Americans’ IQ Scores Are Lower in Some Areas, Higher in One

Summary: While scores for verbal reasoning and matrix reasoning have decreased, scores for spatial reasoning have improved, researchers report.

Source: Northwestern University

IQ scores have substantially increased from 1932 through the 20th century, with differences ranging from three to five IQ points per decade, according to a phenomenon known as the “Flynn effect.”

But a new study from Northwestern University has found evidence of a reverse “Flynn effect” in a large U.S. sample between 2006 and 2018 in every category except one. For the reverse Flynn effect, there were consistent negative slopes for three out of the four cognitive domains.

Ability scores of verbal reasoning (logic, vocabulary), matrix reasoning (visual problem solving, analogies), and letter and number series (computational/mathematical) dropped during the study period, but scores of 3D rotation (spatial reasoning) generally increased from 2011 to 2018, the study found.

Composite ability scores (single scores derived from multiple pieces of information) were also lower for more recent samples. The differences in scores were present regardless of age, education or gender. 

Despite the decline in scores, corresponding study author Elizabeth Dworak said she doesn’t want people to read these findings and think, “Americans are getting less intelligent.”

“It doesn’t mean their mental ability is lower or higher; it’s just a difference in scores that are favoring older or newer samples,” said Dworak, a research assistant professor of medical social sciences at Northwestern University Feinberg School of Medicine.

“It could just be that they’re getting worse at taking tests or specifically worse at taking these kinds of tests.”

The study was published earlier this month in the journal Intelligence

The scientists used the Synthetic Aperture Personality Assessment (SAPA) Project, a free survey-based online personality test that provides test-takers feedback on 27 temperament traits (e.g. adaptability, impulsivity, anxiety, humor) and their ability scores. Thestudy examined survey responses from 394,378 Americans between 2006 to 2018 to examine if cognitive ability scores changed within the U.S. in those 13 years. 

A smaller subset of participants (303,540) was recruited between 2011 and 2018. The 3D rotation data only exists for those who took the survey between 2011 and 2018.

Why the decline in IQ scores?

While the study didn’t examine the reason for the decline in IQ scores, Dworak said there is no shortage of theories in the scientific community, including poor nutrition, worsening health, media exposures and changes to education.

This shows a brain in a lightbulb
Scores of verbal reasoning, matrix reasoning and letter and number series declined; scores of 3D rotation generally increased. Image is in the public domain

“There’s debate about what’s causing it, but not every domain is going down; one of them is going up,” Dworak said. “If all the scores were going in the same direction, you could make a nice little narrative about it, but that’s not the case. We need to do more to dig into it.” 

To that end, Dworak and her colleagues are currently trying to access a dataset that contains 40 years of data to conduct a follow-up study.

A shift in perceived values in society also might have affected scores, Dworak said.

“If you’re thinking about what society cares about and what it’s emphasizing and reinforcing every day, there’s a possibility of that being reflected in performance on an ability test,” Dworak said. 

She gave the example that there’s been more emphasis on STEM education in recent decades, but does that mean other areas, like abstract reasoning, are receiving less attention in schools?

Another factor could be due to a decline in motivation, Dworak said. Because the SAPA Project is advertised as a personality survey, individuals seeking out the test may be more engaged with sections related to measuring temperament and less engaged with sections that are seemingly unrelated to personality.

About this cognition and IQ research news

Author: Kristin Samuelson
Source: Northwestern University
Contact: Kristin Samuelson – Northwestern University
Image: The image is in the public domain

Original Research: Open access.
Looking for Flynn effects in a recent online U.S. adult sample: Examining shifts within the SAPA Project” by Elizabeth Dworak et al. Intelligence


Looking for Flynn effects in a recent online U.S. adult sample: Examining shifts within the SAPA Project

Compared to European countries, research is limited regarding if the Flynn effect, or its reversal, is a current phenomenon in the United States. Though recent research on the United States suggests that a Flynn effect could still be present, or partially present, among child and adolescent samples, few studies have explored differences of cognitive ability scores among US adults.

Thirteen years of cross-sectional data from a subsample of adults (n = 394,378) were obtained from the Synthetic Aperture Personality Assessment Project (SAPA Project) to examine if cognitive ability scores changed within the United States from 2006 to 2018.

Responses to an overlapping set of 35 (collected 2006–2018) and 60 (collected 2011–2018) items from the open-source multiple choice intelligence assessment International Cognitive Ability Resource (ICAR) were used to examine the trends in standardized average composite cognitive ability scores and domain scores of matrix reasoning, letter and number series, verbal reasoning, and three-dimensional rotation.

Composite ability scores from 35 items and domain scores (matrix reasoning; letter and number series) showed a pattern consistent with a reversed Flynn effect from 2006 to 2018 when stratified across age, education, or gender.

Slopes for verbal reasoning scores, however, failed to meet or exceed an annual threshold of |0.02| SD. A reversed Flynn effect was also present from 2011 to 2018 for composite ability scores from 60 items across age, education, and gender.

Despite declining scores across age and demographics in other domains of cognitive ability, three-dimensional rotation scores showed evidence of a Flynn effect with the largest slopes occurring across age stratified regressions.

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  1. So if I’m reading this correctly there are two sunsets of information being used to compare against each other. All of which was measured in the last two decades.

    “Responses to an overlapping set of 35 (collected 2006–2018) and 60 (collected 2011–2018) items”

    I assume the reverse flynn was identified by the younger participants vs older participants to identify the patterns.

    It’s worth exploring the dependency of younger people on automated tasks where originally elder people had to manually think through and do.

    Also since 2000 the entire education system was revamped by Bushes No Child left behind, which effectively made teachers teach for standardized tests instead of the older proven methods. This is further exacerbated by the horrendous common core curriculum implemented by the Obama administration. Both of these initiatives were instituted not to help further our best but to give more support to our worst.

    The success or lack there of seems to be evident. The highest performing people still perform at the same level 1992 vs 2020 students. The lowest performing students groups are what has gotten worse and is bringing down the average. This doesn’t even bring supposed COVID effects that have further eroded performance since the story. Clearly we had declines prior to that.

    The most impacted given the aforementioned study is in the worst performing subsets. This suggests despite all the efforts to remold education for that same subset, it had the opposite effect OR that the root problem got worse. Given USs performance versus many Asian and even European counties in academics has fallen further than it’s peers. This suggests cultural issues that exist within the subset within the United States. A culture that doesn’t invest in children’s development outside of school. A culture that doesn’t prioritize learning.

    So the author makes the argument that you can’t make conclusions based off the data, more research is necessary. When combined with the linked article you can make some connections. This isn’t “Fox News” or Trump or any of that BS as some comments have frivolously asserted. These are kids being measured in the latter linked article. They don’t watch those sources statically. One can easily make counter points to the left about not allowing independent thoughts. They don’t even know what a woman is anymore. There’s plenty of narcissistic idiocy to spread around.

    This is clearly a reflection of environmental, cultural, and educational changes.

  2. Fox News has played a major role in the decline of US IQ scores, steering people away from using critical thinking skills.

  3. Video games can enhance spatial reasoning to the detriment of other areas of intelligence. An overly simplistic solution but there you go!

  4. I see that Jolly Roger is one of those examples of declining verbal reasoning skills, given that he was surprised the study didn’t provide reasons why IQs might have declined despite the article stating that the study didn’t explore the causes of the observations.

  5. “She gave the example that there’s been more emphasis on STEM education in recent decades, but does that mean other areas, like abstract reasoning, are receiving less attention in schools?”…this sentence doesn’t make sense. If a STEM education is not an education in abstract reasoning, what is it?

  6. “free survey-based online personality test” – Seems like this requires follow-up using actual standardized testing.

  7. Jolly Roger, these data mention nothing about “political brain wasting.” Political excuse-making is a popular response from laypeople who have no academic expertise to evaluate research. DNA and evolution are not relevant. Your comment provides an interesting example of presumptuousness.

  8. Wow just a read a whole article on declining iq’s and nowhere did it mention DNA and Genetics, lack of survival of the fittest mechanisms, etc.

    What a joke article. I hope they don’t change this so we can come back to this and laugh at the people who couldn’t reason due to political brain wasting.

    1. You’re truly a perfect example of declining IQ. This is a study of IQ changes decade over decade. Survival of the fittest takes generations to create any meaningful evolutionary change.

    2. Yeah, it’s amazing, the decline in intelligence in evangelicals, conservatives, sovereign citizens, Republicans, Trumpians.

    3. Did you even read the research? Obviously the author of this article didn’t either, but you took to another level of idiocity. It has nothing to do with “declining IQs”, it has to do with a declining RATE or plateauing in the Flynn effect in America — but it noted that this is also beginning to show in regions of Europe as well, the research was just done in America. Why would the article mention genetics and “survival of the fittest”, when the research itself showed the effect is statistically independent of genetic factors? Pray do tell, Roger.

      Anyone with half a brain (not you, evidently) can tell this has to do with the rapid increase in interconnectedness over the past 50-60 years, and naturally that would lead to a growth in the average IQ, but we’ve reached a plateau of interconnectedness where there hasn’t been any revolutionary new technological way to share data and information for about a decade. This correlates directly with the period displaying a plateauing of the Flynn effect in the data, and is a reasonable causal factor — unlike DNA and genetics, which is neither represented by the data nor the population (whatever that would mean for the latter? I love oddly charged implications).

    4. Jolly Roger wow. Were you reading this just to get some of your racial biases confirmed? A broad study including all age groups, and you’re worried about racial intelligence. You don’t even know that DNA and genetics are the same information. Thanks for contributing.

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