Cognitive fatigue influences students' performance on standardized tests
Significance We identify one potential source of bias that influences children's performance on standardized tests and that is predictable based on psychological theory: the time at which students take the test. Using test data for all children attending Danish public schools between school years 2009/10 and 2012/13, we find that, for every hour later in the day, test scores decrease by 0.9% of an SD. In addition, a 20 to 30 minute break improves average test scores. Time of day affects students' test performance because, over the course of a regular day, students' mental resources get taxed. Thus, as the day wears on, students become increasingly fatigued and consequently more likely to underperform on a standardized test. Using test data for all children attending Danish public schools between school years 2009/10 and 2012/13, we examine how the time of the test affects performance. Test time is determined by the weekly class schedule and computer availability at the school. We find that, for every hour later in the day, test performance decreases by 0.9% of an SD (95% CI, 0.7 1.0% However, a 20 to 30 minute break improves average test performance by 1.7% of an SD (95% CI, 1.2 2.2% These findings have two important policy implications: First, cognitive fatigue should be taken into consideration when deciding on the length of the school day and the frequency and duration of breaks throughout the day. Second, school accountability systems should control for the influence of external factors on test scores.
Proceedings of the National Academy of Sciences