American IQ Test Scores Show Recent Declines, According To New Study

Excerpt from Forbes:

American IQ test scores have dropped during a recent 13-year period, a remarkable finding that runs counter to the well-established trend of increasing IQ scores throughout much of the 20th century.

That’s a main result reported in a new study published in the journal Intelligence, entitled Looking for Flynn effects in a recent online U.S. adult sample: Examining shifts within the SAPA Project by Elizabeth M. Dworak, William Revelle, and David M. Condon.

The study found evidence of a reverse “Flynn effect” in a large U.S. sample of almost 400,000 individuals tested between 2006 and 2018 in several ability areas. The Flynn effect refers to the well-replicated finding that IQ scores increased consistently through much of the 20th century, with increases ranging from three to five IQ points per decade.

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Why The Decrease?

The study does not answer the question of why the decline in IQ scores was observed during this period. “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.”

Possible explanations for the downward direction include a shift in educational practices and emphases, a biased sample of adults who responded to the online SAPA instrument, differences in motivation among people taking this test versus those who are tested for different reasons, and differences between this instrument and the standard IQ tests used in other research.