Instructors' use of humor is generally a positive influence on student outcomes. However, examinations of humor have found that specific types of messages may not impact, or may even reverse, its positive effect. Instructional humor processing theory (IHPT) has been used to explain how humor impacts student learning. The current study sought to examine the tenets of this theory by testing whether the relationships articulated by its authors function the way the theory predicts they should. Three hundred participants responded to measures assessing their perceptions of affective learning, attention, self-determination, cognitive engagement, perceived cognitive learning, and instructors' humor. Results indicated that IHPT did not adequately explain the relationship between instructor humor and perceived cognitive learning. However, self-determination theory was a suitable alternative explanation.