Limitations of IQ Test
There exists no universally accepted definition of Intelligence, simply because every culture and ethnic group interprets it in a different manner. Perhaps; this is the reason why "The Guinness Book of World Records" has removed the category of "The most intelligent person in the World", as the only criteria available to them was the IQ test, which they may have considered inaccurate.
Within the scope of Psychology, various approaches have been adopted to understand the human intelligence. The "Psychometric" approach is the most common and also the most important in terms of practical use. The IQ test is derived from a number of tests, designed to assess the level of human intelligence. The scope and limitations of the test is still controversial, despite its utility in acquiring a rough idea about the intelligence level as well as the education of a person.
The argument is; can the IQ score represent the intelligence level of a person in terms of numerical ranking? Now this question gives rise to several other questions like; can we find the level of human intelligence with psychometric alone, does it take into consideration the diverse cultural and ethnic backgrounds of candidates, can all IQ tests that are used today can be termed as reliable, if the purpose of the test is to predict the future achievements of a person, how far does it really serves the purpose, etc.
Accuracy of the Test Itself
When we try to find any accredited work against the accuracy of IQ test, the importance of the book The Mismeasure of Man (1981), written by Psychologist Stephen Jay Gould of Harvard University, cannot be denied. In this book Prof. Gould disagrees with the concept of considering human intelligence as a single entity that can be measured in mathematical number, to grade people according to their score. In the second revised edition (1996), he has criticized the The Bell Curve, a 1994 book by psychologist Richard J. Herrnstein, which suggests that IQ test can be used to predict the future achievements-- like carrier and other events in life - even the chances of unwanted pregnancy.
Factors affecting the performance of the Candidate
In an IQ test, we only find out the response of that person on a given day and time. Same person may score differently on different occasions, depending upon many factors such as; health and emotional condition, knowledge of language, incentive, practice, test room conditions, etc. There is one more point that even without any education and practice of undergoing tests, one cannot perform in an IQ Test, the way experienced and educated people do.
Cultural and Ethnic Background
The cultural and ethnic background of both; the test developer and the candidate also have their own implications. It is impossible that the test may be culturally neutral. Moreover; different cultural and ethnically diverse groups may have different approaches to a subject. It is a well established fact that, the students belonging to diverse cultural and ethnic backgrounds are adversely affected during the selection of scholarship rewards in the USA, based on such intelligence tests.
Does the IQ test solve the purpose for which it is usually taken?
Even if we assume that there is no ambiguity regarding the accuracy, we still cannot predict the future achievements of a person on the basis of IQ test score. This is simply because a whole lot of factors have their impact upon the life achievements and the way a person would behave in future - which does not come under the scope of ‘intelligence. These may include; God gifted talent, family issues, chronic or prolong illness, a desire to serve humanity or to be rich, a 'passion' for a certain job or field, a sense of responsibility, drug or alcohol abuse, bad company, bad luck or lack of opportunities, sensitivity to the imperfect society causing depression and childhood emotional trauma etc. This gives rise to the debate regarding the usefulness of the test.