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Cognition

You Can Trust a Psychologist 95% of the Time, Part 2

Why psychological studies tell us about most but not of us

As I said in last month’s blog, psychological studies often rely on statistics for verification, and statistics simply tell us how likely research findings are representative of the whole population; they can never tell us that results are absolutely 100% guaranteed to be accurate (though if the result is subsequently repeated, the odds are usually in effect so massive that the results can be accepted).

However, that does not mean that the findings of psychological tests apply equally to everyone. Many of you will have experienced the feeling of reading results of research where someone pretty much like yourself is described, but nonetheless you do not identify with whatever psychological trait is being discussed. For example, I am an only child, and whilst I can recognise some personality traits I have in common with what psychologists say are typical singleton behaviours, there are others where I feel no identification at all. So does this mean that psychological studies are wrong?

The answer to this is that it depends upon how you define ‘wrong’. If you want psychological studies to mean all things to all people, then no psychological study on this earth will apply to everyone equally. For example, if I offered you the sexual fantasy of being whipped with stinging nettles by the British prime minister, almost everyone would be filled with revulsion, but it is a good bet that someone reading this would secretly like it. In short, statistical measures typically describe a general trend, not what will happen to each and every individual.

Thus, whilst psychologists are often good at telling us about most people, they are very rarely good at telling us about all people. There will always be the exceptions, and for this reason, you should never fall into the trap of thinking that what psychologists tell you automatically applies to you every bit of the time. ‘Aha!’ cries the skeptic, ‘I knew it! Psychologists are useless at telling us about everyday life’. Well, yes and no. Not being accurate about everybody is a failing, but this is far from unique to Psychology. Practically all measurements of the average, even highly objective ones, tend to be inaccurate on an individual basis. For example, although men are on average reliably taller than women, there are still some men who are shorter than some women. Again, although a particular make of automobile might be on average more reliable than another make, there will still be some individual cars of the more reliable model that break down more often than some individual cars of the less reliable model. Neither of these considerations would deter a sensible person from assuming that overall men tend to be taller than women or, when buying a car, taking into consideration that one model is likely to be more reliable than another model.

I also raise this point because all too often people look at ageing, grasp onto one aspect of it that applies to a group as a whole, and then assume that they will be the same. The simple fact is that there is no such thing as typical ageing. There are patterns of ageing that apply to a lot of people, but each individual will differ in some way. In fact, older people differ between each other in psychological skills and behaviour more than any other age group. I will (with a reasonably good probability value) return to this point in a later blog.

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More from Ian Stuart-Hamilton Ph.D.
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