"IQ scores have been declining in developed countries since the 1990s."
Evidence8
A 2008 Danish conscript study found mean IQ dropped from 101.65 in 1998 to 100.16 in 2003-2004, a decline of about 1.5 points in five years.
Researchers analyzed Danish male conscripts who took the same four cognitive tests at draft board assessments in 1988, 1998, and 2003-2004.
Mean IQ was 101.65 in 1998 and 100.16 in 2003-2004, a drop of about 1.5 points. The decline appeared across all four subtests, showing a downward shift after the late 1990s.
Researchers analyzed Danish male conscripts who took the same four cognitive tests at draft board assessments in 1988, 1998, and 2003-2004.
Mean IQ was 101.65 in 1998 and 100.16 in 2003-2004, a drop of about 1.5 points. The decline appeared across all four...
A 2013 analysis of about 25,000 Finnish male conscripts per year reported IQ gains from 1988-1997 but declines from 1997-2009 averaging 2.0 IQ points per decade across three tests.
The study compiled annual averages for roughly 25,000 Finnish male conscripts ages 18-20 from 1988 to 2009, using Shapes, Number, and Words tests to form an overall IQ score.
Scores rose from 1988-1997 but then declined from 1997-2009 at about 2.0 IQ points per decade across the tests, indicating a sustained drop after the late 1990s.
The study compiled annual averages for roughly 25,000 Finnish male conscripts ages 18-20 from 1988 to 2009, using Shapes, Number, and Words tests to form an overall IQ score.
Scores rose from 1988-1997 but then declined from 1997-2009 at about 2.0 IQ points...
A French comparison of Wechsler Adult Intelligence Scale norms found that Full Scale IQ in 2008-2009 was 3.8 points lower than the 1999 level.
Researchers compared French Wechsler Adult Intelligence Scale norms from 1999 (WAIS-III) with 2008-2009 (WAIS-IV) using 79 adults ages 30-63 who took both versions.
Full Scale IQ in 2008-2009 was 3.8 points lower than the 1999 level, indicating a decline over that decade.
Researchers compared French Wechsler Adult Intelligence Scale norms from 1999 (WAIS-III) with 2008-2009 (WAIS-IV) using 79 adults ages 30-63 who took both versions.
Full Scale IQ in 2008-2009 was 3.8 points lower than the 1999 level, indicating a decline...
A 2018 Norwegian conscription study of 736,808 men born 1962-1991 found IQ rose for earlier cohorts and then turned downward for later cohorts, indicating a post-peak decline.
This study used administrative conscription data for 736,808 Norwegian men from birth cohorts 1962-1991.
Average scores rose for earlier cohorts but turned downward for later cohorts in the series, showing a reversal and subsequent decline rather than continued gains.
This study used administrative conscription data for 736,808 Norwegian men from birth cohorts 1962-1991.
Average scores rose for earlier cohorts but turned downward for later cohorts in the series, showing a reversal and subsequent decline rather than...
A 2018 review projected Nordic conscript trends and reported losses of about 6.99 IQ points for Finland, 6.05 for Denmark, and 6.07 for Norway after the mid-1990s.
The review summarized Nordic conscript trends and projected them onto a common 28-year scale.
It reports projected losses of about 6.99 IQ points for Finland (1997-2009), 6.05 for Denmark (1998-2003.5), and 6.07 for Norway (1993-2002), indicating declines after the mid-1990s.
The review summarized Nordic conscript trends and projected them onto a common 28-year scale.
It reports projected losses of about 6.99 IQ points for Finland (1997-2009), 6.05 for Denmark (1998-2003.5), and 6.07 for Norway (1993-2002), indicating declines...
A 2018 review of UK Raven's matrices trends found that 14-year-olds showed a net loss of about 2.26 IQ points from 1980 to 2008.
The review analyzed UK Raven's Progressive Matrices trends by age from 1980 to 2008.
For 14-year-olds, the reported trend was a net loss of about 2.26 IQ points over the period, indicating lower scores in the late 2000s than in 1980.
The review analyzed UK Raven's Progressive Matrices trends by age from 1980 to 2008.
For 14-year-olds, the reported trend was a net loss of about 2.26 IQ points over the period, indicating lower scores in the late 2000s than in 1980.
A 2015 meta-analysis of 96 samples (13,172 people) on a spatial perception test in German-speaking countries found an inverse U-shaped trend with later cohorts scoring lower.
A cross-temporal meta-analysis combined 96 samples (13,172 people) from German-speaking countries on the three-dimensional cubes spatial perception test from 1977 to 2014.
The trajectory was inverse U-shaped: scores rose early and then fell in later cohorts, with the later period showing lower spatial-test performance.
A cross-temporal meta-analysis combined 96 samples (13,172 people) from German-speaking countries on the three-dimensional cubes spatial perception test from 1977 to 2014.
The trajectory was inverse U-shaped: scores rose early and then fell in later...
A 2016 systematic review found 9 studies across 7 countries with evidence of a negative Flynn effect, with the strongest large-sample evidence coming from Norway, Denmark, and Finland.
A systematic literature review searched for studies reporting a negative Flynn effect and applied strict inclusion criteria.
It identified 9 articles across 7 countries and emphasized that the strongest evidence came from Norway, Denmark, and Finland where near-population conscript data showed declines in general ability over at least five years.
A systematic literature review searched for studies reporting a negative Flynn effect and applied strict inclusion criteria.
It identified 9 articles across 7 countries and emphasized that the strongest evidence came from Norway, Denmark, and Finland where...