“Here you have the advertiser’s ideal—the family group in its moments of relaxation awaiting your message,” said CBS. "Nothing equal to this has ever been dreamed of by the advertising man." It is, as we shall see, one thing to sell access to the minds, quite another to predict reliably the audience’s frame of mind; and by dictating the moment of infiltration, radio claimed to do just that. At the time and place of CBS’s choosing, the audience would be "at leisure and their minds receptive."

Tim Wu, The Attention Merchants, loc. 344