I do not believe that IQ tests measure intelligence. Rather I believe that they measure a combination of intelligence, learning and concentration at a particular point in time. By learning I mean for example where tests contain words that are less familiar to the test subject (perhaps because the language is their second language), they might respond rather more slowly.
Also I believe that self-esteem can affect concentration. Quite some time ago I heard of a study that was done that seemed to confirm this belief. In the study, a group of students were first given an IQ test. Then the group was divided into 2 groups. The first group was subjected to verbal abuse and negative comments. The second group was given encouragement to increase their self-esteem. Then the 2 groups were given a second IQ test. Noticeable differences were seen in the results of the first and second tests which indicated that the verbal abuse and negative comments had caused a deterioration in the scores for the first group.
If such results can be observed after even such a short period of such verbal abuse, how much more profound could the result of a childhood of negativity received from parents or the wider community be having? A school that encourages self-esteem could for example be producing more apparently intelligent pupils.
Unfortunately I have not now been able to locate any information on this study, but if any readers know of it, I would be very grateful if you could provide any information. I think it was done in the 80s or 90s in New Zealand or Australia. The work of the psychologist Reuven Feuerstein seems to suggest something similar however.
Also other research into the effect of financial rewards for IQ tests have apparently shown that IQ scores increase noticeably when financial rewards are offered, and greater rewards also lead to greater increases.
All this does not mean that I believe that IQ tests are useless, quite the contrary. I also believe that individuals have different levels of innate intelligence, and that that is mainly genetically determined, but environmental factors such as nutrition also play a part. Certainly at least until we really understand how the human brain works, IQ tests are the only indicator we have of intelligence. What I am implying is that IQ tests should be recognized for what they are, a measure of intelligence, learning and concentration combined. We should certainly not therefore assume that people who only achieve relatively lower scores in childhood may not later do better in life than others who had achieved higher scores, even discounting the random misfortunes people encounter in their lives.