Long School Breaks Are Linked to a Dip in Cognitive Test Performance
Researchers from the University of Connecticut (UConn) and the University of Minnesota have found compelling evidence that long breaks from school are associated with small but consistent drops in children’s cognitive test performance. The findings suggest that the well-known “summer slide” may involve more than simply forgetting academic material—it may also reflect broader changes in how children perform on general cognitive tasks.
The study, led by Arielle Keller, an assistant professor of cognitive neuroscience at UConn, and Bart Larsen, a neuroscientist and assistant professor of pediatrics at the University of Minnesota, examined whether the timing of cognitive assessments across the calendar year influences performance. Their research paper, titled “Cognition Varies Across the Calendar Year in Multiple Large-Scale Datasets,” was published in the journal Proceedings of the National Academy of Sciences.
Looking Beyond Academic Forgetting
For years, educators and researchers have used the term summer slide to describe declines in academic performance—particularly in areas like math and reading—that appear after students return from summer vacation. Most explanations have focused on the idea that students simply forget what they learned during the school year.
This new research takes a different angle. Instead of academic tests tied directly to school curricula, the researchers focused on laboratory-based cognitive tests that measure more general mental abilities. These included aspects of executive functioning, such as attention control, working memory, and cognitive flexibility—skills that support learning across many domains.
By shifting the focus away from school subjects and toward general cognition, the researchers were able to ask a broader question: does time away from structured schooling affect how children perform on cognitive tasks overall?
A Massive Dataset Across Countries
To answer this question, Keller and Larsen analyzed data from more than 23,000 children and young adults. The data came from four large-scale datasets, covering participants from across the United States as well as Singapore. This wide scope allowed the researchers to look for consistent patterns rather than isolated effects tied to a single group or region.
One of the most striking findings was that school-aged children in the U.S. consistently performed slightly worse on cognitive tests administered in late summer—the period immediately following the long summer break. Importantly, this pattern showed up across multiple datasets, lending strength to the conclusion that the effect is real and reliable.
The international comparison added another layer of evidence. In Singapore, where the main school break typically runs from November to January, students showed poorer cognitive test performance on assessments given in February. In other words, the dip appeared after the major school break, regardless of when that break occurred in the calendar year.
This parallel pattern strongly suggests that the effect is tied to time away from school, not to summer itself.
Who Is Affected—and Who Is Not
The researchers found that this seasonal dip in cognitive performance was limited to school-age children. When they looked at young adults, the pattern disappeared. This distinction is important because it points toward schooling—and not age alone—as a key factor.
The effect was also remarkably consistent across different groups of children. It appeared in children from a wide range of socioeconomic backgrounds and was present in children both with and without ADHD. This consistency strengthens the argument that the phenomenon reflects a general pattern rather than something driven by a specific subgroup.
At the same time, the researchers were careful to put the findings in perspective.
How Big Is the Effect?
While the seasonal variation in cognitive test scores was consistent, it was also small in size. Keller emphasized that the impact of a child’s socioeconomic environment on cognitive performance is far larger—about seven times greater than the effect associated with school breaks.
In other words, while timing matters, it matters much less than broader factors like access to resources, educational opportunities, and stable living conditions. The researchers stress that concerns about the summer slide should not distract from efforts to address socioeconomic inequality, which has a much stronger and more lasting influence on cognitive development.
They also note that normal developmental gains during adolescence far outweigh the temporary seasonal dip observed in the study.
Implications for Research and Testing
One of the most important takeaways from the study relates to how cognitive research is conducted. Because performance varies across the calendar year, the timing of assessments can introduce bias.
A child tested in early fall may appear to perform worse than the same child tested in spring—even if their underlying cognitive abilities have not changed. This has serious implications for research studies that compare groups of children tested at different times of year.
The researchers also found evidence of systematic bias in when children from lower socioeconomic backgrounds are brought in for research studies, raising concerns about fairness and representativeness in scientific data collection.
These findings serve as a reminder that calendar timing is not a neutral factor and should be carefully considered when designing studies and interpreting results.
No Need to Panic About the School Calendar
Despite the clear patterns observed, the researchers are careful not to overstate the implications. They emphasize that the effect is consistent but modest, and there is no reason to rethink the academic calendar or view summer breaks as harmful.
In fact, time away from school may offer important benefits that were not measured in this study, such as improvements in physical health, social development, family bonding, and long-term well-being. The researchers suggest that future studies should explore what is happening during school breaks that leads to these short-term cognitive changes—and whether some aspects of time off may actually be beneficial.
Understanding Executive Function and Seasonal Changes
Executive functioning plays a crucial role in learning and everyday decision-making. Skills like focusing attention, managing impulses, and switching between tasks are shaped by both biological development and environmental structure.
School provides a highly structured environment with regular schedules, cognitive demands, and social expectations. When that structure disappears for an extended period, it may temporarily affect how efficiently these skills are engaged. Seasonal factors such as changes in sleep patterns, daily routines, physical activity, and screen time may also contribute.
Importantly, the study does not claim to identify the exact mechanisms behind the observed dip—it simply shows that the pattern exists across large, diverse populations.
A Broader Perspective on the “Summer Slide”
This research adds a new layer to the ongoing conversation about learning loss and school breaks. It suggests that the summer slide is not just about academics, but may reflect broader shifts in cognitive performance tied to changes in daily structure and routine.
At the same time, it reinforces a crucial message: short-term seasonal effects are minor compared to the powerful role of environment and inequality. Supporting healthy cognitive development means focusing on long-term conditions that shape children’s lives, not just what happens during a few months of the year.
Research paper: https://doi.org/10.1073/pnas.2506054122
