In the early 20th Century, statisticians and psychologists began attempting to quantify the idea of intelligence. Through a series and iterations of various tests and experiments, the term “Intelligence Quotient” was coined in an attempt to assign a number to one’s intellectual ability.
During World War I, the government used various measures to “test” recruits to determine which tasks they were best suited. At this time the rise of IQ testing took off, and it is now used in many industries. In fact, an entire branch of psychology called Industrial and Organization Psychology (I&O) is dedicated to providing such services.
But getting back to how IQ relates to kids in modern day schooling, we have to consider IQ in context of the adolescent brain.
In the early 1940s, psychologist Raymond Cattell introduces a very interesting (and important) take on IQ. He proposed there are two types of cognitive abilities:
Crystallized Intelligence refers to the knowledge, facts, and words we acquire in certain settings over a lifetime. Research consistently shows that crystallized intelligence can change over time.
Fluid Intelligence refers to the ability to think about ideas and draw reasonable inferences and conclusions. Research is inconsistent on whether fluid intelligence can change; however, most experts agree that it is relatively unchanged over time.
Although research has pushed Cattell’s theory to new levels, the same basic tenets exist in relation to school today. Students in school are expected to memorize facts, words, dates, etc., to which their success is directly tied to their crystallized intelligence.
However, the ability to think critically, understand abstract concepts, and interact with peers and teachers in an appropriate manner has mostly to do with their crystallized intelligence.
So, let’s look at the questions:
Can My IQ Change?
If we look solely at Cattell’s model, then the answer is SORT OF. While fluid intelligence seems to be stable over time, our crystallized intelligence can (and usually does) increase over time as we learn more and more facts in school.
But, as I mentioned previously, Cattrell’s model has evolved quite a bit since the 1940s. Today there are numerous tests that claim they reliably assess intelligence. However, there are two tests that are widely used in clinical settings: the Wechsler scale and the Woodcock-Johnson. Both of these tests are valid and reliable and provide a numerical value for the individuals’ overall cognitive and intellectual ability.
But can that numerical value change over time? Well, unfortunately the answer is MAYBE.
Looking at the research, it is very inconclusive whether IQ actually changes over one’s lifetime. However, what does appear nearly universal is that IQ is less prone to change the older one gets. That is, children and adolescents may see the most fluctuation in IQ compared to adults. And frustratingly, there appears to be little evidence to explain these fluctuations.
In my personal experience, based on students I have tested and based on data I have seen, it appears IQ is more fixed than it is prone to change. It is not uncommon for me to test a child twice and see similar intelligence data across both tests, even though they were several years apart. This suggests that despite an increase in crystallized knowledge, students overall intelligence is unchanged.
The big take away from all this is that overall intelligence does not necessarily impact one’s ability to utilize crystallized intelligence. And crystallized intelligence is a major factor in academic success. So good news…if your child is struggling with a lower-than-expected IQ, it does not necessarily mean he or she cannot be successful in school. And we can thank Cattrell for that!