Platt Jonathan M, Keyes Katherine M, McLaughlin Katie A, Kaufman Alan S
Department of Epidemiology, Mailman School of Public Health, Columbia University, 722 West 168 Street, New York, NY 10032.
Center for Research on Society and Health, Universidad Mayor, Santiago, Chile.
Intelligence. 2019 Nov-Dec;77. doi: 10.1016/j.intell.2019.101385. Epub 2019 Sep 10.
Generational changes in IQ (the Flynn Effect) have been extensively researched and debated. Within the US, gains of 3 points per decade have been accepted as consistent across age and ability level, suggesting that tests with outdated norms yield spuriously high IQs. However, findings are generally based on small samples, have not been validated across ability levels, and conflict with reverse effects recently identified in Scandinavia and other countries. Using a well-validated measure of fluid intelligence, we investigated the Flynn Effect by comparing scores normed in 1989 and 2003, among a representative sample of American adolescents ages 13-18 (n=10,073). Additionally, we examined Flynn Effect variation by age, sex, ability level, parental age, and SES. Adjusted mean IQ differences per decade were calculated using generalized linear models. Overall the Flynn Effect was not significant; however, effects varied substantially by age and ability level. IQs increased 2.3 points at age 13 (95% CI=2.0, 2.7), but decreased 1.6 points at age 18 (95% CI=-2.1, -1.2). IQs decreased 4.9 points for those with IQ<70 (95% CI=-4.9, -4.8), but increased 3.5 points among those with IQ>130 (95% CI=3.4, 3.6). The Flynn Effect was not meaningfully related to other background variables. Using the largest sample of US adolescent IQs to date, we demonstrate significant heterogeneity in fluid IQ changes over time. Reverse Flynn Effects at age 18 are consistent with previous data, and those with lower ability levels are exhibiting worsening IQ over time. Findings by age and ability level challenge generalizing IQ trends throughout the general population.
智商的代际变化（弗林效应）已得到广泛研究和讨论。在美国，每十年智商增长3分被认为在不同年龄和能力水平上是一致的，这表明使用过时常模的测试会得出虚假的高智商分数。然而，这些发现通常基于小样本，未在不同能力水平上得到验证，并且与最近在斯堪的纳维亚半岛和其他国家发现的反向效应相矛盾。我们使用一种经过充分验证的流体智力测量方法，通过比较1989年和2003年标准化的分数，对13至18岁的美国青少年代表性样本（n = 10,073）进行了弗林效应研究。此外，我们还研究了弗林效应在年龄、性别、能力水平、父母年龄和社会经济地位方面的差异。使用广义线性模型计算每十年调整后的平均智商差异。总体而言，弗林效应并不显著；然而，效应在年龄和能力水平上有很大差异。13岁时智商增加2.3分（95%置信区间 = 2.0, 2.7），但18岁时下降1.6分（95%置信区间 = -2.1, -1.2）。智商低于70的人智商下降4.9分（95%置信区间 = -4.9, -4.8），但智商高于130的人智商增加3.5分（95%置信区间 = 3.4, 3.6）。弗林效应与其他背景变量没有显著关联。我们使用了迄今为止最大的美国青少年智商样本，证明了流体智商随时间变化存在显著的异质性。18岁时的反向弗林效应与先前数据一致，能力水平较低的人智商随时间呈恶化趋势。按年龄和能力水平得出的研究结果对推断整个人口的智商趋势提出了挑战。
