In a recent study by Shana Carpenter and Alexander Toftness, reported by The Science of Us, they found that when people were asked a question about the topic of a video before they watched the video, they remembered significantly more about the video than people who weren’t asked a question.
Interestingly, this memory-enhancing effect applied not only to the information that answered the question—it applied to all of the information presented in the video.* This gives further support to the idea of using a question as a hook for your speech, or perhaps even structuring your entire speech around a series of questions, as Matt Abrahams proposes in Speaking Up without Freaking Out.
One thing to note about about this research is that it involved participants actually answering the pre-questions (i.e., they were real questions, not rhetorical questions). Whether rhetorical questions would have the same effect remains to be seen.
* This is in contrast to what happens in writing. Prior research has found that when written text is preceded by a question, the question enhances memory of information that answers the question, but impairs memory of information that doesn’t answer the question. This is because the reader selectively searches (i.e., skims) the text for the answer, something that’s harder to do with a video or a speech.