many different meanings. So, too, can the various possible answers to
How do people answer the question "How
are you?" when, unaccustomed to catastrophe, they are confronted by a war,
earthquake, drought, or nuclear accident, or when their society as a whole
undergoes tremendous change, causing significant financial and psychological
To begin to answer this question, we conducted a
study that explored various affective and cognitive dimensions of mental health
and subjective well-being among mothers in Russia, where recent dramatic
changes have affected the entire population. The current situation in the
former Soviet Union provides an excellent opportunity for studying how people
from all socioeconomic backgrounds are experiencing the stressful effects of
financial, institutional, political, and societal uncertainty and instability.
At this time of fluctuating values and beliefs, restructured economic and
political institutions, and redefined standards of well-being and success, all
citizens are feeling the stress of adapting to changing conditions. Such
large-scale social upheaval has, in a sense, homogenized Russians from a
variety of educational, national, religious, and other social groups.
Consequently, we were able to investigate the differences and similarities in how
people of different SES levels, marital statuses, ages, personality traits, and
educational backgrounds experience large-scale societal change and to explore
what determines people's perceptions of their adaptability and success in a
radically changed society.
Four types of variables were investigated as
indicators of women's well-being: (1) emotional well-being, as determined by
the absence of anxiety or depression; (2) perceived control over one's life;
(3) life satisfaction and attitude toward current societal changes; and (4)
perceived change-related stress. This subjective well-being was explored in the
context of four groups of variables previously identified as predictors: (1)
demographic and job-related characteristics, (2) health-status indicators, (3)
personality traits, and (4) level of family functioning.
In addition to these traditionally investigated
predictors of contentment, we studied the contribution of intelligence to
subjective well-being. Drastic societal changes have touched people at all
levels of educational attainment and intellectual ability; the working class
and the intelligentsia alike have found their incomes and lifestyles adversely
affected by these transformations. In the majority of Western studies, people
from different socioeconomic backgrounds have scored differently on
conventional measures of intelligence, but sociological studies in Russia show
that financial problems there are striking citizens regardless of educational
level. Considerable anecdotal evidence suggests that many Russians are making
dramatic career changes in response to societal transformation, but that others
seem incapable of modifying or unwilling to modify their careers and to adjust
to new realities. Consequently, dissatisfaction has increased, especially among
those who have found themselves unable to provide for their families. This
evidence has led us to explore the roles various types of intelligence play in
channeling current societal changes through families. For this study, we relied
on Sternberg's "triarchic theory of intelligence," which posits that
intelligence can be structured in terms of a "triarchy" of abilities:
analytical, creative, and practical. Specifically, we investigated the roles
analytical intelligence and practical intelligence played in subjective
The sample included 494 women who were enrolled in
the study through their children. Students from two different age groups (280
ten- and eleven-year-old children and 233 fifteen- and sixteen-year-old
adolescents) attending public schools in Voronezh were asked to give their
mothers a letter describing the study and requesting participation. Voronezh is
a representative Russian city in which students from different socioeconomic
backgrounds attend the same schools because few private specialized schools
exist and residential patterns are such that prosperous and more financially
strapped families live in close proximity. The mothers were invited to come to
the school to fill out the relevant questionnaires. Mothers provided basic
demographic data, such as age, income level, marital status, educational level,
and number of children. Then, more extensive information on subjective
well-being and predictive variables was gathered through a series of measures
An interesting finding concerns the role of
intellectual factors in predicting various components of well-being.
Specifically, practical abilities were associated with such aspects of
subjective well-being as freedom from depression, life satisfaction, feelings
of control over the present and future, and perception of current societal
changes. In general, relatively high practical ability was associated with more
adaptive feelings and behaviors. That is, mothers with strong practical
abilities tended to be less depressed and to feel more in control of and
satisfied with life than were those with lesser practical abilities. Yet, women
who viewed recent societal changes as mostly negative tended to have high
practical abilities. Certainly, life in Russian today is difficult: Salaries
are not paid regularly, education and health care are undergoing major changes,
political institutions seem fragile, and the danger of civil war still looms.
It may be, then, that women with relatively high practical abilities simply
perceive the present situation accurately and adapt, running their lives
satisfactorily even in the context of shifting conditions that they view as
Moreover, we found a significant link between high
levels of crystallized abilities and two of the indicators of subjective
well-being: (1) feeling of control over one's present life and (2) perceived
stress associated with uncertainty about parenting and raising a family.
Crystallized abilities were negatively associated with the perceived stress of
raising a family, suggesting that women with high verbal intelligence tend to
be less overwhelmed than do others by the challenges of the "new"
life and to be more secure about transmitting "old" moral and educational
values. Nevertheless, higher levels of crystallized abilities were associated
with lower feelings of control over one's current life.
Another, somewhat surprising finding, was the low
predictive power of recent so-called "life events." Only two of these
events--the beginning of a career and retirement--were found to be related to
This study has helped to illuminate the dynamics of
well-being in a milieu of societal uncertainty and instability. These
particular Russian experiences help us understand how human beings find
satisfaction in their lives, even under tremendous amounts of external
long-term stress. In addition, this exploration of the experiences of
women--still the primary nurturers of future generations--contributes to a
growing body of research on the role played by women's social and emotional
well-being in children's maladaptive development.
The Taiwan Study
Cultures have different adaptive requirements related to intelligence, and even
different conceptions of what intelligence is, or whether there even is such a
thing as intelligence. The Chinese language, for example, has no single word
that corresponds exactly to our word for intelligence. When we studied in
Taiwan implicit theories (folk conceptions) underlying the word in Chinese that
most closely approximates the English word for intelligence, we found five
underlying factors (Yang & Sternberg, 1997). The first factor was similar
to a general intelligence factor. The other factors were interpersonal
intelligence, intrapersonal intelligence, intellectual self-assertion, and
intellectual self-effacement. These factors were very different from those we
had formerly obtained in the United States (Sternberg, Conway, Ketron, &
Bernstein, 1981). In other words, one cannot just assume that, in other
cultures, the conception of intelligence, or even what constitutes desirable
cognitive abilities, will match our own. We need first to investigate the
properties and conceptualizations of the culture in which we are working, preferably
working with collaborators from that culture.
The bottom line is that in any study of cognitive
abilities outside our own culture--including studies of the effects of physical
ill health on such abilities and of the effects of these abilities on mental
health--we must be very cautious in defining our constructs and in doing our
research. We cannot merely assume that the cognitive skills we value, or label
as intelligence, are those valued or labeled as intelligence in another
culture. It is for this reason that we have collaborated with psychologists
from the cultures in which we are working, and we have done analyses of
conceptions of intelligence in these cultures rather than assuming that their
notions of intelligence equal ours. Such understandings are needed to study the
cognitive costs of ill health.
What We Know About Cognitive Costs of Ill Health
So what, exactly, are the cognitive costs of ill health? We believe several
conclusions are supported by the best of the available data (Sternberg,
Grigorenko, & Nokes, 1997):
With regard to poor nutrition, we know that
short-term hunger results in impaired attention in school-age children, which
leads to decreased academic performance. Long-term poor nutrition and
protein-energy undernutrition, including kwashiorkor and marasmus, result in
cognitive and social-emotional impairment, with little improvement upon
nutritional recovery. Cognitive intervention for these children is a must.
With regard to specific micronutrient deficiencies,
the evidence suggests that (a) low levels of dietary zinc can lead to a range
of children's cognitive and social-emotional problems; that (b) iron
deficiency, which is very common in some underdeveloped regions, leads to
cognitive underachievement--including reduced IQ and reduced attention span--in
both infants and schoolchildren, which can be reversed unless the children have
developed severe cretinism; and that (c) vitamin A deficiency can lead to
academic impairment, especially as mediated through effects on vision.
With regard to infections, (a) HIV infection, which
has become increasingly common worldwide, typically has neurological effects
that results in cognitive impairment; that (b) respiratory illnesses, unless
severe, result in only temporary impairments that are reversible; and that (c)
various kinds of worm infections, at high moderate to high levels, can result
in cognitive deficits in high-level mental skills.
With respect to toxins, toxic substances, such as
alcohol (usually absorbed in utero) and lead (usually absorbed through the
environment, such as through eating of paint) can also result in moderate to
severe cognitive impairments, in the case of alcohol, even at low doses.
The question now is what we are going to do about all
this. Do we want to support the research and development? People can ask
themselves what they would do if there were a malady--easily studied and
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