This book presents new theory and empirical studies on the roles of cognitive workload and fatigue on repeated financial decisions. The mathematical models that are developed here utilize two cusp catastrophe functions for discontinuous changes in performance and integrate objective measures of workload, subjective experiences, and individual differences among the decision makers. Additional nonlinear dynamical processes are examined with regard to persistence and antipersistence in decisions, entropy, further explanations of overall performance, and the identification of risk-optimization profiles for long sequences of decisions.