Intelligence – a very short introduction
I figured that as I was already spending time reading stuff on related matters, I might as well cover this topic as well (intelligence is not a personality variable they spend many paragraphs discussing in the Handbook) – but given that I’m not that interested in this stuff, I also figured I didn’t want to spend too much time on it. So reading a book with the subtitle ‘a very short introduction’ made sense.
The book is not very technical, and I was seriously considering as I was reading the first few pages to just throw it away. But I decided that I’d give it a few more pages, and having done that I realized that even though the coverage was somewhat superficial I might as well finish it as it would take very little effort. From the outset I sort of expected the book to be a ‘downgraded’ version of a standard Springer publication. It turned out that it was not, the level was significantly lower than that – either that or my conceptualization of how such a ‘downgraded’ (‘more accessible!’) book looks like was erroneous. Either way I was somewhat disappointed. I ended up giving the book two stars on goodreads. There was too much fluff and he spent a lot of time dealing with simple stuff.
Some of the conceptual and methodological approaches applied in this line of research are also applied in other areas of psychologic research covered in Leary & Hoyle, but you certainly don’t need to have read anything about psychology, psychometrics etc. in order to read and understand this book. To give an example of what I mean by the first part, in various areas of personality research it’s common for researchers to in some sense look for ‘common factors’ that tend to cluster together – the existence of such common factors relate very closely to the existence of such a thing as personality traits in the first place. The idea is that people who are in some sense ‘alike’ along one ‘dimension’ of personality/behaviours are likely to also be ‘alike’ along ‘similar’ related ‘dimensions’, and once you add the various elements in such clusters together and construct new variables and use these to have a closer look at stuff you might be interested in, these constructs can be used to gain a better understanding of behavioural links, because they tend to predict behaviour better than do the elements they’re made up of. You can add stuff together at more than one level if you like. The search for ‘g’ in the area of intelligence research is in some sense just a hunt for such a ‘common factor’; a factor useful in explaining variation in peoples’ performances at various cognitive tasks. The important point here being that most intelligence researchers agree that it makes sense to look for such a common factor, because it looks a lot as if such a factor exists in the data. A bit from the first chapter of the book about this stuff:
“Carroll’s strata of mental abilities emerged as an optimal result from a standardized statistical procedure, not from his imposing a structure on the data. He discovered rather than invented the hierarchy of intelligence differences […] Among psychologists working in this field there is no longer any substantial debate about the structure of human mental ability differences. Something like John Carroll’s three-stratum model almost always appears from a collection of mental tests. A general factor emerges that accounts for about half of the individual differences among the scores for a group of people, and there are group factors that are narrower abilities, and then very specific factors below that. Therefore, we can nowadays describe the structure of mental test performances quite reliably […]
The principal dissidents from this well-supported view are on the semi-popular fringes of scientific psychology. Howard Gardner’s popular writings on ‘multiple intelligences’ have suggested that there are many forms of mental ability and that they are unrelated. The facts are that some of Gardner’s supposedly separate intelligences are well known to be correlated positively and linked thereby to general mental ability, such as his verbal, mathematical, and musical intelligences. Some of his so-called intelligences, though valued human attributes, are not normally considered to be mental abilities, i.e. not within man’s ‘cognitive’ sphere. For example, physical intelligence is a set of motor skills and interpersonal intelligence involves personality traits.”
Here’s a little bit about ageing from the book (in the chapter he also talks a bit about the distinction between crystallized and fluid intelligence, among other things):
“what ages when we talk of intelligence ageing is something very general – some broad capability of the brain to handle ideas is changing, not just specific aspects of mental function […] what seems like a kaleidoscope of mental change can to a great extent be explained by one simple fact: as we get older our rate of processing information in the brain slows down.”
And below a few observations from chapter 3:
“there is a modest positive correlation between head size and brain size […] There is a modest association between brain size and psychometric intelligence. People with bigger brains tend to have higher mental test scores.” […]
“Psychologists today often refer to the ‘mental speed’ or ‘information processing speed’ ‘theory’ of intelligence. What they mean by that is that people who score better on intelligence tests might in part be cleverer because some key aspect(s) of the brain proceeds faster. My principal problem with this overall idea is that my colleagues can’t make up their mind how to measure this mental speed. Some use reaction times. Some use inspection times. Some use the brain’s electrical responses. Some even measure how long it takes electrical impulses to travel along people’s nerves. But these are all different measures, and it is an odd theory that can be tested without a common yardstick, and some of these mental speed ‘yardsticks’ don’t relate to each other very well at all. The truth is that we do not have an agreed measure of how fast the brain processes information, and that is because the workings of the nerve cells and their networks are largely mysterious. We must summarize by concluding, therefore, that intelligence is related to many things that involve speed of processing information, but that scientists have difficulty in conceptualizing ‘mental speed’ in a uniform way.”
I don’t really think it’s worth the trouble to cover more of the book in detail here, as a lot of the stuff covered in the book has already been covered here on the blog before – instead of reading the book you can just have a look at some of the stuff I’ve posted on intelligence before here – links like these: 1 (link vi.), 2, 3, 4, and 5 (not all of the stuff at the links is covered in the book, but I can’t be bothered to find all the matching papers and if you read the links in those posts you’ll probably learn more than you will from reading the book).
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