In the 20th Century, the average IQ rose, in a phenomenon known as the Flynn Effect. But over the last 15 years, the trend has reversed, and people are getting dumber.

A Spring 2023 study indicates that, for the first time in a century, Americans’ average IQ is falling. The academics who conducted the study hypothesize that a declining quality of education may be reversing the IQ gains experienced by earlier generations.

The recent study, published in the journal Intelligence, measures IQ test results among 18- to 60-year-olds to examine the inversion of the phenomenon first described by philosopher James Flynn.