Giving a speech? Conquer the five-minute attention span

If you dread seeing audience members checking their phones — or, worse, napping — while you’re talking, consider putting these tips to work.

FORTUNE — Maybe it’s the speed-of-light pace of technology, or the stress of having too much to do and not enough time to do it, or both, but when British bank Lloyds TSB set out to study what causes careless (and costly) household accidents, the researchers made an interesting discovery: The average adult attention span has plummeted from 12 minutes a decade ago to just 5 minutes now. That may be especially true at this time of year, when most of us would rather be at the beach.

So there you are, planning a presentation that could have a big impact on your career, for better or worse, and it’s half an hour long. “With an attention span of five minutes, the average audience is going to tune out 84% of your 30-minute speech,” says Sean O’Brien — unless, that is, you find ways to keep them interested.

An executive vice president at Atlanta-based online meeting and collaboration firm PGi, O’Brien offers these suggestions for doing just that. They’re drawn from a new PGi e-book (free on the company’s website) called The Little Black Book of Presentation Ideas.

1. Are you sure you need PowerPoint? “People fall back on PowerPoint because it’s easy and familiar,” O’Brien notes. “The trouble is, it doesn’t stand out. The audience has seen the same format 1,000 times, so they turn into zombies.” Alternatives like Prezi, Easel.y, or SlideRocket “are designed to be easy to use, and they can make more of a visual impact.

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“But maybe you don’t need slides at all. Sometimes they’re just a crutch,” he adds. O’Brien likes to quote Steve Jobs, who said, “People who know what they’re talking about don’t need PowerPoint.” He also cites research showing that 41% of U.S. employees would rather do their taxes or go to the dentist than sit through a slideshow — and 62% have either fallen asleep or left the room to escape a boring batch of slides.

2. If you do use slides, less is more. Start with “a killer first slide or opening remark,” O’Brien says, “with eye-catching visuals and concise language.” Then, for a 30-minute presentation, plan on no more than five to 10 slides. “If you have a slide deck with 30 slides in it, your presentation is doomed,” O’Brien says. “You also need to have each slide make just one main point of 15 words or fewer.” Talk too much and you’ll lose ’em, so get to the point.

3. Make smart use of unusual fonts and colors. Varying your visuals with different fonts, beyond the mainstream Microsoft Office and Keynote typefaces, can help you hold people’s interest, and they’re readily available from sites like Dafont, 1001 Free Fonts, Fontsbytes, and Fonts.com. “Don’t forget to give your text room to breathe,” O’Brien adds. “It should be big enough to be read from the back of the room.”

Color counts too. O’Brien notes that product marketers and interior designers rely on color to evoke different responses — red denotes power and urgency, blue is calming, orange conveys energy and enthusiasm, and so on — and you can do the same: “Give the colors in your presentation some thought. Often people get so focused on the factual content that they forget to consider the visual impact.”

4. It’s not all about the work. “The best presentations draw people in and make an emotional connection between the speaker and the audience,” says O’Brien. “You’ll be much more engaging and memorable if you tell a funny story or share a favorite quote, talk a bit about yourself and reveal a little of who you are outside the office.”

You don’t want to overdo this, of course, but handled right, it can be riveting. For proof, check out Sheryl Sandberg’s famous 2010 TED talk (the one that led to her writing Lean In). Sandberg’s frankness and self-deprecating humor carries it — and without a PowerPoint slide in sight.

5. Break through the “fourth wall.” Ever take a course in college where you never knew when the instructor was going to call on you, out of the blue, and expect some intelligent comment? It’s a time-honored technique for keeping an audience on its toes, since no one wants to be caught napping (literally or metaphorically), and it works for speeches, too.

“Involve your listeners by encouraging constructive interruptions, like questions,” O’Brien suggests. “Or pick people in the audience at random, and ask them to weigh in.”

Some expert speakers, like former GE (GE) chief Jack Welch, have made use of Twitter to let audience members Tweet a constant stream of questions and comments, which Welch then addresses in real time. It’s not a technique for the faint of heart, but it does keep people’s attention from wandering. These days, that’s no small feat. –Anne Fisher, contributor, http://management.fortune.cnn.com/2013/07/10/public-speaking-attention-span/