Television and radio once again showed results high above 
lecture and print. Unexpectedly to the testers, however, radio 
now stood significantly above television. It was a long time 
before the obvious reason declared itself, namely that TV is a 
cool, participant medium. When hotted up by dramatization 
and stingers, it performs less well because there is less 
opportunity for participation. Radio is a hot medium. When 
given additional intensity, it performs better. It doesn’t invite 
the same degree of participation in its users. Radio will serve as 
background sound or as noise-level control, as when the 
ingenious teenager employs it as a means of privacy. TV will 
not work as background. It engages you. You have to be with  
it. (The phrase has gained acceptance since TV.)

     A great many things will not work since the arrival of TV. 
Not only the movies, but the national magazines as well, have