This paper describes an empirical study conducted to validate a computational model of dynamic task prioritization based on a framework proposed by Zhang and Feyen (2005). Three key factors in task prioritization were manipulated: processing time, available time, and task valence. Because earlier studies did not investigate how people prioritize tasks when valence and temporal characteristics conflict, this study examined how these conflicts are resolved. 20 subjects completed 54 time-limited task scenarios. Each scenario consisted of two or four concurrent tasks, each assigned a point value for completion. Subjects were instructed to maximize points scored. Results indicated that, although valence was predominant in determining task selection, it failed to explain all instances. Instead, a hierarchy of task prioritization was revealed in which subjects first checked what tasks were doable (e.g., self-efficacy), then applied rules first regarding valence, then temporal characteristics, and then others (e.g., task location).