The “Use It or Lose It” Effect: Research Reveals That IQ Can Fluctuate

Though we rely on our intelligence every day, the exact nature of intelligence remains poorly understood. Researchers are unsure of how to best define intelligence and how many different “types” of intelligence there might be. There’s also been a great deal of debate over the plasticity of the mind. In the past, most people assumed that one’s level of intelligence was written in stone at birth. Over the last decade, however, some researchers have argued that nothing could be further from the truth—that instead, intelligence is shaped largely by environmental factors. It can be nurtured, changed, and increased with the correct stimulation, they claim, especially in the first years of life. In their view, barring the presence of a developmental disorder, every child has the potential to become a genius, or at least very bright.

Naturally, many parents have latched onto this idea. We all want to believe that with the right strategies, we can give our children the intellectual tools they need to survive and thrive. This is especially true for many parents in low-income households. They know that intelligence and economic prosperity are linked, so they hope that by improving the quality of their child’s education and providing a fertile environment for intellectual growth at home, they can secure a better quality of life for their child. Governments have also gotten on board with this idea. Substantial resources have been invested into programs aimed at improving the intellectual lives of underprivileged kids. The Head Start program in the United States, for example, focuses on giving low-income children the education, nutrition, and medical care they need to thrive. The experts behind these programs feel that by raising IQs, they can lower poverty rates and mitigate the consequence of racial and economic disparities… But is there any evidence to support the idea that intelligence can be increased?

Programs like Head Start would, of course, be valuable regardless of whether or not they can increase participants’ Intelligence Quotient. Giving children from low-income households the care they need reduces the rate of both illness and criminality. This in turn gives kids a strong foundation on which to build a career and eventually start a family of their own. With that being said, research into the effectiveness of these programs has revealed something interesting about human intelligence: Just like it can be increased with stimulation, it can also “fade out” in the absence of sufficient stimulation.

The fact that social programs can increase a child’s IQ has been demonstrated in multiple studies. However, recent research also suggests that this effect may be surprisingly temporary: Participants’ IQs rise while they’re enrolled in programs like Head Start, but once they leave these programs, their IQs slowly begin to decline. (It’s important to note that these findings are still being investigated; the purported drop in IQ may be related to different testing approaches or flaws in the studies themselves.) In particular, a study published in December 2015 lent credence to the existence of the “fade out” effect. This large-scale study looked at 7,584 children in a series of 39 randomized controlled trials and appeared to confirm that IQ does indeed decline—not drastically, but measurably—once kids are released from supportive programs.

These findings can be interpreted in several different ways: Those who favour a genetic theory of intelligence claim that this tendency to “backslide” shows that kids inevitably return to the level of intelligence predetermined by their genes. Those who prefer an environmental theory of intellectual development believe that these fluctuations reveal that if we don’t actively use our intelligence, we can lose at least some of it. Just like we have to exercise regularly to keep our muscles, hearts, and lungs in top condition, we have to proactively keep our brains fit, too. Finally, a third cohort feels that these programs cannot prove anything about the nature of intelligence as they only train children to perform better on IQ tests… Which are considered by many to be a poor way of measuring intelligence in the first place.

For the time being, the exact mechanisms behind the “fade out” effect remain a mystery. As such, it’s impossible to ascertain whether or not it indicates that intelligence is genetically predetermined. In the meantime, however, these observations do raise some important questions: How do we stop kids, especially kids in low-income households, from falling through the cracks during adolescence and early adulthood? How do we inspire kids to seek out intellectual stimulation on their own, so that they remain lifelong learners? Are IQ tests even still relevant, and if not, how do we update our social programs to nurture individual learning styles (rather than training kids to perform better on a single standardized test)? Can a child’s learning style change over time, and how do we adapt to that change? Until we have a more accurate, useful way of measuring of intelligence, our efforts to increase it will probably fall short.

For parents, the best approach to the issue of intelligence is generally to maintain realistic expectations. Creating the right conditions for intellectual growth certainly won’t harm your child—and it may very well help him or her—but you should accept the possibility that genetics also play a significant role in the development of intelligence. Rather than trying strictly to raise your child’s IQ, you should focus on enriching their imagination, enhancing self-awareness, and creating a strong connection between you both. Doing the aforementioned will help your child grow into a stable, well-rounded adult who is able to make use of any opportunities that come her way.


Author: Rachel Cohen

This is a guest post by Toronto psychotherapist Rachel Cohen. Rachel is very knowledgeable in giftedness, after completing her Master’s Degree in Psychology at the University of Nevada, she worked for 3 years at the Davidson Academy for Gifted Children. You can follow Rachel on Twitter at @RachiieCohen


Article reviewed by Dr. Tali Shenfield on April 29, 2021

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