Historian: Radio drama requires its listeners to think about what they hear, picturing for themselves such dramatic elements as characters' physical appearances and spatial relationships.
Evidence
Radio drama requires its listeners to think about what they hear, picturing for themselves such dramatic elements as characters physical appearances and spatial relationships.
Earlier generations, for whom radio drama was the dominant form of popular entertainment, regularly exercised their imaginations.
Conclusion
Today's generation of television viewers do so [regularly exercise their imaginations] less frequently.
Evaluate
The argument's conclusion is too strong. Without knowing everything else that has changed for today's generation, it's not possible to say how much more or less today's generation exercises their imaginations While it may be true that television provides less opportunity to exercise one's imagination, it could also be true that other activities more than compensate for any loss that resulted from the switch from radio to television.