If you want to know what your attendees or potential attendees are thinking, the best thing to do is to ask them. Surveys and audience-response systems are tried-and-true ways to unearth opinions, but here’s another: Synthetron, a remarkable tool for large-group virtual brainstorming.

Here’s how Synthetron works. Attendees log onto a Web site for a one-hour discussion and are presented with a screen like the one below.

On the left side of the interface, organizers present a question, and attendees have the option to type in a response anonymously. Participants must react to responses on their screen by using their mouse to place a blue arrow along a continuum on the right, indicating how much they “oppose” or “agree” with a comment. (Attendees don’t have to comment themselves but must score all the comments that come in.) In order to handle large groups (up to 1,000), participants are randomly grouped. Comments that get significant support (a high percentage of “strongly agree”) are then presented to more groups to get their reactions. The comments that survive what the company calls a “Darwinian selection of ideas” are labeled “synthetrons.” An oganization can examine the synthetrons at the end of the brainstorming session to see what ideas get broad support.

The Belgium-based company says some clients, such as Ikea and the Belgian Direct Marketing Association, use the system to engage attendees before a meeting in order to test ideas or fine-tune an agenda. Recently 109 participants from the European meetings and events industry used the system to weigh in on the viability of the 7Cs Manifesto, a document on the future of the industry that came out of the European Event Summit in Luxembourg last year. Other companies have used the system as part of a hybrid meeting experience.