Interior thought' is a convention which is special to the radio medium. In radio the listener can be instantly transported inside the head of a character and can hear those secret, private thoughts that are often better left unsaid. Radio drama has been described as 'The Theatre of the Mind'. The potential conflict between exterior dialogue and speech and interior thought creates a special ground of conflict which is a fertile area for the creative radio playwright. The key to writing successful plays for radio is to realise that the listener can only understand what is going on by what he or she hears.
Radio drama has only one chance to be successful.
A dissatisfied listener only has to twiddle the radio dial, or turn the switch off altogether and the playwright has lost the audience. It's important to bear in mind that a radio playwright can't afford to bore or confuse the listener. All good writing requires a strong element of honesty and integrity from the writer. The great dramatists strive to express a truth about human experience or human nature. This means that superficiality, pretentiousness and ostentation are quickly recognised by the listener and will normally lead to failure when the listener switches off.