It is likely they will rely on the belief that the longer the message, a. the more valid it must be.
Explanation:
Lucio was working for an ad agency. He accepted to prepare a brief radio ad for a politician. The ad is prepared for very small budget.
He knows that the ad will be played earlier in the morning or late at the night. If it is played in the morning, people will be engaged in their work. If it is played at the night time, all of them will be tired and will be getting ready for bed.
Lucio concluded that people will not be listening to the message with full attention. So they will believe that if the message is longer it will be more valid.