Final answer:
Expertise and trustworthiness influence the credibility of a source in persuasive communication. Credible sources with expertise and trustworthiness are more effective in persuasion. The use of the CRAAP test and ethos are methods to evaluate and establish credibility.
Step-by-step explanation:
Expertise and trustworthiness are two factors that affect the credibility of a source of a persuasive communication. In the field of persuasion, credibility is crucial as it determines how convincing the message will be to the audience.
Various studies have shown that speakers who are credible and possess expertise on the topic, as well as being deemed trustworthy, are more influential in their communication than those who are less credible.
For instance, the classic study by Howland & Weiss (1951) emphasizes the influence of source credibility on the effectiveness of communication.
The CRAAP test is used to assess the credibility, relevance, authority, accuracy, and purpose of a source, further highlighting the importance of credibility in evaluating information. Ethos, or ethical appeal, is another aspect that demonstrates the trustworthiness and credibility of a writer or authority.