The purpose of this study was to examine the effects of visual representations and time-compressed instruction on learning and learners' perceptions of cognitive load. Time-compressed instruction refers to instruction that has been increased in speed without sacrificing quality. It was anticipated that learners would be able to gain a conceptual understanding of technical material at normal and moderately compressed (25%) speeds while instruction presented at 50% compression would depresses it. Visual representations (images/diagrams) have been shown to support learning from a multimedia environment when presented with verbal representations. Thus, it was anticipated that visuals would support learning in a time-compressed environment. This study employed 216 undergraduate students from a medium sized university in a 2x3 factorial design. The independent variables were visuals (visual, no-visual) and compression rates (0%, 25%, 50%). Participants listened to audio instruction of the heart and those in the visuals condition also viewed 19 diagrams that corresponded to the verbal instruction. The dependent variables consisted of four achievement tests: drawing, identification, terminology, and comprehension. Total test, Review Behaviors (back and replay buttons), time-on-task, and perceptions of cognitive load served as additional dependent variables. Prior knowledge of biology was also measured and considered for use as a covariate. Overall, scores on the knowledge-based posttest measures indicate that learning is not significantly affected at the 25% rate, but it is depressed at the 50% compression rate. Participants who listened to compressed instruction at the 50% rate obtained lower scores on the total, drawing, and identification tests than did those in who listened to either uncompressed instruction or instruction at the 25% compression rate. There was also an affect of visuals on learning. Participants who viewed visuals obtained higher scores than those who did not view visuals for the total, drawing, identification, and terminology tests. Additionally, there was visual by compression interaction for the comprehension test, which indicated that at 25% compression, high-level knowledge is depressed unless visuals are presented. The cognitive load measure indicated that normal and moderately compressed (25%) instruction use a similar amount of cognitive load, however this is increased at 50%. Participants who viewed visuals indicated they used less cognitive load than did those participants who were not presented visuals. Although participants could review the material, the uncompressed version took the greatest amount of time. The 25% compression group took longer than the 50% compression group. In sum, the results of this study indicate that listening to normal or moderately compressed (25%) instruction in a multimedia environment supports learning. At these speeds, cognitive load is not increased thus allowing learners to gain a conceptual understanding of the material. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]