Assertion-evidence Presentation Approach Leads to Better Comprehension and Retention of Complex Technical Concepts

Open Access
Wolfe, Keri L
Area of Honors:
Communication Arts and Sciences
Bachelor of Science
Document Type:
Thesis Supervisors:
  • Michael P Alley, Thesis Supervisor
  • Lori Ann Bedell, Honors Advisor
  • Darrell Velegol, Honors Advisor
  • technical communication
  • engineering communication
  • assertion-evidence
  • PowerPoint
  • slide design
  • visual aids
This paper describes two experiments that compare students’ learning from a presentation that relies on the commonly practiced topic-subtopic slide structure versus students’ learning from a presentation that follows an assertion-evidence slide structure. In the topic-subtopic approach, the headline and body of the slide are heavily influenced by PowerPoint’s default outline structure. This structure consists of a topic-phrase headline supported either by a bulleted list of subtopics or by a bulleted list and a graphic. In the assertion-evidence structure, the heading is a succinct sentence assertion and the body of the slide supports that heading with visual evidence: photographs, drawings, diagrams, or graphs. In each of the two experiments presented in this paper, two audiences heard the same recorded presentation, but one audience viewed topic-subtopic slides and another viewed assertion-evidence slides. The slide design differed between the two sets of slides in terms of different headlines, different amounts of text in the body, and different visual designs. The presentations presented background information about cancer and then explained the process of how magnetic resonance imaging can detect cancerous tumors. Students were tested immediately after the presentation and then again several days later. In the first experiment, the increased understanding of the complex concept by the audience viewing the assertion-evidence slides was statistically significant (p<.001). This finding was reflected in the essay test results, as well as the short- and long-term retention tests. The overall averages were higher for the assertion-evidence group, but this difference was most emphasized in questions pertaining to primary details of the process presented. The assertion-evidence group also had fewer misconceptions about the process, which supports the hypothesis that the assertion-evidence approach focuses the audience on main points of the presentation, rather than seductive details. In the second experiment, the topic-subtopic slides contained more animations and better quality visual evidence quality than the topic-subtopic slides used in the first experiment. Both of these features more closely matched typical characteristics of the assertion-evidence approach. On the questions that tested for comprehension and retention of more complex concepts, students learning from the assertion-evidence slides scored higher than did students learning from topic-subtopic slides. However, unlike the first experiment, that difference was not statistically significant. While the size of that evidence was typically smaller, the auditorium in which the experiment occurred had a larger projected image than occurs in most rooms. Therefore, the design of visual evidence appears to have played a larger role in the comprehension of complex concepts than previously assumed. Because the visual evidence for the topic-subtopic slides were created using an assertion-evidence approach to slide design, the question arises as to whether the positive effect of explanatory graphics was able to offset negative effects on learning associated with other features of the topic-subtopic structure. Also tested was the short-term and long-term recall of statistics and other factual information from the presentation. For more important facts that were included on both sets of slides (either as text or as visual evidence), the assertion-evidence participants had a recall that was as good as, or in several cases distinctly better, than participants viewing the topic-subtopic slides. That increase in recall can be attributed to those details being emphasized in the headline or in graphics on the assertion-evidence slides, as opposed to bulleted lists on the topic-subtopic slides. Not surprisingly, the topic-subtopic participants fared better with minor details—details that the assertion-evidence approach did not consider important enough to place on the slides. This potential interaction between slide structure and information recall raises the question of whether the better recall of that less important information by the topic-subtopic group occurred at the expense of not remembering the primary details as well.