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Researchers at UConn and the University of Minnesota have discovered that there may be more to the "summer slide" phenomenon following a break in schooling than just forgetting material. In fact, the researchers found reliable patterns of seasonal variation in performance on laboratory tests assessing more general cognitive abilities like executive functioning, with lowest scores consistently found in the summer months.

Arielle Keller, a UConn assistant professor of cognitive neuroscience and member of UConn’s Institute for Brain and Cognitive Sciences, and Bart Larsen, a neuroscientist and assistant professor of pediatrics at the University of Minnesota who co-directs translational research at the Masonic Institute for the Developing Brain, collaborated on the study. Their paper, "Cognition Varies Across the Calendar Year in Multiple Large-Scale Datasets," was published in the Proceedings of the National Academy of Sciences.

Patterns in cognitive test performance

Analyzing data from laboratory-based cognitive tests from more than 23,000 children and young adults, the study concluded that performance on tests may be dependent on the timing of the assessments. The researchers explored a potential source of test score variation—colloquially referred to as the "summer slide"—to determine whether poorer performance follows an extended break from school, such as a summer vacation.

School-aged children in the U.S. consistently performed slightly worse on cognitive tests when taken in the late summer, following a break from school. Similarly, students in Singapore had poorer test performance on assessments given in February.

The school break in that country typically occurs from November to January, so student performance slipped in a likewise fashion to American students. This dip in performance was only observed in school-age youth and was not observed in young-adults.

Whereas prior studies have reported a "summer slide" in performance on academic tests, such as in math or science, this study focused on laboratory-based cognitive tests that assessed more general skills, such as executive functioning. Results were consistent across four diverse datasets of children across the U.S. and in Singapore.

Socioeconomic factors and broader implications

"Remarkably, these findings suggest that the summer slide is not simply about forgetting material that was learned in the preceding academic year," Keller says. "Given that psychology has historically struggled with the ‘reproducibility crisis’ where key findings often fail to replicate across diverse samples, this level of consistent replication in our findings lends strong credence to our results."

Additionally, the researchers showed that the summer slide is observed across children from different socioeconomic backgrounds and was consistent in kids both with and without ADHD. The researchers also took care to provide context for their results, highlighting the well-documented effect that socioeconomic inequality is also significantly associated with cognitive performance.

"The effect of disparities in socioeconomic context on cognitive performance are seven times bigger than the effect of the summer slide," Keller says. "Thus, to support healthy cognitive development in children, we should be directing less attention and resources to the summer slide and more attention and resources toward policies that reduce socioeconomic inequality."

Considerations for research and future study

The researchers also concluded that children in research studies might be evaluated unfairly based on the calendar. A child tested in September may not seem as intelligent as the same student when assessed in the spring.

"This is a crucial wake-up call for how scientific studies are designed," says Larsen. "We also found that there’s a systematic bias in when children from lower socioeconomic backgrounds are brought in for research studies."

While the study drew a connection between the summer slide and dipped performance, the researchers advise that there is no reason for panic or to rethink the academic calendar.

"It is important to emphasize that while the effect is consistent, it is small," Keller says. "The impact of a child’s environment is seven times larger than this seasonal dip, and improvements in cognitive abilities that come naturally with adolescent development vastly outweigh it."

This study motivates future work to investigate what might be going on during the summer slide, including the potential benefits of summer vacation for other aspects of physiological, social, or long-term cognitive development.

More information: Arielle S. Keller et al, Cognition varies across the calendar year in multiple large-scale datasets, Proceedings of the National Academy of Sciences (2025). DOI: 10.1073/pnas.2506054122

Citation: Long school breaks tied to dip in cognitive test performance (2026, January 8) retrieved 8 January 2026 from https://phys.org/news/2026-01-school-dip-cognitive.html

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