As the day goes on, our self-control wears off – according to one of the theories of cognitive function. But new research challenges this view, proposing that self-control is not dependent on the time of day. To investigate this, researchers observed two groups of students over separate 17-week intervals with 24-hour coverage, as they engaged in voluntary learning and self-testing using an online program. From current models of self-control, results should have shown increasing depletion throughout the day, and that this should translate into less motivation to complete learning sessions. The findings did show a decrease in performance after an hour of concentrating on a single task, but contrary to the current self-control models, the time of day at which the task was started did not affect initial performance. This supports previous findings that suggest that motivation in single-task performance decreases with time, but counters theories of diminishing self-control.


Daniel Randles , Iain Harlow, Michael Inzlicht

Corresponding author:

Daniel Randles, Social Neuroscience Lab, University of Toronto, ON, Email:

Original paper published in PLOS One on September 20, 2017.