There is nothing more annoying, having spent hours on preparing a perfect presentation, than to be thrown off course or put off your stride by someone in the audience 'hijacking' the presentation, especially when you're trying to keep to a strict time slot. You've prepared six slides and they take you off on so many tangents you never get past slide one before your allotted time is up. Some people almost seem to enjoy interrupting presentations and treat it as a demonstration of their power.
If you're presenting to a customer or audience composed of more senior people than yourself, it's impossible to stop this completely. But there are certain things you can do to minimize them in the first place or handle them when they occur.
1. Explain the 'big picture' first
When presenting to a senior audience, bear in mind that they are often 'big picture' people (their ability to see the wood rather than the trees is often one of the main reasons they're in a senior position).
Left-brained people are very logical and thorough and detailed and like to build up to the whole, step-by-step, like building a wall brick-by-brick. But right-brained people's brains don't work this way. They can't concentrate on the individual bricks until they know what type of building is being built. Without this the individual bricks in themselves are meaningless. They need to see the whole first for the details to make sense to them.
I recently started to watch a movie I'd never heard of on TV (I'm right-brained, by the way), although it starred some quite well-known actors. But because I had no idea what it was about, I switched off after about ten minutes. I couldn't concentrate on the individual scenes because I had no 'big picture' (no pun intended) to put them into context.
Always give them an overview of what you're going to cover before you do it. I'm not talking about a detailed agenda which takes two full minutes to go through (that in itself virtually invites interruptions, especially when there are time pressures), but a brief overview.
So after a great impactful opening (see How To Grab 'Em By The Throat), you might say, "Today I'm going to talk about problem X/Y/Z, and I'm going to concentrate on five areas: 1) why it's such a problem and what it's costing us; 2) the different options we've examined; 3) the solution we'd like approval for today; 4) the costs and financial benefits; and 5) the implications to A/B/C."
Now doing this doesn't completely eradicate the danger of interruptions, but it does make them less likely. Because if someone knows something is going to be covered within the presentation, she's less likely to ask a question about it during your first slide.
2. Simplify and build your slides
Most presenters' slides are far too detailed and complex and need simplifying (see How To Avoid The 'Data-Dump': Keeping Your Slides Simple). This just serves to distract the audience and invite comments and questions you don't want. Constantly ask yourself: 'Does this help me make my point?' If it doesn't, take it off the slide. Every single bullet point, graph, chart and number should have to justify its presence, so that only information that helps make your point is left.
This problem is then compounded when all the information/words/data/bullets are shown onscreen at once. There is a reason PowerPoint has a 'build' function; use it!
You can't say, "I want you to ignore bullet points 2-7 and just concentrate on number 1." If there's a lot of information onscreen, it is human nature to read it.
Plus ..... the audience will read the slides far faster than you can explain it. So if you're interrupted by a question about bullet point 5 when you're still talking about bullet point 1, you only have yourself to blame.
Building the slides helps you keep control of what the audience is thinking (and asking questions) about.
3. Set The Scene
If you've left a period of time at the end for questions, don't be afraid to say so. Let the audience know right at the start that you'd like questions at the end, but give them a reason why that's in their interest. Obviously you can't say, "I've left 5 minutes at the end for questions; hopefully that will minimize your inane interruptions."
Instead, after you've given your brief overview of the presentation, add, "And finally I've left some time at the end to answer any questions. I imagine you've got a lot of things to cover on the agenda today, and if we take questions as we go along there's always a danger of getting side-tracked and going off on a tangent and we'll end up taking half an hour instead of the 15 minutes you've given me. I'm pretty sure I'm going to cover off all the obvious things you'll want to know, but if I haven't and you have questions, if you can keep them to the end, I'd appreciate it."
If you haven't done this you can't complain if the audience interrupts. After all, they haven't been told not to.
4. Stand Your Ground
Finally, stand your ground. If you've set the scene as suggested above and nobody has objected, you're perfectly within your rights to refuse to be interrupted. Simply say, "That's a good question Mike. I'm not dodging it, but I think I cover it a little later on. But if I don't, remind me at the end and I'll cover it then. Is that OK?"
Now it can take guts to do this if the questioner/interrupter is a lot more senior to you, but try it. You might be surprised. He might just nod and accept it. Or ...... another member of the audience might come to your rescue and suggest it's left to the end.
And if he doesn't accept it and insists on an answer there and then? Accept defeat gracefully and answer it. But you have nothing to lose by trying it.