简明扼要的幻灯片技巧

PowerPoint tips that are clear and to the point

I spent the weekend on the Island of Guam (three hours south-east of Osaka) finishing up a good quick read on presenting better with slideware in a new book called Clear and to the point: 8 psychological principles for compelling powerpoint presentations by Stephen Kosslyn. I would like to add this book to the short list of books on the topic worthy of your money. There may be nothing necessarily new for the most experienced of you in this book, but because the advice comes to you from a renowned cognitive neuroscientist from Harvard, who aligns his list of presentation and PowerPoint "do's & don'ts" with sound psychological principles, this book will be of help to you as you try to change your own "PowerPoint culture" around you. It's one thing when a designer says the current methods are flawed, but it is quite another when a cognitive neuroscientist says so. The book is by no means the final word on presenting with slides, but it does offer plenty of graphic examples of what works and what doesn't, and it will give you some "hard evidence" to use while you try to persuade your own entrenched curmudgeons trying to defend the status quo.

Kosslyn says that presentation success can be virtually defined by meeting these three goals:

(1) Connect with your audience
(2) Direct and hold their attention
(3) Promote understanding & memory

In other words, you must (1) make a connection with your audience and their goals and their interests, (2) you must get and keep their attention and interest and let them know what is important and what is not, and (3) you must make it easy for them to follow, digest, and remember your material. The eight principles are grouped around these three goals in an organized fashion. You'll have to get the book to get all the details, applications, and visual examples, but basically the principles are grouped like this:

Goal 1: Connect with your audience. This goal is supported by the principle of Relevance and the principle of Appropriate Knowledge. Do not include too much nor too little information, and select information and use language appropriate for your particular audience.

Goal 2: Direct and hold attention. This goal is supported by the principles of Salience, Discriminability, and Perceptual Organization. Attention is drawn to areas that are perceptibly different, so leverage design principles such as contrast and make differences big and obvious. Or as graphic designer Robin Williams would say, " Don't be a wimp!" Also remember that people will naturally tend to group similar elements into a single unit.

Goal 3: Promote understanding and memory. This goal is supported by the principle of Compatibility, the principle of Informative Changes, and the principle of Capacity Limitations. Messages are easier to remember when they are compatible with meaning. For example, the word Red presented in green text violates this principle as would a graph about the homeless cat population in Osaka decorated with a background image of people playing with their healthy dogs. Remember too that people expect any change in your presentations — such as a sudden interjection of a joke or a story, or a visual change in slide color or an animation, etc. — to have meaning, and when they don't have a meaning this becomes noise and hurts effectiveness. And of course, audiences can only retain a limited amount of information in a presentation (see cognitive load theory), so choose carefully and do not try to stuff people's brains with more and more information. It won't work.

Backgrounds, salience, and compatibility
Let's use two of the principles, salience and compatibility, to examine the single issue of slide backgrounds. The most important element of your design should also be the most salient, says Kosslyn. This could be done in many ways such as with larger or bold type, color choices, positioning, and myriad other ways that help guide the viewer's eyes. Generally, slide backgrounds should have low salience, says Kosslyn. That is, backgrounds should be simple without lots of perceptible differences among the background image itself since this would interfere with the foreground elements. And if you use a photo for your background image, Kosslyn reminds us to use a background image that underlines our message instead of undermining it. A good background, says, Kosslyn, can "...allow you to underline your message effectively, or it can create confusion, the background image should not conflict with the message of the display." Let's looks at some examples below.

   
Above: These are posters I found in two store fronts at a shopping mall in Guam Sunday. The one on the left uses three colors (white, red, black), the one on the right has over twice as many colors at seven (yellow, green, blue, red, black, violet, and white). In both cases the key element is the number set in large type: 40% and 50% are what attracts the eye of the shoppers looking for a deal ("off" and "%" are made smaller because they are a step down in importance and are assumed or implied given the context). The limitations of the discount (that they are for selected items only and that you have to buy one first at full price to get the discount on the shoes, etc.) are made subordinate and may in fact be missed until the clerk informs the customer who is now all ready in the store. The power of the "40% Off" on the colorful poster for a game software shop is reduced due to weaker overall design priority of the poster, which even includes superfluous clip art, and in the end simply blends into the sea of noise.(The poster reminds me of some PowerPoint slides that have a large title competing with the more important elements in the slide). The poster for the shoe store is a good example of salience ("Attention is drawn to large perceptible difference") as it is clear which element is the most important.

Let's look below at a few different ways to treat a chart on cell phone internet connectivity rates from 2004. The theme in this case is how far ahead Japan and South Korea are compared to the rest of the world in this area. It is not necessary for every bar to be a different color. South Korea is highlighted because that is the focus of discussion.

 
Above Left: Background image from this PowerPoint template has too much salience itself and competes with the chart in the foreground. Right: Here the contrast is better between the background and the foreground, but the sand and beach ball are not compatible with the message. The background image (also a PowerPoint template) may be appropriate if the chart was comparing sunburn cases or days spent at resort holidays, etc. Still, you could find a better image elsewhere rather than using a tired template.

 
Above Left: Besides the color being inappropriate for this chart, the template has a fixed place for the slide title that is nearly a third down the page which interferes with the legibility of the text. We could reduce the size of the chart and place our title in it's designated place, but that would mean the top third of the slide is taken up by ornamentation. Right: The photo is appropriate perhaps for a presentation on organic farming but is not compatible with mobile phones. There are also some contrast and legibility issues as some of the text is difficult to see.

 
Above: A background photo of a cell phone user in Japan or South Korea may work. This photo does not make for great contrast, however. Contrast can be helped by placing a dark transparent box behind the chart, and still further by adding a Gaussian blur to the background image.

   
Above: I prefer to keep slides quite simple when displaying charts, graphs, or tables. Either of these may work. A white background can make for good contrast with dark text and other elements (nothing has more contrast than black and white) and works well when your room is relatively bright. In a dark room, however, a white background may be overpowering.

Clear and to the point gives a great amount of specific advice that's rooted in well-known psychological principles. I have no issues at all with the principles outlined by the author, but any time you give specific do's & don'ts in a book like this you are bound to have people disagree with some of your example treatments. I have some minor issues with only a few of the slide examples in the book, but all-in-all I would say that this is one of the most useful books on PowerPoint to ever be printed. Why this is not getting more press and more sales is a huge mystery — it's as if Oxford Press or the author do not want this book to do well. Odd. This is not a how-to-use-PowerPoint book, nor does it prescribe a method (which are two of its attractive features to me). But this is a very good book and it deserves some buzz. This would be an excellent supplementary textbook for a college-level speech-communications class, and of course, anyone who presents often will find the book provocative and practical. You may not agree with all the examples, but that's fine. The important thing is to get the conversation going.

If you can't afford yet another book related to PowerPoint/presentations, then you can get some feel for the material here in this article by the author.