Consequently, whether to use pronouns or not depends on how we want to assign credit or blame, and how subjective or objective we want what is being said to seem.

As O’Barr had predicted, slight differences in wording changed how the witness was perceived. Speaking like a professional made the witness seem more credible. Listeners saw them as more trustworthy, competent, and convincing, and were more likely to believe what they had to say.

We started with books. Analyzing around a quarter of a million Amazon book reviews revealed that present tense increased impact. Saying a book “is” rather than “was” a good read or “has” rather than “had” great plot development led other people to find a review more helpful.

Even in music, though, we found the same result. Music reviews that used more present-tense verbs were more persuasive.

But in this context, it turned out that the exact opposite occurred. Expressing doubt about a contentious issue actually increased persuasion. Particularly among people who already had strong beliefs, hearing someone else wasn’t sure about their opinion encouraged them to change their mind in that direction.