A new working paper (abstract; PDF) by Ian Fillmore and Devin G. Pope examines whether “cognitive fatigue” has any impact on exam results. The researchers looked at the number of days students had between AP exams, and found that resting time matters:
In many education and work environments, economic agents must perform several mental tasks in a short period of time. As with physical fatigue, it is likely that cognitive fatigue can occur and affect performance if a series of mental tasks are scheduled close together. In this paper, we identify the impact of time between cognitive tasks on performance in a particular context: the taking of Advanced Placement (AP) exams by high-school students. We exploit the fact that AP exam dates change from year to year, so that students who take two subject exams in one year may have a different number of days between the exams than students who take the same two exams in a different year. We find strong evidence that a shorter amount of time between exams is associated with lower scores, particularly on the second exam. Our estimates suggest that students who take exams with 10 days of separation are 8% more likely to pass both exams than students who take the same two exams with only 1 day of separation.
The race effects are particularly interesting:
Relative to the omitted category (White students), Black and Hispanic students benefit less from a greater number of days between exams. Asian students benefit even more than White students from a greater number of days between exams. The reason behind these heterogeneous effects is unclear and our data do not allow us to distinguish among various explanations. One possible scenario is that certain groups of students simply don’t recover their mental acuity as fast or they get stressed or “burned out” quicker than other groups. Another, perhaps more plausible, mechanism is that the students with larger effect sizes (e.g. females, Asians) study more for AP exams than their counterparts and thus have a higher value of having extra days between exams so as to have more time to “cram” for the second exam.