Among its other benefits, schooling may expand students’ underlying capacity for cognition, including the ability to engage in effortful thinking, which constitutes a more expansive view of how education shapes general human capital. This research examines this phenomenon by focusing on how schooling engages students in effortful thinking for continuous stretches of time. In other words, do in-class exercises like reading and other forms of sustained concentration expand cognitive endurance, or the ability to sustain performance over time during a cognitively effortful task? Existing literature suggests that the answer is “yes,” but evidence remains limited. 

To address this question, the authors designed a field experiment in a setting where time in focused cognitive activity is limited: low-income primary schools in India. Their sample comprised 1,636 students across six schools in grades 1-5, who were randomized to either receive continuous stretches of cognitive practice, or to a control class period with no such practice. The authors also employed sub-treatments (Math and Games) to further explore effects of continuous cognitive practice (please see the full working paper for more details on their research design), to find the following:

• The act of effortful thinking alone has broad benefits—proxied by improved school performance across unrelated domains. On average, receiving cognitive practice mitigates performance decline in the second half of the test by 21.9%, with similar average effects across the Math arm (21.9%) and Games arm (22%).
• Effortful thinking changes a particular capacity: cognitive endurance. Control students, for example, exhibit significant cognitive fatigue: the probability of getting a given question correct declines by 12% from the beginning to the end of the tests on average. 

The authors stress that their findings do not preclude the possibility that their treatments may have benefits through channels other than cognitive endurance that are not studied in this work. Even so, they view their two main sets of findings as offering complementary evidence on the potential link between schooling and generalized mental capacity. And those benefits likely extend beyond school. For example, the authors also document substantial performance declines among full-time data entry workers and among voters at the ballot box, with more severe declines among more disadvantaged populations. While only suggestive, the patterns provide impetus for additional work on cognitive endurance.