In the area of aptitude-treatment interaction (ATI) research, an outcome variable which has received relatively little attention is differential student learning times, or students' relative learning efficiency on one treatment as opposed to another. Although it has been argued that learning times are not appropriate variables for evaluating treatment effectiveness, the case may be made that (a) learning times are appropriate ATI outcome variables to examine in the increasing number of self-paced, criterion-referenced, and computer-based instructional environments; and (b) the study of differential learning time outcomes from treatments implemented in these self-paced environments can help advance our understanding of treatment component/learning strategy matches that contribute to increased learning efficiency. To determine the validity of this claim, generalizations from a number of ATI studies conducted in the context of the Air Force Advanced Instructional System are discussed. (Author/GSK)