"How else do you suppose the participants will know about the main event?"

In many cases the participants do not know each other outside the virtual community.

Even though the participants know exactly what they are getting into, the experience is unsettling.

Since the settlement is sealed, only the participants know whether any money changed hands.

The participants did not know what they were taking.

This means they hold specific information on the tests before the participants should know.

The participants did not know each other before the adventure, except on season four.

How much do participants know going into a space tour?

Apparently the other participants knew this was coming, because they had prepared statements.

Neither the researchers nor the participants know which the real medicine is.