The brain is easily bored. This one fact explains why Apple does what it does in its product launches. A presentation based on the fundamentals of neuroscience includes frequent changes to keep people interested. But how frequent is “frequent” change?

The answer: 10 minutes.

Neuroscientists say our brains have a built-in stopwatch that ends around 10 minutes. In my conversations with University of Washington Medical School molecular biologist John Medina, he cites peer-reviewed studies that show people tune out of a presentation in the first 10 minutes. “The brain seems to be making choices according to some stubborn timing pattern, undoubtedly influenced by both culture and gene,” he says. “This fact suggests a teaching and business imperative: Find a way to arouse and then hold somebody’s attention for a specific period of time.”

Medina and other neuroscientists say speakers can re-engage an audience every 10 minutes if they introduce a change. A change can include a video, a story, a demonstration, etc.

In the Apple Event on September 12, the company introduced its newest Apple Watch (version four) and next generation iPhones. As they do in every major product presentation, Apple executives re-engaged the audience every 10 minutes. They do it by introducing change in the form of new voices.

Apple shares the stage every 10 minutes or less.

In the first 60 minutes of Apple’s September 12 event, the audience heard from 10 speakers (including chief designer Jony Ive, whose voice could be heard on a video describing the new Apple Watch). And no one spoke for more than 10 minutes. Here’s an example of how it works.

  • Apple CEO Tim Cook takes the stage and spends five minutes bringing the audience up to date on sales and products and introduces the two themes of the day: the Apple Watch and new iPhones.
  • After five minutes, Cook introduces Apple COO Jeff Williams to talk about the new Apple Watch.
  • Two minutes later, Williams plays a video that shows off the design of the new watch. The video resets the audience’s internal stopwatch.
  • Williams takes to the stage again and speaks for the longest uninterrupted time of any speaker (12 minutes). Williams, though, paused frequently as he was interrupted by applause 12 times. His segment was probably scripted for 10 minutes or less.
  • Williams introduces another speaker, Ivor Benjamin, president of the American Heart Association. Benjamin speaks for two minutes about the new health feature on the Apple Watch–an EEG to measure heart rate.
  • Williams presents for four minutes and plays another video. This time we hear the voice of chief designer, Jony Ive.
  • The video ends two minutes later. Williams concludes his portion of the presentation and hands it back to Tim Cook.

In the first 30 minutes, the audience watched three videos and heard four distinct voices.

The remaining 90 minutes followed a similar template, with no speaker taking more than 10 minutes on stage.

Marketing chief Phil Schiller took over the iPhone portion of the presentation. He spoke for exactly 10 minutes before introducing an iPhone product marketing director, Kaianne Drance, to demonstrate how enhanced graphics will improve gaming and app development. She, in turn, shared the stage with three app developers who also brought along gamers and guests. In a 15-minute segment, the audience saw nine people share the stage.

Remember, the brain gets bored easily. Keep your listeners engaged by introducing a cast of characters. If you’re pitching investors, bring along members of your team or a customer. If you’re delivering a solo presentation, insert videos to reset your audience’s internal stopwatch.

Above all, stick to the 10-minute rule to keep your audience’s attention. Don’t give your listeners a chance to get bored.