Cognition varies across the calendar year in multiple large-scale datasets

Area of Science:

• Cognitive psychology
• Developmental psychology
• Educational psychology

Background:

• Children's cognitive abilities fluctuate across timescales, including seasonal variations like the
• summer slide,
• characterized by academic performance decreases post-vacation.
• The generalizability of the summer slide across different assessments and its impact on diverse sociodemographic groups remain debated.
• Previous research often attributes seasonal cognitive changes to forgetting, with limited large-scale studies examining general cognitive skills in youth versus adults.

Purpose of the Study:

• To systematically investigate seasonal variation in general cognitive skills using standardized laboratory assessments in school-age children and compare it to young adults.
• To quantify the cyclical, seasonal variation in cognitive performance across diverse datasets, accounting for geographic, demographic, and measurement variations.
• To determine if cognitive performance minima align with school vacation periods in children.

Main Methods:

• Utilized four large datasets (total n = 23,251) with variations in geography, demographics, mental health, and measurement.
• Employed generalized additive models with cyclic cubic splines to analyze cyclical, seasonal variation in cognitive performance.
• Compared cognitive performance patterns between school-age children and young adults.

Main Results:

• School-age children, but not young adults, exhibited consistent minima in cognitive performance following school vacations (e.g., July-September in the US, November-January in Singapore).
• This seasonal cognitive performance decline was observed across nearly all investigated cognitive domains.
• The effect size of this seasonal variation was small, even after adjusting for socioeconomic status or ADHD diagnosis, and significantly smaller than socioeconomic influences on cognition.

Conclusions:

• A generalizable, small-magnitude effect of lower cognitive performance in school-age children coincides with school vacation periods.
• These findings suggest that seasonal variations impact general cognitive skills in children, extending beyond academic performance.
• Recommendations are provided for future data collection and analysis to better understand behavioral patterns across the entire calendar year.