"In interactivity, people expect to control the query and get back the answer," Mr. Sagan said, adding his own customized parable: "I have an odd Swiss watch that requires an authorized dealer to change the battery.
In the United States, early experiments in interactivity were ambitious but disappointing.
Perhaps the ultimate in interactivity, though, is a continuing series of "guitar nights" the museum has set up.
He is an audience of one, and his privileged screening is a powerful exercise in interactivity: when he is done, he has the power to reverse a ruling based on the replays he just saw.
With its daft host, throwaway one-liners and emphasis on family competition, it appropriates the ingredients of traditional weekend entertainment, but adds in interactivity and a bit of vitality.
The Well has never made much money, but its early experiment in interactivity laid the groundwork for a lot of other commercial enterprises that also looked a lot like Tom Sawyer's getting his pals to whitewash the fence for him.
