Incentive, practice, instruction, and feedback were manipulated in a series of four 2 x 2 factorial studies, with Air Force Reserve Officer Training Corps cadets and graduate students in education, to determine the individual and combined effects of these variables on learner performance (both speed and accuracy) of an aircraft comprehension task. For each of the experiments, the report provides details on: methods, subjects, materials, procedures, criterion measures, design and data analyses, results, and discussion of results. Although cadets who either practiced the task or were offered an incentive performed significantly faster on the post-test than learners who did not receive these treatments, the experiments generally indicated that instruction, when it is well-designed, appears to be a variable of such impact that it leaves little room for improvement in learner performance that might be attributable to such refinement as practice, incentive, and feedback. Sample instructional, practice, and post-test materials and tables of results are included. (Author/PR)