Modeling motivation using goal competition in mental fatigue studies

Motivation can counteract the effects of mental fatigue. However, the underlying mechanism by which motivation affects performance in mentally fatiguing tasks is obscure. In this paper, we propose goal competition as a paradigm to understand the role of motivation and built three models of mental fatigue studies to demonstrate the mechanism in a cognitive architecture named PRIMs. Each of these studies explored the impact of reward and mental fatigue on performance. Overall, performance decreased in nonreward conditions but remained stable in reward conditions. The comparisons between our models and empirical data showed that our models were able to capture human performance. We managed to model changes in performance levels by adjusting the value of the main task goals, which controls the competition with distractions. In all the tasks modeled, the best model fits were obtained by a linear decrease in goal activation, suggesting this is a general pattern. We discuss possible mechanisms for activation decrease, and the potential of goal competition to model motivation.