A couple of weeks ago, the kind folks at Psychology Today asked me if I wanted to do a blog for the PT website. I said yes before anyone discovered their mistake, and so here I find myself contemplating my first blog with only a borderline psychotic African grey parrot for company as I type away at the keyboard. I am guided in my writing by the helpful list of don'ts supplied to authors by PT. I thus promise to avoid using provocative images of body parts. Or at least, I certainly won't be offering views of my body parts as I really would like you to live happy lives. The photograph that the kind editors of PT have found is in any case sufficient to challenge anyone's view that beauty can be found in all things. Lest you were wondering how anyone can have such a happy face, suffice to say that the title of the challenging portrait is 'Fourth Attempt to Find a Photo Booth That Works on the Hottest and Most Humid Day of the Year'. 

So what do I promise to offer in this blog of mine? My principal area of interest is the psychology of aging. I shall spend most of my time boring you with articles of greater or lesser erudition based on that subject but will occasionally go off at a tangent if I think there is something else of interest that you will enjoy or will stimulate you. For example, how many of you have ever considered the problem of sample sizes in Williams syndrome research? I know, it's a topic that you've always meant to get round to reading, but never have. Well, fear not - here in a few brief paragraphs is all most of you are ever likely to want to know.

Williams syndrome (WS) is a genetic disorder affecting approximately 1 in 20,000 children. It is caused by loss of genetic material from a region of chromosome 7 very soon after fertilization of the egg. Although very rare, in its most archetypal cases, it produces some of the most startling symptoms of any learning disability. Children with a full set of symptoms have shortened stature and facial features that have been accurately described as elfin (as in the elves in fairy stories, rather than Mia Farrow or Audrey Hepburn). Psychologically, they typically have lowered IQ and a remarkable over-friendliness that will lead them to greet complete strangers with hugs. You would suppose quite reasonably that such unusual symptoms would be noticed by clinicians, and indeed a trawl of the archives will produce a number of case studies of children who clearly have what we would now classify as WS. But because the condition is so rare and is due to a completely by chance genetic malformation after conception (i.e. it does not run in families) clinicians usually just saw one case in a lifetime and did not realise that there might be other examples out there.

It thus took until 1961 for a Dr. Williams and colleagues to make the discovery that the condition was more than a one-off occurrence, when they reported four children in New Zealand with similar symptoms. By one of the curious coincidences so common in research, an earlier study of calcium disorders in children had almost identified the condition, and some Russian researchers (headed by Professor Beuren) discovered the same syndrome utterly independently a few months later (hence why WS is called Beuren myopathy or Williams-Beuren syndrome in some countries).

Because WS is so rare, relatively few studies have been conducted on people with the condition. However, in recent years, interest has grown in WS because (rightly or wrongly) researchers have become interested in WS as a condition to contrast with Autism Spectrum Condition (ASC). The argument runs that while WS children have an excessive desire for social contact, children with ASC have an underdeveloped desire for the same. The result has been a plethora of studies of WS children, often using small samples (under 10).

My concern here is not the validity of the ASC-WS comparison, but with the size of the samples of participants. Can 10 or fewer children be considered a representative sample? And alas, the answer is probably no. A few years ago, I started supervising a very ingenious and hard working clinical psychologist from Greece, called Antonios. He had, over the years, tested a lot of children with WS, in each and every case making a scrupulous record of all their symptoms and getting them fully genetically tested. When we analysed his data, we had a surprise. The size of the genetic loss differed greatly between the children, and so did their range of symptoms. Put simply – the greater the genetic loss, the greater the number of symptoms. However, you could not say with certainty that a particular size of genetic loss meant a specific number and type of symptoms. Two children with the same level of genetic loss might have drastically different symptoms.

Now Antonios had a sample of more than 70 participants, so we were able to work through the data with some chance of accuracy. However, what of studies that have taken a group of 10 or fewer children as representative of WS? The chances that these samples truly represent WS are slim.

Now I can hear the protests at this statement already –  namely, larger sample sizes are impossible to get, so we have to make do with what we can find.  I have a lot of sympathy with this view, and I think that along the same lines of half a loaf of bread is better than no bread at all, we should make use of what we have if nothing else is possible. But I am concerned that somewhere down the line, people will read the findings of studies on WS, not realize that they are based on (too) small samples, and start making assumptions that all children with WS ‘must’ be the same. And this does not only apply to WS: there are a lot of relatively rare developmental disorders where small sample sizes are the only possible option open, but where there is potentially a wide range of disability within the condition. Our picture of some learning disabilities is thus more compromised than people might believe.

Rather than end on this slightly gloomy note, I offer a postscript just to show how small and beautiful a world it can be. After Antonios gained his doctorate, he moved from Greece to New Zealand. He was posted to a hospital, the very same hospital where Dr. Williams had made his discovery.

You are reading

The Gift of Aging

Are Bicycles Alive?

Why a lot of people think at odds with reality as they grow older

What the exception to the rule proves

Most psychological findings are generalisations - how does this create problems?

What Constitutes General Knowledge?

Why 'general knowledge' can be a misleading term.