It is generally assumed that everyone has a stable IQ (intelligence quotient) score, thereby making it a standard measure of intelligence for teenagers everywhere. Those who perform badly in IQ tests as teenagers are written off as being unable to do as well in future endeavors, like getting into a highly ranked college or finding a job. Those who do well in such tests can get complacent, believing that they are "naturally smart" and are destined to do well.
However, new research has found that IQ is not a stable a trait as was previously believed. Using IQ tests taken from a group of 33 adolescents when they were between the ages of 12 and 16 and then again four years later when the same adolescents were between 15 and 20 years old, researchers have found that there were significant changes in their scores from 2008 compared to the scores from 2004.
Changes were up to a 20 point increase or decrease in scores, whether it was in verbal (language, math, knowledge and memory) or non-verbal (visual puzzles, identifying missing pieces of a picture) types of IQ. Changes to one type of IQ did not appear to cause a change in the other type.
Along with comparing IQ scores, researchers also looked at MRI (magnetic resonance imaging) scans of the subjects brains. They found that the increase in scores correlated with increases in grey matter of the brain.
Grey matter is where processing takes place in the brain, so it makes sense that increased intelligence would correlate with increased information processing. Specifically, increased verbal IQ scores correlated with increased density of grey matter in the part of the brain which is activated during speech, and increased non-verbal IQ scores correlated with the part of the brain activated during hand movements. It was not clear whether decreases in IQ scores meant a decrease in grey matter in the relevant areas of the brain.
So what does this mean? This research shows that intelligence is still developing in children, and that having a low IQ score during the pre-teen years doesn't necessarily mean anything later on. It also shows that students who have a high IQ score earlier in life may not have the same score later, so they have to keep working hard and studying.
This last point especially is supported by research which has also found that the brain doesn't lose its plasticity — its ability to mold itself and change with the amount and type of input it is receiving and the environment it is in — even when people are adults. For example, Professor Eleanor Maguire from the Wellcome Trust Centre found that taxi drivers in London have increased volume in their hippocampus, an area of the brain which controls memory and navigation.
Further research will be needed to decide whether or not this finding can be generalized to IQ changes even as adults, and whether these results also apply to other cognitive functions. Research can also be done to determine why these changes are happening and if it's really just as simple as "working out" that part of your brain more or less. Research on these changes may have long-lasting impacts on education, employment, and how the education system is structured in the future. Furthermore, this research could be applied to mental disorders and whether changes in supposedly "stable" traits like IQ could contribute to such disorders.
Clearly, people's brains don't stop changing as they grow older, and this applies to no other group more distinctly than teenagers. Their brains are still changing and molding dramatically, even more so than adults' brains, and intelligence is something that can be molded along with practical and physical skills. Brains are made to adapt to situations, and if one stops trying to study and better himself or herself, his or her brain might simply stop trying to keep up.
