Your brain grew rapidly throughout early childhood, when the neuron connections or “synapses” were generated at a prodigious rate and then pruned to adapt to the environment–deleting the synapses that were stimulated the least and increasing those that supported cognitive demands. The next dramatic phase in your brain growth occurred just before puberty when a proliferation of synapses appeared in your prefrontal lobe. This is the part of the brain associated with rational thought and executive function. A late phase in the evolution of the human brain, it provided you with a capacity for problem solving, deductive thinking, and drawing inferences–processes typically described as “higher order thinking skills.”
Psychologist, Jean Piaget discovered in his research that prior to puberty, there are some concepts that are inaccessible to most individuals. The capacity to understand abstract concepts like ratio, proportion and variable at a conceptual level is not available until the brain has developed a particular level of maturity and, for most people, this occurs near puberty. It is during puberty that our brains undergo dramatic changes, not only in cognitive capability, but also in our migration from an egocentric world to a more socially expansive perspective. These brain changes prompted educators to introduce “middle schools,” in which students undergoing these changes were set apart from younger students in elementary schools and the older, more mature, secondary school students. Teaching mathematics to these students was a difficult challenge, because those students who had not yet reached the mental maturation to understand these mathematical concepts had to be taught instrumentally, i.e., by rote procedures.
During puberty, the brain matures in its short-term memory capabilities and in its capacity for abstraction. However, the hormones released during this period broaden an individual’s social interests and this often undermines attention. Students are typically more difficult to teach during this period, because nature’s demands for procreation are competing for their attention.
Throughout this development, we might expect that your IQ would remain relatively stable, because IQ is a measure of intelligence relative to others of the same age. However, recent research indicates that while the average IQ of those in the same age cohort is relatively stable over a span of several years, the IQ of an individual can change significantly during this period. In a longitudinal study, 33 teenagers of average age 14.1 years were administered an IQ test and a structural brain scan in 2004 and then again in 2007, when their average age was 17.7 years. It was found that during this period, the average IQ of the group had changed very little; however about 20% of the participants showed a positive or negative change in IQ of at least 15 points (one standard deviation). Furthermore, magnetic resonance imaging (MRI) revealed that positive changes in IQ corresponded to increased gray matter in sections of the brain associated with those cognitive functions. Summarizing their findings, the researchers reported: (see Ramsden, Sue. et al. 2011. “Verbal and non-verbal intelligence changes in the teenage brain.” Nature. Vol. 479. pp. 113-116.”)
Our results emphasize the possibility that an individual’s intellectual capacity relative to their peers can decrease or increase in the teenage years. This would be encouraging to those whose intellectual potential may improve, and would be a warning that early achievers may not maintain their potential.
Indeed, during the simultaneous processes of rapid neuron growth and pruning that transpires from infancy through adolescence, your brain was in constant flux, changing your personality, your habit of mind and who you are. That’s why the “you” who entered high school is very different from the “you” who will graduate university. Your ideas, beliefs, and manner of thinking will change dramatically through your experiences and intellectual challenges as axons grow, connecting neurons to form a complex network of interconnections. Emerging from adolescence like a butterfly from the pupa, you will come fully equipped with an adult brain–a neural network containing your sense of self, your passions, your instinctive behaviors, your beliefs, and your capacity to learn.
