Updated: 3 days ago
The first thing to clarify is that IQ, working memory, concentration and crystallized intelligence are all different aspects of cognition. These are some of the building blocks of what we commonly call 'intelligence'. IQ is simply one aspect of this group of faculties that relate to intelligence.
There are other important mental abilities that cannot be tested on IQ tests. Creativity - i.e. associative thinking and divergent thinking - is not tested. Logic as applied to multi-faceted situations - which is most situations - is not tested. Problem solving is not tested. Essentially most forms of intelligence are not related to an IQ test. The IQ test measures speed and acuity of certain types of abstract cognition. As a pure measure of mental ability it's extremely limited. As we move beyond academia, personal qualities such as a personable nature and social confidence are both important predictors of success, but again neither are measured on IQ tests. Finally, work ethic and diligence, perhaps the most important aspects related to both academic and life success are not measured on IQ tests. Essentially, most aspects of generalized intelligence and most other useful traits are not measured on IQ tests.
If IQ is such an overrated metric, why is it still so widely discussed?
The main reason that psychologists, particularly American psychologists, like IQ tests so much is because it's an easy thing to measure. Psychology is a discipline that can measure very little. For a field wishing to be recognised as a hard-science, IQ tests were a boon. This led to them being enormously over-emphasised in importance by psychologists, sociologists and eventually employers.
What do we know about generalised intelligence?
IQ tests are not particularly useful in measuring intelligence. In fact, even the concept of generalised intelligence is not that useful in the real world. Intelligence is largely domain specific and tends to be highly localized - i.e. my ability in languages does not assist me in Physics, much less in driving a car. Even within one domain, such as verbal ability, intelligence is highly localized: my ability in French does not assist me with Portuguese. The notion of 'generalised intelligence' has limited real-world application. One commonly used phrase by some commentators writing about IQ is: 'An IQ test tests your ability to do an IQ test'. In my opinion, this is the most accurate thing an IQ test predicts. It is true that IQ does have some relationship to generalised intelligence and speed of processing, but it's just one of many factors.
The importance of work and application in developing real-world intelligence When you go to your lawyer or doctor, you don't care what IQ he has, you care about whether or not he has the relevant knowledge or training to assist you. This knowledge and training is achieved through discipline and study, not having a high IQ score. Conversely there are many people of high IQ, but lacking other things such as emotional stability, cultural upbringing and work-ethic that are unable to attain the kind of knowledge required for long term success in any field. There are plenty of high IQ men on the streets and prisons unfortunately.
American education versus European and British Education:
The US has always been obsessed with that test, while other cultures are much, much more focused on knowledge. The American SAT for instance is largely an IQ test - completely different to the European baccalaureate or the English A-levels. The European and English qualifications are subject-specific and require months of study, regardless of your native intelligence, a great deal of knowledge is required to succeed in the tests. Being quick enough to score highly in an IQ test simply will not cut it in the Baccalaureate or A-levels.
One significant weakness I see in the American system is the simple lack of higher level knowledge expected. A student can be mentally agile, but without the knowledge they lack reference points. I personally find the UK and European balance between knowledge and critical thinking skills to be a well-rounded approach. Overall, I think the European Baccalaureate gives the best preparation to secondary school students. My experience has been that Chinese, Japanese and South Korean systems focus mainly on knowledge and tend to have less interest in developing critical thinking skills. The US is really the exception globally. I expect that is because Universities want to get any student with even a modicum of potential through the doors. The SAT test is a reasonable tool for identifying students with potential and it can very easily be administered on a vast scale at low cost and high profit by the College Board.