Mental fatigue: New model could improve measurement of its impact

Despite more than a century of studies, the origin and effects of mental fatigue are still under debate in the research community. Mental fatigue is associated with reduced effort on demanding tasks, causing performance and efficiency to decline.

Researchers in the Wm Michael Barnes ’64 Department of Industrial & Systems Engineering at Texas A&M University, in collaboration with the Department of Psychological & Brain Sciences and the Department of Engineering Technology & Industrial Distribution, are working to develop a mathematical way to investigate the impact of mental fatigue on effort exertion and decision-making.

Industrial and systems professor Alfredo Garcia directs this research and works with doctoral student Zhide Wang.

Wang said one obstacle in researching mental fatigue is its subjectivity — its effects and symptoms can vary widely across different people. He said a better understanding of mental fatigue’s influence could have both academic and economic impacts as a building block of psychological research.

“Insights about mental fatigue may help explain why people sometimes get bored or distracted in a short time, but in other cases, people can maintain a state of high efficiency without feeling tired,” Wang said. “On the economic side, understanding the mechanism of mental fatigue may help improve the overall efficiency of a system.”

Wang’s model is unique from existing ones because it adopts a framework that relates mental fatigue to the value of decision-making — the perceived value of deciding to complete a task. The researchers hypothesized that mental fatigue discounts the value of a task, making that task not as attractive, which explains why people tend to quit when tired. 

“We proposed a method to determine the value of the task from the subjects’ behaviors and decisions,” Wang said. “Our model embraced the nature of mental fatigue, treating objective measurements as an indicator of subjective fatigue rather than treating the measurement as mental fatigue itself.”