Cross-temporal meta-analysis of Trail Making Test performance (1953-2024): A Flynn effect for executive functioning

Cross-temporal intelligence test score changes (the Flynn effect) exhibit domain- and country-specific change trajectories. Process overlap theory suggests that positive intelligence subtest intercorrelations—the positive manifold of intelligence—may be due to executive functioning playing an important role in the performance on all intelligence subdomains. This may mean that changes in executive functioning may be (partly) responsible for observed test score changes in the vein of the Flynn effect. However, change trajectories of executive functioning have so far remained largely unexplored. In a preregistered cross-temporal meta-analysis, we investigated general population changes of trail making test (TMT) performance, a well-established and widely-used test instrument for assessing executive functioning. We identified all available records reporting mean TMT performance from the available literature and predicted TMT outcome measures by data collection year in precision-weighted linear and multiple regressions. Analyzing a large dataset based on 8,000+ studies (k = 16,000+; N = 1,000,000+) published between 1946 and 2025, we show global TMT score increases. Gains in patient samples were more pronounced than gains in healthy samples. Change trajectories were generalized across different TMT outcome measures but were differentiated according to country of data collection. Our findings indicate that executive functioning changes may likely be linked to the Flynn effect in standard domains of cognitive task performance.