To be an effective public speaker, one should be able to utilize devices that will capture the attention of the audience. Getting them on stage is considered an effective way to capture the interest of the audience. Make them participate. The rest of the audience will almost always stay attentive when one of them gets on stage. Why? Because they will be curious to see what you will be doing to one of them. There’s also the fact that they’re thinking it could be them up there and this will save their egos from embarrassment and they would at least know what’s going on.
Nothing beats the excitement of getting someone to be on stage who really should not be there in the first place no matter how excellent or good you are as a public speaker or as a presenter. If you call someone unexpectedly, everyone else is going to wonder if they are going to be next. As you go through your presentation, the audience will most likely think about the point you are making, and as you take your point across, the audience will understand. You have forced them to listen as well as respond to your statement in the privacy of their minds because you have made them pay attention.
But there are others who are very sensitive and extremely shy and if they hear that you will be calling on them up on the stage, then they might try to withdraw going through the rest of your presentation. Here, the objective is to gain an audience and avoid losing any of them.
Make it clear prior to your asking someone to come up on stage with you that you are asking for a volunteer and that no one will be forced if they do not want to. Notice that if the majority of your audience are shy, once you finally get someone to be on stage, all of them will almost always heave a sigh of relief.
Giving your audience due recognition is yet another way to get the audience to participate as well as pay attention. Try to acknowledge a single member of the audience for a specific achievement or a moment of a good performance, or also acknowledge a group of the audience.