Generational intelligence test score gains over large parts of the 20th century have been observed to be negatively associated with psychometric g. Recent reports about changes in the cross-temporal IQ trajectory suggest that ability differentiation may be responsible for both changes in g as well as increasingly (sub)domain specific and inconsistent trajectories. Schooling is considered to be a main candidate cause for the Flynn effect, which suggests that school achievement might be expected to show similar cross-temporal developments. In the present study, we investigated evidence for cross-temporal changes in achievement-based g in a formal large-scale student assessment in Italy (i.e., the INVALSI assessment; N = 1,900,000). Based on data of four school grades (i.e., grades 2, 5, 8, and 10) over 13 years (2010-2022), we observed little evidence for changes in achievement g in general. However, cross-temporal trajectories were differentiated according to school grade, indicating cross-temporal g decreases for lower grade students whilst changes for higher grade students were positive. These findings may be interpreted as tentative evidence for age-dependent achievement-g differentiation. The presently observed achievement g trajectory appears to be consistent with recently observed evidence for a potential stagnation or reversal of cognitive test score gains.

翻译：在20世纪的大部分时间里，代际智力测验分数的增长被观察到与心理测量学中的g因子呈负相关。近期关于跨时间IQ轨迹变化的报告表明，能力分化可能是导致g因子变化以及日益增强的（子）领域特异性和不一致轨迹的原因。学校教育被认为是弗林效应的主要候选原因，这意味着学业成就可能表现出类似的跨时间发展。在本研究中，我们基于意大利一项大规模正式学生评估（即INVALSI评估；样本量N=1,900,000），探讨了基于成就的g因子跨时间变化的证据。利用13年（2010-2022年）间四个年级（即2、5、8和10年级）的数据，我们总体上观察到成就g因子变化证据不足。然而，跨时间轨迹因年级而异，低年级学生的g因子随时间呈下降趋势，而高年级学生的变化则为正值。这些发现可被解释为年龄依赖性成就g分化的初步证据。本研究中观察到的成就g轨迹与近期关于认知测验分数增长可能停滞或逆转的发现一致。