What impact do stories have when they are told directly from those individuals who were there, like World War II veterans at Pearl Harbor John Seelie (L) and Armando "Chick" Gallela featured in the photo above?

These stories have greater credibility.

Explanation:

When real stories are told by individuals who witnessed the story happen, we tend to give more credibility to the events told. This is because the people who experienced the events know how to tell in detail what really happened, in addition to transforming the story into a more personal and intimate account, as they manage to convey the emotion and true feelings of those who experienced this moment. This makes the story more realistic and credible.