AC 2012-4193: HIGH-QUALITY VISUAL EVIDENCE ON PRESENTA- TION SLIDES - PDF document

AC 2012-4193: HIGH-QUALITY VISUAL EVIDENCE ON PRESENTA- TION SLIDES MAY OFFSET THE NEGATIVE EFFECTS OF REDUN- DANT TEXT AND PHRASE HEADINGS Ms. Keri Lynn Wolfe, Pennsylvania State University Keri Wolfe is a senior Chemical Engineering student at the Pennsylvania State University. She is a Leon- hard Scholar and a German minor. She has been inducted to XE Chemical Engineering Honors Society and A German Honors Society. She is most active in Engineering Ambassadors and the Society of Women Engineers. Keri is conducting engineering education research to fulfill her Schreyer Honors College Un- dergraduate Thesis requirement. Mr. Michael Alley, Pennsylvania State University, University Park Michael Alley is an Associate Professor of engineering communication at Pennsylvania State University and a part of the Leonhard Center for the Enhancement of Engineering Education. He is the author of The Craft of Scientific Presentations (Springer-Verlag) and has taught professional workshops on technical presentations on five different continents. Dr. Joanna K. Garner, Old Dominion University Page 25.694.1 � American Society for Engineering Education, 2012 c

High Quality Visual Evidence on Presentation Slides May Offset the Negative Effects of Redundant Text and Phrase Headings Abstract This paper compares students’ learning from a presentation that relies on th e topic- subtopic slide structure versus students’ learning from a presentation that follows an assertion - evidence slide structure. In our experiment, two audiences heard the same recorded presentation, but one audience (48 participants) viewed topic-subtopic slides and another (52 participants) viewed assertion-evidence slides. The presentation, which took about 10 minutes to view, 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. One conclusion drawn from this experiment is that although not statistically significant, a positive trend occurred for the assertion-evidence slides leading to better comprehension of complex concepts. However, in comparison with results from participants viewing topic-subtopic slides in an earlier experiment, the participants viewing the topic-subtopic slides in the experiment of this paper fared much better. Two possibilities explain this result. One possible reason that the comprehension and retention of complex concepts in the topic-subtopic approach of this experiment fared better is that these slides included much more animation of text and images than in the previous experiment. Another possible reason for the increased scores by the topic-subtopic participants has to do with the visual evidence used for the topic-subtopic slides. For all eight slides presenting the complex concept of how magnetic resonance imaging works, the visual evidence had the same design as in the assertion-evidence slides. While the size of that evidence was typically smaller, the auditorium in which the experiment occurred had a relatively larger projected image than exists in most rooms. If the visual evidence of the topic-subtopic slides significantly affected the results, then the design of visual evidence appears to play a larger role in the comprehension of complex concepts than previously assumed. Introduction In engineering conferences, meetings, and classrooms, presentation slides are often used to communicate key concepts and factual details. A recent sampling of several thousand slides from engineering and science revealed that almost two-thirds had a topic-phrase headline supported by a bulleted list of subtopics. 1 Because slides are used so often by engineering educators to communicate research, to teach students, and to have students demonstrate what they have learned, the question arises how effective this topic-subtopic structure is, compared with other slide structures, for helping audiences understand and remember the information In a recent study, we found that presentation slides following an assertion-evidence structure led to statistically significant increases in comprehension of complex concepts in Page 25.694.2 comparison with slides following a topic-subtopic structure (p < .001). 2 In the assertion- 1

evidence structure, the headline is a succinct sentence assertion and the body of the slide supports that headline with visual evidence: photographs, drawings, diagrams, or graphs. 3 This paper tries to address why the assertion-evidence approach leads to this higher comprehension of complex concepts. Substantial differences between the assertion-evidence slide structure and the topic- subtopic structure occur in both the text and the visual evidence. First, the assertion-evidence structure has much less text — typically having about half the number of words projected per minute. 4 Second, the text is presented in starkly different ways. In the assertion-evidence structure, most of the text occurs in the sentence headline, which serves to provide a succinct summary of the slide. Put another way, the sentence headline of an assertion-evidence slide can be thought of as a safety net for the audience. This safety net allows the audience to catch up if the audience loses track of what the speaker is saying. In contrast, the main takeaway of a topic-subtopic slide is often divided among multiple elements: the topic-phrase headline and text blocks in the bulleted list. In this study, we tried to isolate the effect of the text in the following way. For both sets of slides, we incorporated the same visual evidence. Moreover, we selected a room in which the screen was large so that the diminished size of graphics in the common practice would not pose a problem for those sitting in the back rows. Methods To test the effects of text in the assertion-evidence structure versus the effects of text the commonly practiced topic-subtopic structure, we created two sets of presentation slides that followed a single recorded script. Each set had 14 slides. However, one set was made following the assertion-evidence approach, displaying a full-sentence assertion that was supported by visual evidence. The other set of slides followed the topic-subtopic structure consisting of a phrase headline supported either by bulleted subtopics or by bulleted topics and a graphic (photograph, drawing, diagram, or graph). In this study, on all slides conveying a complex topic, we incorporated visual evidence. Presented in Figure 1 are three slides from the assertion-evidence set, and presented in Figure 2 are three slides from the topic-subtopic set. The script developed for this experiment was meant both to interest the audience and to introduce a new and challenging technical concept: the process of Magnetic Resonance Imaging (MRI). Magnetic resonance imaging is a good topic for this experiment, because the process is typically not taught to undergraduates, who composed our test audience. The full script can be found in Appendix A. Both the script and the first set of slides wascreated followed the format of the assertion-evidence style, which is outlined in the literature. 5 In accordance with these guidelines, text was limited to a two-line full-sentence assertion at the top of the slide and call- out for the visual evi dence in the slide’s body. No text block was no more than two lines of text. In addition, the visual evidence on the slides was created specifically for the headlines of the assertion-evidence slide model. Every slide in the assertion-evidence presentation had at least one photograph, drawing, diagram, or graph. In addition, layering animation techniques were used to show the progression of process steps. Page 25.694.3 2

When the RF wave ceases, the magnetic field forces atoms to realign and release energy Applied RF waves add energy to hydrogen atoms, causing some to fall out of alignment with the magnetic field Applying a magnetic field causes the spins of atoms in the body to be aligned parallel to the field Figure 1: Sample slides from assertion-evidence presentation about the process of magnetic resonance imaging. 6 Note that each of these slides had an additional layer of visual evidence that animated in during the discussion of the slide. Shown here are the final layers. Page 25.694.4 3

When Gradient Magnets Turn Off  Field from superconducting magnet realigns atoms with RF energy  These atoms move to lower energy state and release RF wave  Transceiver can detect these waves  The frequency of RF wave depends on molecule containing the H atom ENGR HEALTH When RF Waves Are Applied  Transceiver sends pulse of RF waves that targets hydrogen  Hydrogen atoms: plentiful in body  Body is more than 55% water  Some H atoms absorb enough energy to overcome magnetic field  These atoms in higher energy state ENGR HEALTH How the MRI Process Begins  Atoms have spins, which normally point in random directions  MRI patient is placed in strong magnetic field so that spins align with field  Gradient magnets send counter- acting field to small cube (voxel)  Field significantly lower in this voxel ENGR HEALTH Figure 2: Sample slides from the topic-subtopic presentation about the process of magnetic resonance imaging. Note that each of these slides had animation of bulleted points and images during the discussion of the slide. Shown here are the final layers. Page 25.694.5 4