Want to move part of your audience to a higher level of commitment? . . . maybe to locate the real buyers in the group .. . or maybe to locate the leaders of the group.
Put reserved signs on several rows of chairs right up front so nobody sits in them. As you go through your presentation you can put out a challenge to the group, or simply ask a question like, "Who would like to take this to the next level?"
When people raise their hands you can say something like, "If you are really serious, pick up your materials and come down and sit in these front rows.
"You would do this maybe 1/4 to 1/2 of the way into your presentation, or at least after you have shown them some value in your material. Then you would have 3/4 or 1/2 of your presentation left to really connect with them. (People sitting closer will have a much greater connection with you.)
Another thing I better warn you of . . . you better be pretty darn good on stage and confident of yourself because you will look pretty bad if no one jumps up to move to the front. Also, you should be very cognizant of the type of group you try this on because it probably won't work well on really conservative groups.
Once the chairs fill up you could give out some kind of bonus which rewards them for being bold and decisive. Later on in the speech they will be more likely to be bold and decisive in doing whatever you ask them, because you have shown them rewards for doing so.
This technique is very good for identifying people that are likely to buy your back of the room products or your coaching /consulting programs.