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Testimony consists of information provided by other people. Typically, you will find testimony from the sources you research at the library and online, or through interviews.

Expert testimony consists of statements made by credible sources who have professional or other in-depth knowledge of a topic. As with any source, you must carefully assess any expert testimony and be sure that expert sources have specialized knowledge of the topic, objectivity, and observational capacity. Testimony from expert sources is likely to increase audience members’ acceptance of your claims. Thus, you should try to use expert testimony when you are asserting claims the audience may not accept.

A second type of testimony is lay testimony, which consists of statements made by persons with no special expertise in the subject they are discussing. Because they lack expertise, lay sources should generally not be used to prove factual claims in a speech. This type of testimony is not a substitute for evidence. For example, testimony from laypersons would not credibly prove that a low-carbohydrate diet improves people’s health or predict the effect of expanded offshore oil drilling on the U.S. economy. However, lay testimony can help you show how a typical person has been affected by your topic. Thus, you could quote lay sources to explain their particular experiences with a low-carbohydrate diet or to discuss how they were affected by high gas prices.