I just came across a Scientific American article from 2009. Written by Henry L. Roediger and Bridgid Finn, "Getting It Wrong: Surprising Tips on How to Learn" has important implications for your webinar presentation content and style.
The authors point to studies done in an educational context where researchers compared tests in two scenarios. In the first, students were given the target material and told to study it through basic concentration and memorization. In the second, students were asked the questions before any information had been given to them, so they were bound to get the answers wrong. Then they were shown the correct answers, with much less time to study and memorize the information. The goal was to make the total amount of concentration time similar in both studies.
Students tested better on the targeted information when they first had a chance to guess and get the answer wrong. It turns out that this does not "muddle our brains with the wrong facts" or get our memories mixed up between what was the false information and what was the subsequently presented correct information. We do better when our brains are first switched into "active mode" - focused on the problem and thinking about how to solve it. Then when we get the right information, we are able to slot it into place in its proper application and remember it better.
What does this mean to you as a webinar presenter? When you want your audience to remember a salient point, don't just tell it to them. First challenge them. "What do you think the answer is?" or "How would you approach this?" or "How would you guess our product addresses this scenario?" Encourage your audience to switch from passively receiving information to actively joining in the information discovery process. Let them be wrong… non-judgmentally and without penalty. Then give them the correct answer. They will retain your information better (and you get the benefit of being seen as a more engaging, interactive speaker).
A tip o' the hat here to David Anderson at Articulate (@elearning on Twitter) for calling attention to the original article. His Twitter feed has a lot of good references for online instruction that are often useful in the broader presentation context.