Visuals are an important part of oral presentations: they can be used to highlight important information, explain technical concepts and details that are difficult to explain through words alone, and can help connect the listener to the content.
In planning presentation visuals, you have the same options as with writing, but will have to adjust your visuals for presentation on a screen, further away from your audience (than a piece of paper arms length away).
The following issues are particularly important in a presentation setting:
Introduce the graphic and explain its role in the presentation in words. Make sure that the graphic has a specific purpose in your presentation, and use your speech to identify its purpose and to highlight the key parts of the visual that serve that purpose. For example, when presenting a table of results, highlight (visually, through gestures, and in words) the cells that hold the most significant data.
Make sure that the precision of the illustration matches the precision of the speech: this is of particular concern when using graphics originally design for a written text, which is likely to provide a more detailed accompanying description, in oral presentations. Adjust the visual so that it suits the presentation content.
Ensure than graphics are properly titled (i.e. Figure 1.1: Cut Away Drawing of Solid Fuel Rocket Boosters) and labeled. In an oral presentation setting, it is likely that some listeners may miss your introduction to the graphic. Readers who miss this introduction can simply flip back; listeners do not have this luxury. The title and the labels hold the key to interpreting the graphic element and its role in the presentation.
In addition to these shared issues, using graphics in an oral communication setting presents some other challenges:
1. Orientation of Visuals: When using transparencies, always use landscape orientation rather than portrait. This is not a constraint introduced by PowerPoint (which limits users to landscape format), but by the fact that a landscape oriented slide fits better on a projector than portrait oriented ones. Landscape oriented slides allow you to use more of the space available on the slide, without having to adjust the slide during the presentation.
2. Text / Image Size / Resolution: The titles and labels need to be readable from a distance. This means that text should be a minimum of 18 point in size (24 point is typical).
While Times New Roman is typically the standard font for written documents, less print oriented fonts with harder edges and fewer curves are more suitable for presentation slides. Commonly used fonts for oral presentations include: Arial, Helvetica and Tahoma.
Furthermore, a standard approach to using images from written documents is simply to resize the image so that it fits the slide. This sometimes works, but resizing a small, low-resolution image to a larger size can result in fuzzy images that are difficult to interpret.
3. Text Based Slides: In an oral presentation, text based slides are common. They function to highlight the key points and reinforce the structure of the presentation. However, text based slides also encourage listeners to read, rather than listen. This is especially true if the presenter reads the text of the slide: avoid this. To use text based slides effectively, minimize the amount of the text on the slide by using note form instead of complete sentences, and leaving the details for your speech, rather than on the slide. The slide presented below is an example of a poorly designed slide, using too much text:
- The Orbiter is one key component of the space shuttle, and holds the astronauts along with all the equipment
- The solid rocket boosters are another, and provide the initial thrust required to get the shuttle out of the atmosphere. It is jettisoned and recovered.
- The liquid rocket booster is the final component, and provides the thrust required to get the rocket into orbit. It is jettionsed after leaving the atmosphere, and burns up on reentry.
Reduce text by adding a title (Components) and using note form:
- Holds astronauts and equipment
- Sold Rocket Boosters:
- Provides initial thrust to exit atmosphere
- Jettisoned and recovered
- Liquid Rocket Booster:
- Provides thrust to achieve orbit
- Jettisoned and burns up on reentry
4. The Dangers of Presentation Technologies: The devices and programs we use to produce and display our visuals in oral presentations present their own sets of dangers:
Overhead Slide Projectors / Transparencies: When using slides, make sure that you’ve oriented yourself with the projector, ordered and prepared your slides well – presenters can waste a significant amount of time and lose points by putting slides on backwards or upside down, flipping through their transparencies to find the right ones, and not placing the transparency on the right spot or correctly aligning their slide
Blackboards / Whiteboards / Flip Charts: The danger in using these is that you’ll have to draw the diagram on the fly – this can be a good thing, if the drawing is not too technical and you can maintain your speech and contact with the audience throughout the talk. However, most presenters will wind up with their back to the audience, focused on drawing, rather than maintaining their rapport with the audience.
PowerPoint (or other presentation program): is both a godsend and a curse. It can help support presentations, but has also been blamed for hiding shoddy engineering or misrepresenting information . When using PowerPoint:
Make every effort to ensure that the technology works, but prepare for the worst: many presenters have been humbled by an non-functioning, missing or incompatible projector, cables or laptop.
Avoid using Clip Art and animations, unless they have a specific purpose other than decoration. Animations can slow down the pace of the talk or distract from the content. The ‘Appear’ animation is useful when well integrated with the talk; use it to bring up points on screen when you discuss them. Clip art usually has little purpose and only distract.
Similarly, choose a presentation template wisely. Avoid garish and low contrast color schemes that can make text difficult to read.
When using PowerPoint, you have two dangerous distractions: the laptop screen and the actual screen. Presenters often use the Slide Notes and Presenter View functions instead of hard copy (on a sheet of paper or cue cards) notes. However, be aware that presenters are much more conscious of eye contact when using hard copy notes: you’re less likely to read off your notes than you are to read off the computer screen.
5. Slide timing / number: The amount of time that a slide is left on the projector is an important consideration in planning. As a general rule, slides left on screen for less than 20-30 seconds don’t allow enough time for the audience to digest the material properly. Slides should also not be left on the projector after you’ve finished discussing the material on the slide – take off the slide after you’re done with it.
A related issue is the number of slides suitable for a presentation of X minutes. A general guideline is a maximum of 2 x # of minutes in a presentation; any more and you’ll be flipping through slides too quickly. Note that the figure is a maximum, not a recommended number.
6. Using Slides to Make Structure Explicit: Slides can help to make the structure of the talk explicit at the beginning and throughout the presentation. An overview slide is often useful while you outline the path of your presentation; slide titles corresponding to the different components (sometimes numbered) of the talk remind the audience of where they are in the talk.
 Tufte, E. Visual Explanations: Images and Quantities, Evidence and Narrative. Chesire, Conn. : Graphics Press, 1997.