We’re getting smarter.  Literally.  IQ test raw scores have been generally increasing every generation. Each generation is about 9 – 15 IQ points brighter than the one before it.  If we set the current average IQ at 100, then the average IQ of 1900 was about 60. IQ scores are scaled with the median set to 100. So, the scores don’t change over time, but rather as intelligence has increased, the IQ tests become more challenging and are scored differently.  Another way to look at it is that whatever you get on a current IQ test, you’d likely get a higher score if you took an older version against an older population for reference. This tendency for IQ raw scores to increase over time is called the “Flynn Effect.”

What is going on? There are a few theories.

IQ tests are a measure of cognitive ability because intelligence cannot be directly measured.  Younger generations are performing much better than their ancestors on parts of the IQ test dealing with patterns, spatial relations, and similarities. To the contrary, there has been little gain in arithmetic and vocabulary.

Experts posit that as a species our basic intelligence has not increased, but our cognitive abilities have improved. This is somewhat of a paradox but can be explained by how our society has evolved over time and how that has affected the way we think, which, in turn, has affected our IQ scores.

Improvements in cognitive abilities stem from the move in the developed world towards many more years of education and a society and culture that immerses people more into situations that develop cognitive ability thru exposure to the abstract.

For example, many more people work in professional roles which enhance the ability to be innovative and think abstractly. Video games enhance our ability to problem solve in visual and symbolic contexts.  TV programs now weave together complex plots and many characters.  Compare 24 or Game of Thrones to I Love Lucy or Starsky and Hutch.  From a young age we now train our brains to think and process information differently than our ancestors.  This leads to greater cognitive and abstract reasoning ability, which, in turn, leads to higher IQ scores.  How we think actually changes the structure of our brains.

The rise of technology and urban living has led to us living lives that are much more rooted in the abstract.

For example, a question on an IQ test that asked “what is similiar about dogs and rabbits” might be answered as follows in the early 1900s:  “dogs are used to hunt rabbits.”. A modern child would likely answer: “they are both mammals.” the latter answer would add to a higher IQ score.  The former answer is much more practical to a boy in 1910.

Abstract reasoning ability doesn’t necessarily mean that we perform better intellectually or are less gullible.  Belief in the paranormal is as high as ever.  A huge percentage of the population believes in UFOs and an embarrassingly high number of people believe in astrology.  A large percentage of Americans don’t believe evolution occurred despite overwhelming evidence to the contrary.  The rise in the ability to think in the abstract can be used to defend nonsense rather than make intellectual gains.

A few other theories of why IQ scores have increased over time include better worldwide nutrition, and increases in education.