Personal response systems (PRS) are known under several names. "Clickers"; "Audience Response Systems"; "Group Response Systems"; and "Classroom Performance Systems"; all of these are systems where the audience can respond to questions or give feedback to the presenter of a lecture or workshop whilst that presentation is taking place. This allows for immediate, and (if wished) anonymous feedback to the presenter and to the class.
Murphy, B. & Smark, C. J. (2005). Personal Response Systems Workshop. In J. Kent (Eds.), Proceedings of the Accounting Educators Forum 2005 (pp. 137-154). Australia: Charles Stuart University.