The 70% Rule: When Imperfect Understanding Is Best

At conferences, maybe it’s a good thing if some engineers don’t understand your entire presentation

2 min read
Illustration by Dan Page
Illustration: Dan Page

I recently attended a conference by watching live presentations over the Internet. This was a kind of out-of-body experience, as I virtually hovered over the meeting without the visceral interaction of physical attendance. My attention often wavered, and I viewed the entirety through a sometimes unfocused perspective.

After two days of this, I arrived at an unexpected observation. The talks fell into two distinct categories—those that I understood almost entirely, and those that I hardly understood at all. There were very few in the middle. This got me thinking about the quality and understandability of conference presentations, and how this has changed through the years.

I’ve attended probably hundreds of conferences. A long time ago the programs were filled with “talks,” which were sometimes called “papers.” Gradually, “talks” morphed into “presentations.” In some settings, the presentations were called “briefings,” while at more august events they became “speeches.” There are discernible nuances among these descriptions, but in all of them the ultimate aim was ostensibly to inform or educate the audience.

Recalling how conferences were many years ago, I believe that engineers have now greatly improved their ability to inform their listeners. There have been two significant evolutionary forces. PowerPoint caused “talks” to become “presentations,” and more recently the advent and general availability of TED talks has set goals for the quality of presentations.

But in thinking about the understandability, I pondered a strange question. As a speaker, what percent of the audience do you really want to understand your talk?

Clearly, the answer is not zero, though sometimes there is an urge to impress the audience with your knowledge and accomplishment. I remember attending a board meeting many years ago of a very large and important government defense program. One speaker talked about a technology that might be applied in the program. The talk was way over my head, and I gave up and tuned out. At the end, the speaker asked if there were any questions. Only one hand went up, and the room went expectantly silent, as that hand belonged to one of the most famous physicists in the world. In his characteristic accented whisper, he said, “I have understood...nothing...of this.” We all realized immediately that this was not a confession but an accusation. Not something you’d want to happen after your own talk!

On the other hand, you might think that the right answer to my question is that all of the audience should understand your talk. But maybe not. I think that I often get more out of talks that I don’t understand than from those that I do. I may not learn much that’s new from those that I understand, whereas some of those that I don’t understand leave me feeling that this was an important subject that I need to know more about. In today’s world you can learn about anything on the Internet, but time is limited, and the question is what is worth exploring. Just getting a taste of a topic you don’t understand can be quite valuable.

If everyone in the audience understands your talk, there is a good chance that a fair fraction of the audience will not learn anything new from it, so maybe you shouldn’t want 100 percent of the audience to understand your talk.

The right answer to my question is that 70 percent of the audience should understand your talk. But I just made that up. I have no idea what the answer should be.

This article appears in the July 2018 print issue as “When Imperfect Understanding Is Good.”

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