Handwashing Behavior - Or: Should I take the Peanuts?

particles on the skinMinuscule particles between dermal ridges in the hand, hardly seen by the naked eye. via wikipediaI don't think I am obsessed with personal hygiene, although, I am averse to certain behaviors, such as when you pick your nose next to me and then flip your snot in my direction, or when you reach out to touch me after having been touching dirty things on the street. What sometimes sets me off is seeing people exit the bathroom without washing their hands. I was also surprised, that when toilets featured shared faucets, to see this frequently with women (or should I say rather, not to see it). Now what about the peanuts in the bar? The guy, who just grabbed 10 more peanuts than his hand could hold and let half of them fall back into the bowl, what did he touch before? Should you really eat any of the peanuts? How many people wash their hands anyways?

In 1847 Ignaz Semmelweis showed that hand washing of midwives helped to reduce significantly mortality rate of childbed fever, from aroud 10 percent to around 1 percent, although at the time, he became rather unpopular for it. In 1890, Robert Koch demonstrated that anthrax was caused by the bacterium Bacillus anthracis and provided evidence for Pasteur's germ theory. Despite the implications for hygiene being so clear, it is again a case of theory against practice as case studies show.

Results from studies on hand washing behavior vary, debited in part to experimental protocol. Amanda Stinson concluded in her article "Hand washing behavior of women in public bathrooms", that due to an increased self-awareness, subjects were more likely to wash their hands when someone else was present washing their hands. Stinson distinguished between three conditions in her study on hand washing behavior of women:
  1. No observer was visible
  2. A person is talking on the cell phone next to the faucet
  3. A person is washing her hands

She found that overall only 40 percent of young women washed their hands. In the hand washing condition (3), the subjects were more likely to wash their hands, 56 percent, while in the cell phone condition (2), subjects were less likely to wash their hands 27 percent. Stinson also found a strong and highly significant negative correlation between the time of night and whether or not the subject washed her hands.

In some studies it is not very clear whether the social factor mentioned above was taken into account so it is difficult to compare data over different studies. It also becomes clear from another study (see below), that age and education could be correlated variables. I therefore mention only one more study to compare men and women's hand washing behavior.

In the study "Gender and ethnic differences in hand hygiene practices among college students" by Anderson and colleagues it is not completely clear how they observe people in restrooms, however they make no mention of controlling the social variable and I would speculate that the difference from the results above could be explained in terms of social pressure.

What they found is that men washed their hands in 38 percent of cases and women in 62 percent,hand hygiene in females would be better than in males. In the discussion, Anderson and colleagues reference earlier similar evidence. They provide the argument that females' higher compliance could be associated with their tendency to practice socially acceptable behaviors. This however would also mean that having somebody watch you in the bathroom would have a stronger effect on women than on men, so that the question of who is more hygienic, men or women, cannot be answered conclusively.

Interestingly, Anderson and colleagues found that the minority students exhibited better hand hygiene practices than the Caucasian students. Comparing other studies they find that hand washing behavior in this college student population was only slightly higher than in populations of middle school and high school students. As for adequacy of hygiene, they report that only a small proportion of those who washed their hands did so for 20 seconds.

To come back to the original question: should I take the peanuts? I think that's a question of priority: just how hungry are you?

Enjoy those peanuts. At least as long as you can. Please leave a comment below for questions and suggestions. If you liked this article you might also want to read about the speed of nail growth.
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Atheism around the World

The rate of atheism or agnosticism in different countries is a question which can commonly sneak up in discussions over dinner or lunch. Atheist writers, such as Richard Dawkins and Christopher Hitchens, argued that belief in "a bearded man in the sky" — to take a somewhat provocative verbal expression — interferes with perception of reality.

While there are few people who would go as far as to actually claim that rate of religious belief is inversely proportional to national intelligence (see below), some people may take a high rate of believers as a measure of backwardness. Intuitively, I would guess it is probably relatively safe to claim that atheism rate is indicative of education level and economic well-being. I found a map of atheism worldwide, which I show, I outline the argument around atheism, and give a short discussion.

The data in the map come from different sources and are subject to different sorts of methodological differences and should therefore be taken with a grain of salt. Please, click on the link for a list of sources and to get a bigger image.



In many developed countries, people go to church on at least four occasions baptism, confirmation, wedding(s), and funeral(s). Some time ago, I wrote an article about belief in evolution worldwide, with a graph included that looked quite similar to this one.

I promised a discussion of the argument that religious belief is a sign of backwardness, so here it comes.

Is National IQ Related to Atheism Rate?

Richard Lynn, one of the discoverers of the Flynn effect, published together with others the study "Average intelligence predicts atheism rates across 137 nations." In it, after reviewing previous supportive studies, the authors find further evidence for significant negative correlation of IQ and religious belief within nations.

So, there you have it.

However, then the problems begin and I have to take this detour to distance myself from other results of this study.

They then go on to correlate national atheism rates with national IQs as Lynn previously had compiled in a book, mostly based on Pisa international education assessment studies and find again a negative correlation of educational success and religious belief over populations of different countries.

Rather than arguing for a correlation of education with atheism, the authors argue for a correlation of national IQ and atheism rate, which is not unproblematic. The main problem are methodological confounds about how to define/calculate national intelligence. They include factors of economic development (see below). Further, the authors argue backwards, saying basically that people are religious and uneducated because they are stupid (genetically).

The Flynn Effect and Atheism

It is worth to point out at this point that Lynn's claim to fame beside the Flynn effect is his quest to find racially conditioned differences in intelligence. I am therefore making a detour to point out the confusion of concepts and because I don't feel comfortable in citing a study by Lynn without qualification. Lynn states on his departmental web page:

In 1991 I extended my work on race differences in intelligence to other races. I concluded that the average IQ of blacks in sub-Saharan Africa is approximately 70. It has long been known that the average IQ of blacks in the United States is approximately 85. The explanation for the higher IQ of American blacks is that they have about 25 per cent of Caucasian genes and a better environment.

An abstract of one of his papers, Sex differences in intelligence and brain size is no less controversial: A paradox resolved, reads:
Males have larger brains than females, even when corrected for body size, and brain size is positively correlated with intelligence. This leads to the expectation that males should have higher average levels of intelligence than females. Yet the consensus view is that there is no sex difference in general intelligence. An examination of the literature shows that the consensus view is wrong. Among adults, males have slightly higher verbal and reasoning abilities than females and a more pronounced superiority on spatial abilities. If the three abilities are combined to form general intelligence, the mean for males is 4 IQ points higher than the mean for females. Among children up to the age of around 14 yr the sex differences are smaller because girls mature earlier than boys. The evolutionary selection pressures responsible for greater intelligence in males are discussed.

The article "Why national IQs do not support evolutionary theories of intelligence" delivers rebuttals for most of the claims (emphasis is mine):

We show that these studies assume that the Flynn Effect is either nonexistent or invariant with respect to different regions of the world, that there have been no migrations and climatic changes over the course of evolution, and that there have been no trends over the last century in indicators of reproductive strategies (e.g., declines in fertility and infant mortality). In addition, we show that national IQs are strongly confounded with the current developmental status of countries. National IQs correlate with all the variables that have been suggested to have caused the Flynn Effect in the developed world.

In fact, in the book mentioned above, Lynn and his co-author, Vanhanen, find correlations between the national IQ, as they calculate it, and many other factors. The human condition index (QHC), which they derive in the book, is found to be very highly correlated with national IQs. The QHC is composed of the following:
  1. purchasing power parity Gross National Income (PPP-GNI) per capita 2002
  2. adult literacy rate 2002
  3. gross tertiary enrollment ratio
  4. life expectancy at birth 2002
  5. the level of democratization 2002.
One of these factors is education, which they use to calculate their IQ scores, so a high correlation is not too surprising. Basically the whole argument of national IQs boils down to saying religious belief correlates negatively with factors such as purchasing power parity, literacy rate, education, life expectancy, and others. I find it both ironic and sad, that Lynn forgets about the effect he helped to discover.

Concluding, religious belief (or rather the absence) seems to be one of the indicators of development.
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