Verbal and non-verbal intelligence changes in the teenage brain

 
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An individual’s capacity to learn is often treated as static across his or her lifetime.  Studies that identify changes in IQ (a widely used, standardized measure of intellectual abilities) are generally unable to attribute that change to a real increase or decrease in intelligence as opposed to measurement error in testing, and much of the variation in IQ remains unexplained.

A 2011 study in the international weekly journal of science Nature, “Verbal and Non-Verbal Intelligence Changes in the Teenage Brain,” investigates whether structural changes in the brain and longitudinal changes in IQ are related.  The scientists studied 33 healthy and neurologically normal adolescents with a wide range of abilities, first testing them in 2004 at ages 12 to 16, then again in 2007/2008 at ages 15 to 20.

Key findings from the study include:

  • Verbal and non-verbal (performance) IQ can rise or fall in the teenage years, and these fluctuations are correlated with structural changes in gray matter in the areas of the brain associated with speech and finger movements, respectively.  These structural changes suggest that IQ fluctuations are not solely due to measurement error.
  • In a composite measure of verbal and performance IQ, one-third of participants experienced a clear change in measured intelligence, with the largest gain being 21 points and the largest decrease 18 points.
  • Gray matter changes associated with verbal and performance IQ do not correspond to the region of the brain associated with general intelligence (the g factor), indicating that general intelligence may remain relatively constant while verbal and performance IQ fluctuate due to changes in sensorimotor skills.

These findings may “be encouraging to those whose intellectual potential may improve, and … a warning that early achievers may not maintain their potential.”  In either case, the study suggests it would be unwise to treat teenagers as if their intelligence is preordained by their IQ scores.  It is still unknown if this brain plasticity extends into adulthood, and further research is needed to determine the causes of these fluctuations and their effects on educational performance and employment prospects.

In related research, scholars in Norway produced similar findings in their 2011 study, “Schooling in Adolescence Raises IQ Scores.” They found that increasing the number of years of compulsory schooling for students had a “substantial effect on IQ scores measured” at age 19.

Tags: children, youth, cognition

    Writer: | Last updated: November 15, 2011

     

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