Rhythms of Cognitive Performance

Our cognitive abilities wax and wane over the course of the day. In particular, alertness — a central component underlying a wide range of cognitive functions from learning to problem-solving to memory consolidation — fluctuates reflecting a circadian rhythm. It is also influenced by a number of other factors, including sleep and one’s internal body clock type (for example, whether one is an “early bird” or a “night owl”).

Given the key role alertness plays in cognitive performance, improving individuals’ everyday alertness could have far-reaching positive impacts. However, this requires a better understanding of the fluctuating nature of our alertness and the impacts of behavioral, environmental, social, and biological factors in a real-world setup.

Towards this goal, we developed a smartphone app for in-situ assessment of alertness. We also collect diverse streams of self-reported including body clock type, sleep information, and stimulant use. We found that alertness can oscillate approximately 30% depending on time and body clock type and that Daylight Savings Time, hours slept, and stimulant intake can influence alertness as well.

Based on these findings, we develop novel methods for unobtrusively and continuously assessing alertness. In estimating response time, our model achieves a root-mean-square error (RMSE) of 80.64 milliseconds, which is significantly lower than the 500ms threshold used as a standard indicator of impaired cognitive ability. Our developed methods for unobtrusive and continuous assessment of alertness paves the way for a new class of technology that can significantly improve learning, occupational safety and work performance.


Supplementary Materials