This paper discusses the co-occurrence model and its associated research program, and it argues that the model provides the best supported theory of secular changes in cognitive ability. The co-occurrence model offers a better solution to Cattell's paradox (relative to the alternatives in the literature), and it is able to accommodate Flynn's four major paradoxes also. A review of empirical work conducted in order to test the model's predictions demonstrates that many populations in which selection favors lower intelligence have experienced a decline in g or some cognitive ability variable that correlates with g, at the same time that average phenotypic IQ has increased. Moreover, since the co-occurrence model makes predictions about variables that are not directly concerned with cognitive ability testing, its research program can be extended to other domains of research.

本文讨论了共现模型及其相关研究计划，并认为该模型为认知能力的长期变化提供了最好的支持理论。共现模型为 Cattell 悖论（相对于文献中的替代方案）提供了更好的解决方案，并且它也能够适应 Flynn 的四个主要悖论。为检验模型的预测而进行的实证工作回顾表明，许多选择倾向于低智力的人群经历了g或与g相关的某些认知能力变量的下降，同时平均表型智商有所增加。此外，由于共现模型对与认知能力测试不直接相关的变量进行预测，因此其研究计划可以扩展到其他研究领域。