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On Improvement of Scientific Presentations

¹ Department of Diagnostic Radiology, Allegheny General Hospital, 320 East North Ave., Pittsburgh, PA 15212-4772.

Received September 13, 1999; accepted after revision October 20, 1999.

 
Address correspondence to R. H. Daffner.

Introduction

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The presentation of scientific material either at major meetings, such as the American Roentgen Ray Society and the Radiological Society of North America, or at refresher courses is an important method of conveying new ideas and data to the radiologic community. Unfortunately, the invaluable message is often ruined by a poor choice of either graphics or presentation technique. I have made several observations during my long academic career, which has involved not only presenting scientific papers, but also serving as a moderator for major meetings and organizing refresher courses.

Slide Format

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Most presenters at radiology meetings use the single or dual slide projection format. The latter allows more material to be presented and is especially designed to show either images on one screen with text on another or comparison studies so that the audience can appreciate the differences simultaneously. A few authors have used glitzy multiscreen techniques that often distract the audience. Dual projection has recently been the standard technique, but computerized presentations are being used with greater frequency. The same principles governing slide presentations apply to the computerized techniques.

Before the mid 1980s, most word slides were either typed and then photographed or prepared using professional typesetting and photography. In the mid-to-late 1980s, computer programs were developed that allowed direct composition of slides. Two of the more popular programs are Microsoft PowerPoint (Microsoft, Redmond, WA) and Harvard Graphics (Software Publishing, Santa Clara, CA). Of the two, the PowerPoint program is the more versatile because it allows for easy preparation of either the slide format or the computer disk format. Unfortunately, despite the availability of these programs, I have observed a number of presentations in which the old, typed slides are used. In some instances, it was merely a matter of the speaker using several "oldies but goodies," classic slides, which all veteran presenters have. However, just as it is important to review one's case material, so it is also important to update one's slides, even if nothing has changed.

Updating is very important. In reviewing word slides from presentations that have been used over the years, it often becomes apparent that several different type styles or fonts have been used. In addition, different background colors have sometimes been used. Continuity and the esthetic appearance of a presentation is enhanced by uniformity, and to assure that uniformity, some graphic material may have to be redone.

The presenter's choice of slide type is also important. Three popular types are cardboard, glass, and plastic. Most older slides are in cardboard holders, which are easily bent or frayed along the edges. Damaged slides cause jams in the projector that delay the program and sometimes result in the slides being dropped while the jam is being cleared. Glass slides are more durable; however, they are more fragile, and cracks in glass slides detract from the presentation. More serious is the condensation that occurs between the glass layers. The audience focuses on the changing pattern of the evaporating moisture rather than on the speaker or the image. Glass slides are too thick for some slide trays. Plastic slides are ideal because they eliminate the problems of both cardboard and glass slides. In addition, they are lighter in weight, an added bonus, if the speaker is giving more than one talk at a refresher course. Glass slides cannot be remounted in plastic; however, cardboard slides can and should be remounted when they get old and frayed.

Slide Background and Lettering of Slides

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All of us have our favorite color schemes for our slides. However, many color combinations clash or produce eye strain. A color combination may look acceptable when viewed on a 2 x 2 inch slide, but can be totally unacceptable when projected on a large screen.

As a rule, backgrounds should be dark colors. A medium-blue background with yellow or white lettering is preferable [1]. Green, red, and orange backgrounds are extremely difficult on the eyes. Green, blue, or red lettering is difficult to read regardless of the background. Black letters on any background can produce eye strain.

Slide Content

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Slides should never be crowded. Too much material on a slide necessitates smaller fonts, and individuals sitting at some distance from the screen may not be able to read all of the material. Titles should be divided into two or three lines. Words should be kept to a minimum and should be used only to emphasize the points that the speaker is making [1]. Thompson et al. [1] note that slides with ten or fewer words are much more effective for emphasizing specific points than slides with more than 20 words [1]. How can one determine whether there is too much material on a slide and whether the audience will be able to see it? A simple rule of thumb is to hold the finished slide at arm's length. If you can read all of the material, then the audience seated in the back of the room should also have no trouble reading it.

In addition to limiting the number of words and lines on slides, attention should be given to the amount of new information presented on word slides and on graphs. Attendees often take notes during a presentation; therefore, each word slide should be limited to one or two simple points. Similarly, all charts and graphs should present material in a simple and clear fashion that is easily grasped by the audience without a detailed explanation. Charts showing the scattering of raw data usually require a long time for analysis and are best left for the scientific publication. A line or bar graph is best for showing, in simplified form, the trend the data took.

Images

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I have observed many presentations in which an entire frame of a CT or MR imaging study fills the screen. All this information may orient the observer, but it detracts from the overall presentation by drawing the observer's eye away from the main point. The presenter should cone down on the important portion of the image, whether performed photographically or by computer. For MR images, the type of image (T1- or T2-weighted, short tau inversion recovery, etc.) should be stated by the presenter.

Patient confidentiality is mandatory. It is disconcerting to see patients' names or identification numbers on images presented at meetings. If these cannot be adequately masked off the images, they should be covered with black plastic tape.

In many presentations, serial images are shown to illustrate the changes that have occurred over a period of time, or the natural course of a disease. Many presenters put the dates of the studies on the film to indicate the time sequence. Although this is perfectly acceptable if the case is a classic and is to be used time and time again (as many are), using dates conveys a message to the audience that the presenter is severely limited in his or her case material. For example, if one shows a case dated 1975, the observer might say, "You mean the presenter didn't see any better cases in 25 years?" To overcome this pitfall, I suggest using numbers to indicate the time interval. The index study should be marked with a zero; all subsequent images should be marked with a time interval (days, weeks, months, or years). This way, classic cases can truly become timeless.

Blanks and Fillers

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Dual slide projection has been the standard technique of radiologic scientific presentation for the past 30 years. PowerPoint presentations allow multiple images to be projected at one time, eliminating the need for dual projection. In many instances, the presenter will have data or an image to be projected only on one screen. The question arises, "What do I do with the other screen?" A simple solution is to use a plastic blank slide filler. All too often, the presenter uses a scenic, family, or cartoon slide. Looking at the filler slide instead of at the data being presented is human nature. This method works well when a presenter is unsure of his or her data and deliberately wants to distract the audience; however, such slides are inappropriate in a truly scientific presentation. One well-known speaker uses a blank slide with a single perforation that projects as a white dot on the otherwise black screen. He does this to be assured that there has not been a slide jam. This dot diverts the attention of the audience from digesting the important image to deducing the meaning of the dot.

Pointers on Presentations

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All speakers should be familiar with the differences between a scientific presentation and a refresher course presentation. Presenting a scientific paper at one of the major society meetings is an opportunity to report new research, correct misconceptions, or unveil new technology. This format typically limits presentations to between 8 and 12 min, allowing a scant 2 or 3 min for questions and answers. These presentations challenge both veteran speakers and neophytes to get their points across in the time limit. The idea is to whet the appetite of the attendees, who will mark their program abstracts for future reference in anticipation of the paper being published in the official organ of the society.

The refresher course, on the other hand, is usually conducted at a more leisurely pace. Two basic formats are used: a limited number of topics discussed in-depth or many topics, usually related, discussed as an overview. The first format is used at the major society meetings; the second is typically used in specialty society meetings, such as the International Skeletal Society or the Fleischner Society, and is designed primarily for nonmembers. In refresher courses, speakers may have from 20 to 50 min for their presentations, depending on the format. This allows a more relaxed atmosphere for both the speaker and the audience. There is usually ample time for questions and answers at the end of each presentation.

More and more presentations are being given using digital computerized technology. The advantage of these presentations for the speaker is that he or she is able to both prepare all the material directly, avoiding photography, and have one or more presentation on a single 3.5-inch floppy disk. As previously mentioned, all of the principles governing slide presentations apply to computerized programs. Many of the digital presentations use small fonts that are difficult to see when projected; therefore, the presenter must preview the material and make appropriate changes to avoid this pitfall.

The late Lucy Squire [2] wrote a masterful paper on presenting films at conferences. Although the paper was designed to cover the presentation of radiographs, many of the points that she made apply to slide or PowerPoint presentations. The presenter should follow the old Boy Scout motto, "Be Prepared." The first element of preparation is knowing your topic or subject matter. Equally important is knowing your audience. Are you speaking to an audience of general radiologists, to a group of highly specialized radiologists (such as the International Skeletal Society), to nonradiologists, or to nonphysicians? The same material can be tailored to suit each group. It makes little sense to give an in-depth dissertation on the physics of T1- and T2-weighting to an audience who knows little about the subject and is probably not interested in the details. For this audience, a few general terms and a simple explanation would be better.

Materials should be organized before the presentation and either presented ahead of time to colleagues at home or reviewed in the speaker-ready room at the meeting [1, 2]. Timing and balance are extremely important. In any scientific presentation, the time limit is important because of the number of papers being presented. Many moderators are generous in allowing speakers to run overtime, but it is extremely inconsiderate for a speaker to do so. A balance in the presentation is important. Some speakers assign relatively equal amounts of time for the introduction, methods and materials, results, discussion, and conclusions. Others weight each segment, putting the emphasis on the most important segments. There should be a brief preamble to the presentation, summarizing the material to be presented. This summary should be repeated at the end as a take-away message of two or three important points [2].

The speaker should stand in one place at the podium and not dance about. Excessive movement distracts the audience. Most presentations involve the use of a laser pointer. The presenter should be familiar with the use of the pointer and should turn the pointer on and off only when absolutely necessary. Too many speakers leave the pointer on, make large circles on the projected material, or wave the pointer around. A small bead of light draws the observers' eyes like a moth is drawn to a flame. Once again, the audience is distracted by this extraneous motion instead of watching the material being presented [2].

Some speakers read their presentations for fear that they will leave out important information. However, audiences generally find this reading to be somewhat disconcerting. Speakers should practice the presentation until they can recite it in their sleep. Foreign speakers who have difficulty with English are a notable exception and are to be admired for their perseverance in presenting information in a foreign language.

The late Dr. Benjamin Felson was renowned for his humor and his anecdotes. Many speakers try to add a touch of humor to their presentations. Although the intent is to lighten the atmosphere, this attempt may backfire. At refresher courses, the speakers should remember that the attendees are paying for information and not for stand-up comedy. In addition, it is the rare joke that is not made at the expense of one group or another; such joking is not acceptable in today's politically correct atmosphere. Instead of adding such material, a presenter can lighten the atmosphere with an appropriate remark about the case being shown. For example, in many of my presentations on trauma, simply giving the clinical history has provided levity.

Finally, it is extremely important for a speaker to know the physical environment in which he or she will be speaking. I always make a point to check out every presentation auditorium, walk to the podium, look at the screen, and determine whether I will be able to see the screen from the speaker's podium. In many instances, seeing the screen may be difficult because of the extreme angle at which the podium is placed in relation to the screen. If this angle is a problem, it should be called to the attention of those in charge of the physical arrangements before the meeting or presentation. In addition to checking the point of view from the podium, it is also important not only to familiarize oneself with the pointer and the slide or computer image advancers, but also to check in with the projectionist and learn his or her name. If there is a technical problem, it is beneficial to address the projectionist by name. After the presentation, be sure to thank your projectionist.

Summary

Top Introduction Slide Format Slide Background and Lettering... Slide Content Images Blanks and Fillers Pointers on Presentations Summary References

 
Scientific presentations require a great deal of preparation. Background lettering colors on the slide, the number of words on a slide, and the elimination of distracting factors are all important in determining the success of one's presentation. This brief paper has attempted to address some of these issues.

References

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1. Thompson WM, Mitchell RL, Halvorsen RA Jr, Foster WL Jr, Roberts L. Scientific presentations: what to do and what not to do. Invest Radiol 1987;22:244 -245[Medline]
2. Squire LF. On the art of presenting films at conferences. Radiol Clin North Am 1971;9:149 -158[Medline]

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				R. H. Daffner On Improvement of Scientific Presentations: Using PowerPoint Am. J. Roentgenol., July 1, 2003; 181(1): 47 - 49. [Full Text] [PDF]

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