During times of crisis, do cognitive processes shape leaders’ procurement decisions in predictable ways? Drawing on psychological literature, we propose four factors that may have a substantial influence on how much money leaders engaged in ongoing disputes allocate to their military: (1) striving for superiority versus striving for parity in military resources; (2) uncertainty regarding the characteristics of weapons systems; (3) ambiguity regarding the overall capacities of weapons systems; and (4) the tone of messages that adversaries send to one another. The effects of these factors are investigated using a laboratory simulation that combines both experimental and quasi-experimental elements. The results indicate that striving for superiority has a significant effect on defense spending, as does the tone of an opponent’s message. By way of contrast, neither uncertainty nor ambiguity exerts a statistically discernable impact on the level of defense spending.