IQ scores significantly increased from 1932 through the 20th century all over the world, with differences ranging from roughly three to five IQ points per decade. This phenomenon is known as the “Flynn Effect.” Now, however, a new study out Northwestern University suggests a “reverse-Flynn Effect” of sorts may be taking place in the United States.
This reverse-Flynn Effect was present across a large U.S. sample covering between 2006 and 2018 in every category — except one. Still, there were consistent negative slopes among three out of four cognitive domains.
Ability scores pertaining to verbal reasoning (logic, vocabulary), matrix reasoning (visual problem solving, analogies), and letter and number series (computational/mathematical) all dropped over the course of the study period. However, scores of 3D rotation (spatial reasoning) generally increased between 2011 to 2018.
Composite ability scores (single scores derived from multiple pieces of information) were also lower across the more recent samples. These score differences persisted regardless of age, education, or gender.
If you’re curious to delve deeper into the topic, read more about it here.